Heat and Corrosion Resistant Castings: Their Engineering Properties and Applications

HEAT AND CORROSION RESISTANT CASTINGS: THEIR ENGINEERING PROPERTIES AND APPLICATIONS

Publication No 266

Distributed by the Nickel Development Institute, NiDl courtesy of Inco Limited Contents Pages Part I. Heat-Resistant Alloy Castings ...... 4-26 Introduction ...... 4 Typical Casting Compositions of Heat-Resistant Alloy Castings, Table I ...... 4

Effect of Constituents ...... 5

Groups of Heat-Resistant Alloy Castings ...... 6-8 Chromium-Iron Alloys (HA, HC, HD) Chromium-Nickel-Iron Alloys (HE, HF, HH, HI, HK, IN-519, HL) Nickel-Chromium-Iron Alloys (HN, HP, HT, HU, HW, HX) Chromium-Nickel Alloys (50Cr-50Ni, IN-657)

Selecting the Proper Alloy ...... 8

Heat-Resistant Alloy Casting Design ...... 9

High-Temperature Mechanical Properties ...... 9-15

High-Temperature Corrosion Resistance ...... 14,16

Room Temperature Properties ...... 16

Industrial Applications of Heat-Resistant Alloy Castings Aeronautical ...... 17 Cement ...... 17 Glass & Enameling ...... 17-18 Heat Treating ...... 18-21 Petroleum, Petrochemical Refining &Chemical ...... 22-24 Power Plants ...... 25 Steel Mill Equipment ...... 26 Smelting & Refining Equipment ...... 26

2 Part II. Corrosion-Resistant Alloy Castings ...... 27-47 Introduction ...... 27 Typical Casting Compositions of Corrosion-Resistant Alloy Castings, Table V .... 27

Room Temperature Properties ...... 28

Effect of Constituents ...... 29-30

Corrosive Attack ...... 30-31

Groups of Corrosion-Resistant Alloy Castings ...... 31-33 Martensitic Alloys (CA-15, CA-40, CA-6NM, CA-6N) Ferritic and Duplex Alloys (CB-30, CC-50, CD-4MCu) Austenitic Alloys (CE-30, CF types, CG-8M, CH-20, CK-20, CN-7M, CN-7MS, IN-862) Precipitation Hardenable Alloys (CB-7Cu-1, CB-7Cu-2) Nickel-Base Alloys (CZ-100, M-35, CY-40, Alloy 625, CW-12M, N-12M, Ni-Si)

Corrosion Data ...... 34-37

Industrial Applications of Corrosion-Resistant Alloy Castings ...... 38-48 Aeronautical ...... 38 Architectural ...... 38 Chemical & Petroleum ...... 39-40 Process Industries Equipment ...... 41-44 Hydraulics ...... 45 Marine ...... 44 Power–Nuclear & Conventional ...... 45-48

Part Ill. Fabrication Data for Heat & Corrosion-Resistant Alloy Castings .... 49-52 Machining ...... 49-51 Welding ...... 51-52

3 Part I Heat-Resistant Alloy Castings

The heat-resistant casting alloys are those composi- rial Specifications (AMS) of the Society of Automotive tions that contain at least 12% chromium which are Engineers, United States Government Military Specifi- capable of performing satisfactorily when used at tem- cations (MIL), the Society of Automotive Engineers peratures above 1200 ºF. As a group, heat-resistant Specifications and the Unified Numbering System compositions are higher in alloy content than the (UNS) developed by the Society of Automotive Engi- corrosion-resistant types. The heat-resistant alloys are neers and the American Society for Testing and Mate- composed principally of nickel, chromium and iron to- rials. Standard ACI designations are listed in Table I. gether with small percentages of other elements. Nickel The Alloy Casting Institute designations use "H" to and chromium contribute to the superior heat resistance indicate alloys generally used in applications where the of these materials. Castings made of these alloys must metal temperature exceeds 1200 ºF. The second letter meet two basic requirements: indicates the nominal nickel content, increasing from A 1. Good surface film stability (oxidation and corro- to X. sion resistance) in various atmospheres and at the The chemical compositions of the heat-resistant cast- temperature to which they are subjected. ing alloys are not the same as those of the wrought 2.Sufficient mechanical strength and ductility to meet alloys. Therefore, Table I lists only the nearest wrought high temperature service conditions. alloy AISI type number. Alloy Casting Institute designa- The heat-resistant alloys are listed in Table I along with tions or their equivalents should always be used when their chemical compositions and designations. identifying castings. Commercial cast heat-resistant alloys can be identified The SAE specification designations use the nearest by designations of the Alloy Casting Institute, now a wrought composition (AISI type number) and prefix it division of the Steel Founders' Society of America, and with the number 70 ºFor heat-resistant castings: for ex- the American Society for Testing and Materials.* Some ample, 70310 is equivalent to HK. In the Unified Num- of these materials are also listed in the Aerospace Mate- bering System, the Jxxxx number series is assigned to *See ASTM Specification A 297 cast steels.

TABLE I Compositions of Heat-Resistant Alloy Castings

Alloy CHEMICAL COMPOSITION, % Nearest Casting Alloy ASTM UNS AISI Institute Type Specification No. Ni Cr C Other Type Mn Si Mo Designation max max max HA 8-10Cr A217 – – – 8-10 0.20 max 0.35-0.65 1.00 0.90-1.20 Fe bal HC 28Cr A297 446 J92605 4 max 26-30 0.50 max 1.00 2.00 0.5 Fe bal HD 28Cr-6Ni A297 327 J93005 4-7 26-30 0.50 max 1.50 2.00 0.5 Fe bal HE 28Cr-9Ni A297 312 J93403 8-11 26-30 0.20-0.50 2.00 2.00 0.5 Fe bal HF 19Cr-9Ni A297 302B J92603 9-12 19-23 0.20-0.40 2.00 2.00 0.5 Fe bal HH 25Cr-12Ni A297, A447 309 J93503 11-14 24-28 0.20-0.50 2.00 2.00 0.5 Fe bal HI 28Cr-15Ni A297 – J94003 14-18 26-30 0.20-0.50 2.00 2.00 0.5 Fe bal HK 25Cr-20Ni A297, A351 310 J94224 18-22 24-28 0.20-0.60 2.00 2.00 0.5 Fe bal A567 IN-5191 24Cr-24Ni – – – 23-25 23-25 0.25-0.35 1.00 1.00 – Cb 1.4-1.8; Fe bal HL 30Cr-20Ni A297 – J94604 18-22 28-32 0.20-0.60 2.00 2.00 0.5 Fe bal HN 25Ni-20Cr A297 – J94213 23-27 19-23 0.20-0.50 2.00 2.00 0.5 Fe bal HP 35Ni-26Cr A297 – J95705 33-37 24-28 0.35-0.75 2.00 2.00 0.5 Fe bal HP-50WZ 35Ni-26Cr – – – 33-37 24-28 0.45-0.55 2.00 2.50 – W 4-6; Zr 0.1-1.0; Fe bal HT 35Ni-17Cr A297, A351 330 J94605 33-37 15-19 0.35-0.75 2.00 2.50 0.5 Fe bal HU 39Ni-18Cr A297 – J95405 37-41 17-21 0.35-0.75 2.00 2.50 0.5 Fe bal HW 60Ni-12Cr A297 – – 58-62 10-14 0.35-0.75 2.00 2.50 0.5 Fe bal HX 66Ni-17Cr A297 – – 64-68 15-19 0.35-0.75 2.00 2.50 0.5 Fe bal Chromium Nickel 50Cr-5ONi A560 – – bal 48-52 0.10 max 0.30 1.00 – Fe 1.0 max IN-6571 50Cr-48Ni – – – bal 48-52 0.10 max 0.30 0.50 – Cb 1.4-1.7; N 0.16 max; Fe 1.0 max 1INCO Designation

4 EFFECT OF CONSTITUENTS

Nickel Nickel is present in cast heat-resistant alloys in others in the United States, Japan and Britain. Alteration amounts up to 70%. Its principal function is to strengthen of the carbide morphology from lamellar to discrete and toughen the matrix. Microstructurally, nickel particles seems to be the important factor; HP-50WZ promotes the formation of austenite which is stronger (Table I) and IN-657 (Tables I through IV) are examples and more stable at elevated temperatures than ferrite. of commercial alloys with improved property levels. Nickel contributes to resistance to oxidation, car- burization, nitriding and thermal fatigue. INFLUENCE OF MICROSTRUCTURE Chromium The iron-chromium-nickel heat-resistant alloys de- The chromium content in heat-resistant alloys varies signed for service up to 1200 ºF often have mixed from approximately 10 to 30%. Chromium imparts resis- ferriteaustenite matrices. However, alloys intended for tance to oxidation (scaling) at elevated temperatures, service above 1200 ºF are austenitic. The compositions and to sulfur-containing atmospheres. Also, chromium of these alloys are generally adjusted to prevent the for- carbides precipitate in the matrix and contribute to high- mation of ferrite which has a detrimental effect on high- temperature creep and rupture strength. In some alloys, temperature creep-rupture strength. Long-time expo- chromium increases resistance to carburization. It also sure at high temperatures, e.g., 1500 ºF, can result in improves the resistance of the alloys to the action of transformation of ferrite to the sigma phase with signifi- many other corrosive agents at normal and elevated cant loss of toughness at room temperature. Thus, in temperatures. It promotes the formation of ferrite in the these alloys, the high-temperature strength is based microstructure. primarily on the solid solution strengthening of the aus- tenite by the addition of nickel, chromium and certain Other Elements minor elements. Carbides also contribute to strengthening these al- Nickel and chromium have the greatest effect on the loys. As noted previously, these alloys have carbon properties of heat-resistant castings but the minor alloy- contents ranging from 0.20 to 0.75%. In the as-cast ing elements also influence the properties. condition, the microstructures consist of carbides dis- Carbon content ranges from 0.20 to 0.75%. It pro- persed in an austenite matrix which also contains dis- motes dispersion-strengthening through the formation of solved carbon. By interfering with dislocation move- carbide in the structure. Increasing the carbon content ment, these precipitated carbides assist in strengthen- improves the high-temperature strength and creep ing the alloy. During long service at elevated tempera- resistance of the heat-resistant alloys at the expense of tures in the range 1000 to 1800 ºF, additional chromium lower ductility. carbides precipitate in finely divided form and also as- Silicon has a beneficial effect on the high- sist in strengthening the alloys. At temperatures some- temperature corrosion resistance and on resistance to what above 1800 ºF, the primary carbides have a ten- carburization. In amounts greater than 2%, it lowers the dency to coalesce and the secondary carbides to redis- high-temperature creep and rupture properties and, in solve in the matrix. Nickel and chromium retard this general, the silicon content is limited to 1.5% in castings tendency. intended for service above 1500 ºF. Silicon promotes the formation of ferrite. GROUPS OF HEAT-RESISTANT Manganese, although important in melting opera- tions, has little or no effect on the mechanical properties ALLOY CASTINGS or corrosion resistance when present in moderate The heat-resistant alloys can be classified according amounts. to composition and metallurgical structure into three Molybdenum improves the high-temperature creep broad groups: and rupture strength by promoting stabilization of car- 1. Chromium-iron alloys: HA, HC, HD. bides. In some instances, it also increases high- 2. Chromium-nickel-iron alloys: HE, HF, HH, HI, HK, temperature corrosion resistance. It slightly increases IN-519, HL. resistance to carburization. 3. Nickel-chromium-iron alloys: HN, HP, HT, HU, HW, Work to improve the creep and stress rupture proper- HX. ties of the heat resisting chromium-nickel-iron alloys In addition, chromium-nickel heat-resistant alloys in- through the addition of small amounts of tungsten, zirco- clude 50Cr-50Ni and IN-657. nium, titanium, columbium, nitrogen, or combinations of them, has been pursued for several years under Steel A general discussion of each group is followed by a Founders' Society of America sponsorship and by discussion of each alloy.

5 resistance and is frequently recommended for service in CHROMIUM-IRON ALLOYS sigh-sulfur atmospheres where alloys containing higher This group consists of alloys in which chromium pre- nickel cannot be used. Because of its high alloy content, dominates with up to 30% chromium and up to 7% nickel. it is suitable for use up to 2000 ºF. The alloy has moder- These alloys are ferritic and have relatively low hot ately high hot strength and excellent ductility. It is widely strength. They are seldom used in critical loadbearing used for parts such as conveyors in furnaces, recupera- parts at temperatures above 1400 ºF, but have found use tors, coke oven exhaust castings, roasting furnace cen- in applications involving uniform heating and certain ter shafts and tube support castings. Prolonged expo- atmospheric conditions, such as high-sulfur atmospheres. sure at temperatures around 1500 ºF may promote for- The alloys in this group include the HA, HC and HD types. mation of the sigma phase with consequent low ductility at room temperature.

HA (9Cr) Type HA is a chromium-molybdenum-iron alloy that is HF (19Cr-9Ni) resistant to oxidation up to about 1200 ºF. The molyb- This type is comparable to the popular wrought denum content contributes desirable strength properties corrosion-resisting 18-8 compositions and is suitable for to the alloy at these moderate temperatures. Typical use up to around 1600 ºF. It approaches the HH grade uses are furnace rollers, Lehr rolls, refiner fittings and in many properties and combines moderately high hot trunnions. strength and ductility. Its microstructure is essentially austenitic. Typical uses include burnishing and coating rolls, furnace dampers, annealing furnace parts, etc. HC (28Cr-4Ni max) The HC type is limited to applications where strength is not a consideration or for moderate load-bearing HH (25Cr-12Ni) service around 1200 ºF. It provides excellent resistance This type is one of the most popular of the heat- to oxidation and flue gases containing sulfur at tempera- resistant alloys and accounts for about one-fifth of all tures as high as 2000 ºF. It is also used where high nickel heat-resistant casting production. This alloy contains content tends to crack hydrocarbons through catalytic the minimum quantities of chromium and nickel to sup- action. Due to the low nickel content, the ductility and ply a useful combination of strength and corrosion resis- impact toughness are very low at room temperatures tance for elevated temperature service above 1600 ºF. and the creep strength is very low at elevated tempera- The chromium range is high enough to assure good tures. Typical uses are boiler baffles, furnace grate scaling resistance up to 2000 ºF in air or normal bars, kiln parts, recuperators, salt pots and tuyeres. products of combustion. Sufficient nickel is present, aided by carbon, nitrogen and manganese, to maintain austenite as the major phase; however, the HD (28Cr-6Ni) microstructure is sensitive to composition balance. For The HD type has the best hot strength, weldability high ductility at 1800 ºF, a two-phase structure of and high-temperature corrosion resistance of the austenite and ferrite is appropriate but such a structure chromium-iron group. HD can be used for load-bearing has lower creep strength If high creep strength is applications up to 1200 ºF, and where only light loads needed and lower ductility can be tolerated, a are involved up to 1900 ºF. It is suitable for use in high- composition balanced to be completely austenitic is sulfur atmospheres. Long exposures to temperatures in desirable. the range 1300 to 1500 ºF may in some cases result in considerable hardening, accompanied by a severe loss Alloy HH is covered by ASTM specification A 447 of room temperature ductility through the formation of which recognizes two types. Type I is partially ferritic the sigma phase. Typical applications are roaster fur- and Type II predominately austenitic. Type I has a max- nace rabble arms and blades, salt pots and cement kiln imum magnetic permeability of 1.70 and Type II of 1.05. ends. Because of its high creep strength and relatively low ductility, Type II is useful in parts subject to high constant CHROMIUM-NICKEL-IRON ALLOYS load conditions in the range from 1200 to 1800 ºF Some typical uses are for furnace shafts, beams, These alloys are characterized by good high- rails and rollers, tube supports and cement and lime kiln temperature strength, hot and cold ductility, and resis- ends. Type I alloy is used where hot ductility is more tance to oxidizing and reducing conditions. They are important than hot strength, and is preferred for welding. useful for atmospheres high in sulfur, particularly under reducing conditions. These alloys contain 8 to 22% Both types of HH alloy have good resistance to sur- nickel and 18 to 32% chromium, and may have either a face corrosion under the various conditions encoun- partial or a completely austenitic microstructure. They tered in industry, but are seldom used for carburizing include types HE to HL. applications because of embrittlement caused by ab- sorption of carbon. Experience has indicated that HH alloys can withstand repeated temperature changes or HE (28Cr-9Ni) differentials reasonably well; however, they are not gen- This type has excellent high-temperature corrosion erally recommended for severe cyclic service such a 6 HI (28Cr-15Ni) HN (25Cr-20Ni) This alloy is resistant to oxidation up to 2150 ºF. Its This alloy has properties somewhat similar to the composition is such that it is more likely to be completely more widely used HT alloy but has better ductility. It is austenitic than the lower alloys of this group, hence it used for highly stressed components in the has more uniform high-temperature properties. This 1800-2000 ºF range. It has also given satisfactory ser- type is used for billet skids, conveyor rollers, furnace vice in several specialized applications, notably brazing rails, lead pots, retorts for magnesium production, fixtures at temperatures up to 2100 ºF. Among its appli- hearth plates and tube spacers. cations are chain, furnace beams and parts, pier caps, brazing fixtures, radiant tubes, tube supports and torch nozzles. HK (25Cr-20Ni)

The HK alloy provides one of the most economical combinations of strength and surface stability at tem- HP (35Ni-26Cr) peratures up to and above 1900 ºF and accounts for This alloy is related to the HN and HT types but almost half of the heat-resistant alloy tonnage. contains more nickel than the HN alloy and more chro- It can be used in structural applications up to 2100 ºF mium than the HT alloy. This composition makes the HP but is not recommended where severe thermal shock is a alloy resistant to both oxidizing and carburizing atmo- factor. It is used for parts where high creep and rupture spheres at high temperatures and provides high stress- strengths are needed such as steam methane reformer rupture properties in the range 1800-2000 ºF. It is used tubing, ethylene pyrolysis tubing, gas turbines, furnace for ethlene pyrolysis tubing, steam methane reformer door arches and chain, brazing fixtures, cement kiln tubing, heat treating fixtures and radiant tubes. Several nose segments, rabble arms and blades, radiant tubes, proprietary modifications containing columbium and/or retorts and stack dampers. tungsten are also being used.

IN-519 (24Cr-24Ni-1.5Cb) HT (35Ni-17Cr) This alloy is a modification of HK alloy in which the About one-seventh of the total production of heat- 25-20 base has been altered, the carbon content has resistant castings is HT alloy because of its value in been reduced and columbium (niobium) has been resisting thermal shock, its resistance to oxidation and added. As a result, the high-temperature stress-rupture carburization at high temperatures, and its good strength has been improved. It is used for centrifu- strength at heat treating furnace temperatures. Except gally-cast catalyst tubes in steam-hydrocarbon re- in high-sulfur gases, it performs satisfactorily up to former furnaces. 2100 ºF in oxidizing atmospheres and up to 2000 ºF in reducing atmospheres. It is used for load-bearing mem- bers in many furnace applications, retorts, radiant tubes, HL (30Cr-20Ni) cyanide and salt pots, hearth plates and trays quenched This alloy has excellent resistance to oxidation at with the work. temperatures over 2000 ºF, and is resistant to corrosion in flue gases containing a moderate amount of sulfur up HU (39Ni-18Cr) to 1800 ºF. It is used where higher strength is required This type has an exceptionally high combination of than obtainable with lower nickel content alloys. Leading creep strength and ductility up to 2000 ºF and is used applications are for radiant tubes, furnace skids and where high hot strength is required. It is suited for severe stack dampers where excessive scaling must be service conditions involving high stress and rapid thermal avoided, such as in enameling furnace carriers and cycling. HU alloy has good resistance to corrosion by fixtures. either oxidizing or reducing hot gases containing NICKEL-CHROMlUM-IRON ALLOYS moderate amounts of sulfur. Typical uses are heat treat- ing salt pots, quenching trays, fixtures and gas dissocia- The nickel-chromium-iron alloys are fully austenitic tion equipment. and contain 25 to 70% nickel and 10 to 26% chromium.

They can be used satisfactorily up to 2100 ºF because no brittle phase forms in these alloys. They have good HW (60Ni-12Cr) weldability and are readily machinable if proper tools The HW alloy performs satisfactorily up to 2050 ºF in and coolants are used. The specific types of alloys in strongly oxidizing atmospheres and up to 1900 ºF in this group are HN, HP, HT, HU, HW and HX. oxidizing or reducing products of combustion, provided These austenitic heat-resistant alloys have good hot that sulfur is low or not present in the gas. The adherent strength and good resistance to carburization and thermal nature of its oxide scale makes HW alloy suitable for fatigue. They are used widely for load-bearing appli- enameling furnace service where even small flecks of cations and for castings subject to cyclic heating and dislodged scale could ruin the work in process. High- large temperature differentials. They will withstand re- temperature strength, resistance to thermal fatigue and ducing and oxidizing atmospheres satisfactorily but high- resistance to carburization, are obtainable with this alloy sulfur atmospheres should be avoided. and its high electrical resistivity suits it for electrical

7 heating elements. Other applications are cyanide pots, CHROMIUM NICKEL ALLOYS gas retorts, hardening fixtures (quenched with the work), Chromium-Nickel Alloy (50Cr-50-Ni) hearth plates, lead pots, muffles and other parts in This alloy was developed to improve the resistance of cyaniding and carburizing operations. heat-resistant alloys to fuel oil ash. It is widely used

worldwide (and in fact is specified almost exclusively in HX (66Ni-17Cr) Europe) for resistance to oil ash corrosion in power The high-alloy content of this grade confers high re- plants, petroleum refinery heaters and marine boilers at sistance to hot gas corrosion even in the presence of temperatures up to about 1650 ºF. Its applications in- some sulfur and permits it to be used for severe service clude such parts as sidewall and roof hanger supports in- applications where corrosion must be minimized at tem- furnace radiant sections, tube sheets, re-radiation cone peratures up to 2100 ºF. It is used to great advantage tips in vertical furnaces and for burner parts. where maximum and widely fluctuating temperatures are encountered because of its ability to withstand cycling IN-657 (50Cr-48Ni-1.5Cb) without cracking or severe warping. Thus, a leading This more recent development is a columbium application is for quenching fixtures. It is also useful in (niobium) modification of the 50Cr-50Ni alloy also with carburizing and cyaniding equipment. Typical applica- high resistance to fuel oil ash corrosion but with creep tions in which it gives excellent service include nitriding, and stress-rupture properties superior to those of the carburizing and hardening fixtures (quenched with the 50Cr-50Ni alloy. IN-657 is used in petroleum refinery work), heat-treating boxes, retorts and burner parts. heaters, marine and land-based boilers in such applica- tions as convection section tube sheets; it is produced by several U.S. and European foundries under license from Inco.*

SELECTING THE PROPER ALLOY The selection of the proper cast alloy for a given properties that must be matched with them. Some of high-temperature application requires knowledge of these properties are listed below and are discussed various factors and the related mechanical and physical later under "Alloy Casting Design."

Operating Conditions Related Property 1. Anticipated service and maximum Short-time tensile properties temperature of operation Creep strength Stress-rupture properties Hot ductility 2. Type and size of maximum load Short-time tensile properties Creep strength Stress-rupture properties Hot ductility 3. Temperature cycling Thermal fatigue properties a. Range of temperature cycling b. Frequency of temperature cycling c. Rate of temperature change 4. Type of atmosphere or other corrosive Oxidation resistance conditions Carburization resistance Sulfidation resistance Surface stability 5. Size and shape of part Temperature gradients 6. Further processing, such as welding Fabrication data and machining 7. Abrasive or wear conditions – 8. Cost – 9. Ease of replacement –

The governing economic consideration in the selec- must also be considered in the selection of the alloy. tion of heat-resistant alloy castings is the cost per hour With rare exceptions, the use of heat-resistant alloys is at operating temperatures. Equipment downtime can justified at all temperatures above 1200 ºF. result in a loss of production that is far more expensive In selecting heat-resistant alloys for castings, the sig- than the cost of the alloy involved. Ease of replacement nificant properties that must be considered are shown in Tables II, III and IV.

*Trademark of the Inco family of companies.

8 HEAT-RESISTANT ALLOY CASTING DESIGN The properties listed in Table II and Figures 1 through plication of these properties in casting design together 4, inclusive, are the basis for the design of heat-resistant with other design considerations that are not amenable alloy castings. This selection is concerned with the ap- to tabulation.

TABLE II Room Temperature Mechanical Properties of Heat-Resistant Alloy Castings

Type I Type II IN- 50Cr- IN PROPERTY HA HC HD HE HF HH HH HI HK 519 HL HN HP HT HU HW HX 50Ni 657 Tensile Strength, ksi As-Cast 951 70 85 95 92 85 80 80 75 75 82 68 71 70 70 68 65 804 87 Aged 1072 115 – 90 100 86 92 90 85 – – – – 75 73 84 73 – – Yield Strength (0.2% offset), ksi As-Cast 651 65 48 45 45 50 40 45 50 353 52 38 40 40 40 36 36 504 543 Aged 812 80 – 55 50 55 45 65 50 – – – – 45 43 52 44 – – Elongation in 2 in., % As-Cast 231 2 16 20 38 25 15 12 17 25 19 13 11.5 10 9 4 9 15 28 Aged 212 18 – 10 25 11 8 6 10 – – – – 5 5 4 9 – – Brinell Hardness As-Cast 1801 190 190 200 165 185 180 180 170 – 192 160 – 180 170 185 176 – – 2 Aged 220 - – 270 190 200 200 200 190 – – – – 200 190 205 185 – – Aging Treatment - 24 hours – 24 hours 24 hours 24 hours 24 hours 24 hours 24 hours – – – – 24 hours 48 hours 48 hours 48 hours – – at at at at at at at at at at at 1400 ºF 1400 ºF 1400 ºF 1400 ºF 1400 ºF 1400 ºF 1400 ºF 1400 ºF 1800 ºF 1800 ºF 1800 ºF Furnace Furnace Furnace Furnace Furnace Furnace Furnace Air Air Furnace Air Cooled Cooled Cooled Cooled Cooled Cooled Cooled Cooled Cooled Cooled Cooled Modulus of Elasticity 29 29 27 25 28 27 27 27 27 23 27 27 27 27 27 25 25 – 30 in Tension, ksi x 103 1Annealed 2Normalized at 1825 ºF and tempered at 1250 ºF. 30.2% Proof Stress 4Minimum

HIGH-TEMPERATURE MECHANICAL PROPERTIES son of alloys, and Table III shows the data on this basis. This is sometimes expressed as 1 % creep in 10,000 hr. In common with all metals, the load-carrying ability of It should be kept in mind that when creep is expressed heat-resistant casting alloys decreases as the tempera- in the latter terms it does not mean that this rate of creep ture increases. However, the fall-off in strength is less can be expected to continue in every instance for 10,000 pronounced than it is with less highly alloyed materials. hours without failure. At elevated temperatures, metals under stress are Figure 1 and Table III compare the creep strengths subject to slow plastic deformation as well as to elastic of representative heat-resistant alloy castings. deformation. Therefore, time becomes a critical factor and conventional tensile tests do not furnish values that Creep values that are obtained under constant load are useful in design. The data required are those indica- and constant temperature conditions are applicable to ting the load which will produce no more than an allow- design, however, safety factors should always be incor- able percentage of elongation at a specified tempera- porated. The safety factor will depend on the degree to ture in a given period of time. Thus, the factors of time which the application is critical. and deformation as well as stress and temperature are involved in high-temperature strength properties. Stress-Rupture Properties Stress-rupture properties determined under constant Creep Strength load at constant temperature are useful in approximating The slow plastic deformation that occurs under load the life of the alloy (time to fracture) under the specific at elevated temperatures is known as creep. In the conditions and also for comparing alloys which are design of furnace parts, experience indicates that a subject to loading that might produce failure in a creep rate of 0.0001% per hr is satisfactory for compari- relatively short time.

9 TABLE III Elevated Temperature Properties of Heat-Resistant Alloy Castings

Type l Type II PROPERTY HA HC HD HE HF HH HH HI HK IN-519 HL HN HP HT HU HW HX 50Cr-50Ni IN-657 Short-Time Tensile Strength, ksi, at 1000 ºF 67 – – – – – – – – – – – – – – – – 446 866 1200 ºF – – – – 60 – 60.5 – – – – – – 42.4 – – 45 404 794 1400 ºF – – 36 – 38 33 37.4 38 37.5 391 50 – 43 35 40 32 – 361 681 1600 ºF – – 23 – 21 18.5 21.5 26 23.3 232 30.4 20.2 26 18.8 19.6 19 20.5 182 362 1800 ºF – – 15 – – 9 10.9 – 12.4 153 18.7 11.9 14.5 11 10 10 10.7 – – 2000 ºF – – – – – – 5.5 – 5.6 – 6.2 7.5 6 – – – – – Short-Time Yield Strength (0.2% Offset), ksi, at 1000 ºF 42 – – – – – – – – – – – – – – – – – 366 1200 ºF – – – – 31.5 – 32.2 – – – – – – 28 – – 20 – 464 1400 ºF – – – – 25 17 19.8 – 24.4 201 – – 29 26 – 23 – – 291 1600 ºF – – – – 15.5 13.5 16 – 14.7 132 – 14.5 17.5 15 – 15 17.5 – 152 1800 ºF – – – – – 6.3 7.3 – 8.7 93 – 9.6 11.0 8 6.2 8 6.9 – – 2000 ºF – – – – – – – – 5.0 – – 4.9 6.2 – – – – – – Elongation in

2 in., %, at 1000 ºF – – – – – – – – – – – – – – – – – 126 166 1200 ºF – – – – 10 – 14 – – – – – – 5 – – 8 44 154 1400 ºF – – 14 – 16 18 16 6 12 321 – – 15 10 – – – 31 151 1600 ºF – – 18 – 16 30 18 12 16 432 – 37 27 26 20 – 48 52 192 1800 ºF – – 40 – – 45 31 – 42 373 – 51 46 28 28 40 40 – – 2000 ºF – – – – – – – – 55 – – 55 69 – – – – – – Creep Stress

0.0001%/hr, ksi, at 1000 ºF 16 – – – – – – – – – – – – – – – – – – 1200 ºF 3.1 – – – 18 – 18 – – – – – – – – – – – 184 1400 ºF – 1.3 3.5 4 6.8 3 6.3 6.6 10.2 8.61 7.0 – – 8 8.5 6 6.4 – 6.51 1600 ºF – 0.75 1.9 2.4 3.9 1.7 3.9 3.6 6.0 4.52 4.3 6.3 5.8 4.5 5.0 3 3.2 – 2.52 1800 ºF – 0.36 0.9 1.4 – 1.1 2.1 1.9 2.5 1.83 2.2 2.4 2.8 2 2.2 1.4 1.6 – 0.53 2000 ºF – – 0.2 0.4 – 0.3 0.8 0.8 0.65 – – 1.0 1.0 0.5 0.6 – 0.6 – – 2150 ºF – – – – – – – 0.15 – – – – – 0.15 – – – – – Stress to Rupture

in 100 hr, ksi, at 1000 ºF 37 – – – – – – – – – – – – – – – – – – 1200 ºF – – – – 33 – 35 – – – – – – – – – – – 304 1400 ºF – 3.3 10 11 13.5 14 14 13 15.5 141 15.0 – – 16 15 10 13 – 14.51 1600 ºF – 1.7 5 5.3 7.2 6.4 6.8 7.5 9.2 92 9.2 11 10 8.9 8 6 6.7 – 7.22 1800 ºF – 0.85 2.5 2.5 – 3.1 3.2 4.1 4.7 53 5.2 5.6 5.9 4.4 4.5 3.6 3.5 – 3.83 2000 ºF – – – – – 1.5 1.4 1.9 2.2 – – 2.9 2.8 2.1 – – 1.7 – 1.65

11470 ºF 41290 ºF 21650 ºF 52010 ºF 31830 ºF 61110 ºF

Ductility An accurate comparison of hot ductility of heat- Stress-rupture properties are a valuable adjunct to resistant casting alloys is difficult since there is no gen- creep-strength values in the selection of heat-resistant erally accepted reference test. Total elongation values casting alloys and in the establishment of allowable on both creep and stress-rupture tests are often used design stresses. Figures 2, 3, and 4 compare the stress- as criteria. Also, the elongation in short-time high- rupture properties of representative casting alloys for temperature tensile tests is commonly used in specifica- various time periods. Frequently, designers of furnaces tions as an indication of high-temperature ductility. In and furnace tubing use the 100,000-hour stress-rupture many applications where castings are handled at normal properties with some factor of safety. A comparison of temperatures, room temperature ductility is a con- Figures 1 and 2 shows that, in general, stress-rupture sideration. Heat treating to remove sigma phase by tests rank the alloys in much the same order as the heating castings to 1800 ºF and cooling to below 1200 ºF creep tests. improves ductility.

10

Figure 1– Creep Strength of Heat-Resistant Alloy Castings (HT curve is included in both graphs for ease of comparison).

11

Figure 2 –1,000-Hour Stress-Rupture Properties of Heat-Resistant Alloy Castings (HT curve is included in both graphs for ease of comparison).

12

Figure 4–100,000-Hour Stress-Rupture Properties of Several Heat-Resistant Alloy Castings.

13 Short-Time Tensile Properties mining the life of castings in service. For this reason, the Short-time hot-tensile tests in which the test speci- heat-resistant casting user should consult with the pro- men is held at the test temperature for one hour and ducers in the early stages of design in order to obtain the then pulled at temperature, cannot be relied upon to benefit of their experience with similar applications. indicate how heat-resistant alloys will behave in service. The values obtained are as much as five or six times DESIGN DATA the limiting creep stress values, and, therefore, greatly over-evaluate load-carrying ability over long periods of The curves shown in Figure 5 are constructed to time. Nevertheless, short-time tensile tests can be help- indicate the values of allowable stress that result from ful in evaluating resistance to momentary overloads and applications of code criteria to the short-time tensile, are included in some specifications. The short-time creep, and stress-rupture properties of the heat- mechanical properties for the standard heat-resistant resistant alloys, HF, HH-II, HK and HN. The ASME alloys are given in Table Ill. Boiler Code allowable stresses for wrought composi- tions are included in two of the graphs to offer a compari- Thermal Fatigue son.

In many high-temperature applications, intermittent or widely fluctuating temperatures (cyclic heating) are HIGH-TEMPERATURE CORROSION encountered, and therefore the ability of the various heat-resistant casting alloys to withstand such thermal RESISTANCE fatigue service must be considered. High-temperature equipment is exposed to many dif- Thermal fatigue failure involves cracking caused by ferent atmospheres and corrosive conditions and an heating and cooling cycles. Crazing and checking of important requirement of heat-resistant alloys is surface heat-treating fixtures are typical examples. Such fail- film stability. No single alloy will show satisfactory resis- ures are the result of many reversals of thermal stresses tance to all of the high-temperature environments. in the part as contrasted to common mechanical fatigue High-temperature corrosive conditions may involve failures, which are caused by externally applied loads. simple oxidizing or reducing atmospheres or they may be Very little experimental thermal fatigue information is complicated by sulfur compounds in the products of available on which comparison of the various alloys can combustion. Oxidizing flue gases are slightly more cor- be based, and no standard test as yet has been rosive than air if the sulfur concentration is low. Corro- adopted. Field experience indicates that, usually, resis- sive attack by reducing flue gases is similar to that of an tance to thermal fatigue is improved with increasing oxidizing gas if the sulfur content is not greater than 100 nickel content. Columbium-modified ACI alloys have ppm. At higher sulfur concentrations, attack by reducing been employed successfully where a high degree of gas is much more severe. The high nickel alloys, types thermal fatigue resistance is desired such as in reformer HN to HW, give good service under oxidizing and reduc- outlet headers. ing conditions if the sulfur content of the gas is low. Types HH and HL, for example, should be considered Temperature Gradients for service in sulfur-bearing atmospheres. Non-uniform heating or cooling causes temperature Cyclic heating under reducing conditions increases gradients and the attendant unequal dimensional metal loss in alloys containing from 10 to 50% nickel. changes result in stresses within the casting, These Under oxidizing conditions, cyclic heating has little ef- stresses may be accompanied, particularly at high tem- fect in alloys containing more than 20% nickel. peratures, by some degree of plastic deformation. The Different corrosive conditions are encountered with magnitude of the stress and/or the amount of the plastic equipment in contact with fused salts or molten metals. deformation will depend on the temperature differential Types HT to HX should be considered for service under within the casting. these conditions. Still other conditions are met in the Heat-resistant alloys inherently have high coefficients chemical, petroleum, and petrochemical industries of thermal expansion and low heat conductivity, both where new processes with new corrosive conditions are properties tending to produce temperature and stress constantly under development. differences between various regions of a casting. The In the heat-treating industry, only the high nickel- unequal stresses set up within the casting tend to distort chromium alloys give satisfactory service under nitriding or fracture it; thus, maximum articulation should be de- conditions. Another important process in the heat- signed into elevated temperature parts by making them treating industry is carburization, which is considered in of a number of small components that are free to expand some detail below. and contract. All sharp corners and abrupt changes in section are to be avoided. Carburization Resistance Proper design, taking all thermal conditions into con- When heat-resistant castings are used as muffles, sideration, is as important as alloy composition in deter- holding fixtures or baskets for work being carburized,

14

Figure 5–Design Data for Four Heat-Resistant Steels.

15 the castings also pick up carbon. The same effect oc- con content should be kept on the high side. Carburiza- curs in any high-temperature carbon-bearing atmo- tion resistance of types HH and HK is improved with sphere under reducing conditions. Some alloys absorb silicon content above 1.6%. from 0.30 to 2% carbon within a period of several months when used in a carburizing application. A large increase in carbon pickup leads to volume changes ROOM TEMPERATURE PROPERTIES which can cause warpage and distortion. The additional The room temperature properties of the various carbon also leads to difficulties if repair welding of the alloys shown in Table II have little relationship to high- casting is necessary. Increasing the nickel content re- temperature behavior. These properties are useful only duces the effect of increased carbon content on the for acceptance purposes and for instances where the mechanical properties of heat-resistant alloys. Hence, nature of the service requires good strength at room the nickel-chromium-iron grades HP to HX are preferred temperature. because they withstand thermal fatigue and shock load- Acceptance tests of a particular composition at room ing at higher carbon levels than alloys with less nickel. temperature are used only with the supposition that the Resistance to carbon penetration increases as the alloy will behave at elevated temperatures in the same nickel content increases and to some extent as the way that the same composition has behaved previously chromium content increases. Therefore the high nickel in the same application. types HP to HX are all good in this respect with the HW The room temperature properties after aging are and HX types, being highest in nickel content, rating as given as an indication of the structural stability of the excellent. alloy after high-temperature exposure. The high chromium types are generally not suitable The physical properties of the heat-resistant alloys for service under carburizing conditions unless other are given in Table IV. requirements dictate their selection. In such cases, sili-

TABLE IV Physical Properties of Heat-Resistant Alloy Castings

Type Type l II IN- 50Cr- IN Property HA HC HD HE HF HH HH HI HK 519 HL HN HP HT HU HW HX 50Ni 657 Density, lb/cu in. 0.279 0.272 0.274 0.277 0.280 0.279 0.279 0.279 0.280 0.286 0.279 0.283 0.284 0.286 0.290 0.2940.294 0.291a 0.288 Mean Coefficient of Linear Thermal Expansion, in./in./° F x 10-6 70 - 212 ºF 6.1 ------7.21 - - - 7.9 - 7.0 - - 5.91 70 - 1000 ºF 7.1 6.3 7.7 9.6 9.9 9.5 9.5 9.9 9.4 9.12 9.2 9.3 9.2 8.8 8.8 7.9 7.8 7.42 70- 1200 ºF 7.5 6.4 8.0 9.9 10.1 9.7 9.7 10.0 9.6 - 9.4 9.5 9.5 9.1 9.0 8.2 8.1 - 70 - 1400 ºF - 6.6 8.3 10.2 10.3 9.9 9.9 10.1 9.8 9.33 9.6 9.7 9.8 9.3 9.2 8.5 8.5 8.33 70 - 1600 ºF - 7.0 8.6 10.5 10.5 10.2 10.2 10.3 10.0 9.44 9.7 9.9 10.0 9.6 9.4 8.7 8.8 8.34 70 - 1800 ºF - 7.4 8.9 10.8 10.6 10.5 10.5 10.5 10.2 9.55 9.9 10.1 10.3 9.8 9.6 9.0 9.2 8.25 70 - 2000 ºF - 7.7 9.2 11.1 10.7 10.7 10.7 10.8 10.4 - 10.1 10.2 10.6 10.0 9.7 9.3 9.5 - 1200 - 1600 ºF - 8.7 10.3 12.2 11.5 11.4 11.4 11.0 - - 10.5 - 11.4 10.8 10.5 10.0 10.7 - 1200 - 1800 ºF - 9.3 10.6 12.5 - 11.7 11.7 12.0 11.4 - 10.7 11.0 11.9 11.0 10.6 10.3 11.3 - Specific Heat, Btu/Ib/° F at 70 ºF 0.11 0.12 0.12 0.14 0.12 0.12 0.12 0.12 0.13 0.11 0.12 0.11 0.11 0.11 0.11 0.11 0.11 - 0.11 Specific Electrical Resistance, microhm-cm at 70 ºF 70 77 81 85 80 75-85 75-85 85 90 978 94 99.1 102 100 105 112 116 - 988 Thermal Conductivity, Btu/hr/sq ft/ft/°F At 212 ºF 15.0 12.6 12.6 8.5 8.3 8.2 8.2 8.2 7.9 8.2 8.2 7.5 7.5 7.0 7.0 7.2 7.2 - 8.2 At 1000 ºF 15.7 17.9 17.9 12.4 12.3 12.0 12.0 12.0 11.8 12.96 12.2 11.0 11.0 10.8 10.8 11.1 11.1 13.46 At 1400 ºF - - - 14.6 14.6 14.1 14.1 14.1 14.2 - 14.7 13.2 13.2 12.9 12.9 13.3 13.3 - At 1500 ºF - 20.3 20.3 ------14.87 ------15.57 At 2000 ºF - 24.2 24.2 18.2 - 17.5 17.5 17.5 18.6 - 19.3 17.0 17.0 16.3 16.3 17.0 17.0 - Melting Point (approx), ºF 2750 2725 2700 2650 2550 2500 2500 2550 2550 2490 2600 2500 2450 2450 2450 2350 2350 - 2400 Magnetic Permeability Ferro- Ferro- Ferro- 1.3-2.5 1.00 1.0-1.9 1.0-1.05 1.0-1.7 1.02 - 1.01 1.10 1.02-1.25 1.10-2.00 1.10- 16.0 2.0 - - Magnetic Magnetic Magnetic 2.00

168- 212 ºF 61110 ºF 268- 930 ºF 71470 ºF 368-1470 ºF 8 75 ºF 468-1650 ºF aCalculated 568-1830 ºF

16 Industrial Applications of Heat-Resistant Alloy Castings

AERONAUTICAL Typical Applications

The high temperatures encountered in aircraft power plants Jet engine rotors Afterburner parts and afterburners have been controlled by the use of heat- Jet engine rings Gun blast tubes resistant alloy castings.

CEMENT In kiln processes, heat, corrosion and abrasion are con- stantly attacking operating equipment. High-alloy castings resist high temperatures, corrosive gases and abrasives and reduce breakage, shut-down time and rapid wear.

Typical Applications Burner nozzles Kiln end rings Conveyors Kiln feed chutes Cooler lifters Kiln shell segments Dampers Slurry feed pipes Kiln chains CONTINUOUS CAST CHAIN Alloy: HH (25Cr-12Ni) Weight: 50 Ib Use: Cement Kiln

GLASS AND ENAMELING In the glass, pottery and enameling industries, handling equipment must have sufficient strength at elevated tempera- tures to resist bending and warpage. The alloys used must LEHR ROLLS resist scaling or flaking to prevent contamination of the prod- Alloy: HF (19Cr-9Ni) Weight: 1040 Ib uct. Some heat-resistant cast alloys have both these charac- Size: 8 in. O.D., 6 in. I.D., 168 in. long teristics and they are used extensively. Use: Supports glass without bending at operating temperature of 1500 ºF. Typical Applications

Trays Brick supports Molds Suspension bars Fixtures Hearth plates Hangers Kilns and furnaces Burning tools Lehr rolls

17 Glass and Enameling (Cont'd.)

MUFFLER ASSEMBLIES Alloy: HT (35Ni-15Cr) Size: Each casting 24 in. long, wall thickness ¼ in. Use: Handle hot gases (1750-1800 ºF) of glassmaking furnace.

ENAMELING FURNACE FLOOR IRONS Alloy: HT (35Ni-15Cr) Weight: 575 Ib (large casting) Use: Operates at 1800 ºF

HEAT TREATING The advantages of high-alloy castings have been frequently castings for long uninterrupted service and low maintenance demonstrated in heat-treating equipment. High temperatures, and operating costs. The uses of high-alloy castings in heat- heavy loads, thermal shock and the continuous operation of treating operations are extensive. heat-treating furnaces require the use of heat-resistant alloy

Typical Applications Trays Roller conveyors Boxes and baskets Screw conveyors Retorts Skid rails Fixtures Hot fans Conveyor belts and chains Molten metal pots Furnace hearths Furnace muffles Furnace hearth supports Radiant tubes Roller rails Dampers Grates Heat exchangers

SHAFT FIXTURE ON TRAY Alloy: HU (39Ni-15Cr) Weight: 87 Ib Use: Carburizing furnace

18 Heat Treating (Cont'd.)

GEAR FIXTURE ON TRAY Alloy: HU (39Ni-18Cr) Weight: 75 Ib TRAY WITH CRISS-CROSS FIXTURE Use: Carburizing furnace Alloy: HU (39Ni-18Cr) Weight: 56 Ib Use: Carburizing furnace

RIVETLESS CHAIN Alloy: HW (60Ni-12Cr) Weight: 5 lb each Size: 5 in. x 6 in. x 1¾in. Use: Convey parts through hardening furnace operating at 1650 ºF.

TRAY ARTICULATED TRAY WITH TUBULAR FIXTURE Alloy: HU (39Ni-18Cr) Alloy: HX (66Ni-17Cr) Weight: 40 lb Weight: 178 lb Use: Roller rail furnace Use: Solution treat aircraft parts (water quenched).

19 GRID WITH LIFTING LOOPS TUBULAR GRID ROLLER TRAY Alloy: HU (39Ni-18Cr) Alloy: HT (35Ni-17Cr) Weight: 265 lb Weight: 164 lb Use: Pit furnace top support Use: Malleablizing furnace

TUBULAR BASE WITH GRIDS Alloy: HT (35Ni-17Cr) Weight: 1170 lb Use: Pit furnace base support

SIDE HEARTH LINK BELT Alloy: HH (25Cr-12Ni) Weight: According to size Size: 3 in., 4 in., or 6 in. pitch Use: Convey parts through continuous furnaces operating at 1600 to 1800 ºF

20

PIT FIXTURE WITH SPACER GRIDS Alloy: HT (35Ni-17Cr) PIT FIXTURE CAGE Weight: 1173 Ib Alloy: HX (66Ni-17Cr) Use: Carburizing furnace Weight: 930 Ib Use: Solution treat space parts.

PIT FURNACE RING Alloy: HX (66Ni-17Cr) Weight: 849 Ib Use: Solution treat space parts (water quenched).

TRAY WITH TWO CRISS-CROSS FIXTURES Alloy: HU (39Ni-18Cr) Weight: 115 Ib Use: Carburizing furnace

21 PETROLEUM, PETROCHEMICAL REFINING AND CHEMICAL The heat-resistant grades of high-alloy castings are used high output operation under severe corrosive and temperature extensively in the petroleum refining industry. High-pressure conditions. and high-temperature refining units depend on high-alloy sup- ports, tubes, headers and other castings which can withstand excessive heat and corrosion. Metal parts used in refineries and rectifying plants are subject to extreme temperatures, Typical Applications heavy loadings, and corrosive liquids and gases. Among heat- Beams and channels Tube sheets resistant alloy casting grades are those that assure protection Pumps Tubes from deterioration caused by heating and cooling cycling and Valves Tube supports and wall ties resist corrosive media at temperatures up to 2000 ºF. HK-40 Pistons Heater tubes and IN-519 are used extensively for catalyst tubes in steam- Retorts Fittings hydrocarbon reforming furnaces. The chromium-nickel alloys, Roof tube hangers Burners and nozzles 50Cr-50Ni and IN-657, show excellent resistance to fuel oil Dampers ash attack and are used extensively in Europe to resist this material. High-alloy castings serve many applications in the chemical equipment field where heat-resistant castings are permitting

U-BEND RETURN Alloy: HK-40 (25Cr-20Ni) Weight: 45 Ib Size: 4 in. O.D. x 10 in. center to center Use: Ethylene converter furnace CAST WELDING WYE Alloy: HP (35Ni-26Cr) Weight: 74 lb Size: 14 in. long, 10 in. center to center Use: Pyrolysis furnace FLANGES AND REDUCERS Alloy: HF with 5-15% ferrite (19Cr-9Ni) Weight: 1500 lb (flanges) Use: High temperature piping in petrochemical plant.

22 FURNACE TUBE ASSEMBLIES Alloy: HP (35Ni-26Cr) Weight: 500 lb per assembly Size: 3.75 in. O.D. x 3.12 in. I.D. x 20 ºFt long Use: Coil, radiant section, pyrolysis furnace

WELD ELBOW WITH TRUNNION PAD Alloy: HK-40 modified with Cb (25Cr-20Ni-Cb) Weight: 23 Ib Size: 4 in. O.D. x 3 in. ID Use: Ethylene converter furnace

VERTICAL TUBULAR BEAM WITH LOOSE ACCESSORIES Alloy: HK (25Cr-20Ni) Weight: 153 Ib Use: Petrochemical tube support TUBE SUPPORT Alloy: HH (25Cr-12Ni) Weight: 15 Ib Use: Petrochemical industry

23 TUBE SUPPORTS Alloy: HH (25Cr-12Ni) Weight: 6 Ib Use: Petrochemical industry

SIDE SUPPORTS AND TUBE SHEETS Alloy: HK (25Cr-20Ni) Weight: Sheets, 170 lb; supports, 407 lb

HORIZONTAL TUBULAR BEAM WITH ACCESSORIES HORIZONTAL TUBULAR BEAM WITH ACCESSORIES Alloy: HK (25Cr-20Ni) Alloy: HK (25Cr-20Ni) Weight: 253 Ib Weight: 299 Ib Use: Petrochemical tube support Use: Petrochemical tube support

24 REDUCING ELBOW Alloy: HK-40 (25Cr-20Ni) Weight: 10 Ib Size: I.D. reduction 4½ in. to 1½ in. Use: Reformer tube assemblies BURNER DIFFUSER Alloy: HX (66Ni-17Cr) Weight: 27 Ib Use: Petrochemical industry

CENTRIFUGALLY-CAST FURNACE TUBE Alloy: HK-40 (25Cr-20Ni) Weight: 245 Ib Size: 4 in. O.D. x 3 in. I.D. x 156 in. long Use: Furnace tube section

BURNER NOZZLES POWER PLANTS Alloy: HE (29Cr-9Ni) Weight: 10 to 15 lb each Because of the higher operating temperatures being used Use: Burners operating at temperatures up to 1800 ºF in superheater and boiler units, extensive use is being made of heat-resistant cast alloys. The proper use of high-alloy castings avoids costly shutdowns and reduces maintenance requirements

Typical Applications

Tube supports Nozzles Hanger bolts Beams Brick and tile supports Burner diffusers Dampers Valve bodies

25 STEEL MILL EQUIPMENT The advantages of heat-resistant alloy castings have been demonstrated by the steel industry in many high-temperature applications. These alloys are capable of operation at high speeds, temperatures and loads and provide reliable opera- tion for long periods, thus reducing equipment upkeep and operating costs.

Typical Applications FURNACE DRUM Baffles Retorts Alloy: HK-40 (25Cr-20Ni) Furnace beams and rails Radiant tubes Weight: 10,000 Ib Conveyor parts Recuperators Size: 60 in. major O.D. Furnace doors and frames Skid rails Use: Turn-down roll in steel mill furnace for normalizing sheet. Dampers Muffles

GUIDES Alloy: HH (25Cr-20Ni) Weight: 2 and 14 Ib Use: Steel rod mill guides

REFRACTORY-LINED BLOWPIPES Alloy: HP (35Ni-26Cr) Weight: 600 Ib (pipe) Size: 10 in. O.D. barrel with 14 in. O.D. bell ends Use: Steel mill blast furnace

SMELTING AND REFINING EQUIPMENT Typical Applications Many years ago, this industry recognized the savings that Rabble arms Feed spouts were possible if high-alloy castings were properly utilized. In Plows Hearth plates the sintering and smelting of ores, high temperatures, acid Rabbles Lute rings gases and abrasion contribute to the destruction of furnace, Air arms Grate hearth, kiln and sintering machine parts. Heat-resistant alloy Chains Seal plates castings reduce operating and maintenance costs by provid- ing durability and heat resistance. Dampers Furnace tubes

COOLER GRATES GRATE BARS Alloy: HH (25Cr-12Ni) Alloy: HH (25Cr-12Ni) Weight: 20 to 40 Ib Weight: 12 Ib Use: Iron ore pelletizing and cement kiln Use: Iron ore sintering and pelletizing furnace

26

Part ll Corrosion-Resistant Alloy Castings

The corrosion-resistant casting alloys are those com- VI, the physical properties in Table VII and the heat positions capable of performing satisfactorily in a large treating temperatures in Table VIII. variety of corrosive environments. They are composed Commercial cast corrosion-resistant alloy can be principally of nickel, chromium and iron; sometimes also identified by the designations of the Alloy Casting Insti- containing other elements. Castings made of these al- tute, now a division of the Steel Founders' Society of loys offer two basic advantages: America, and the American Society for Testing and 1. Facility of the production of complex shapes at Materials.* Some of these materials are also listed in the low cost. Aerospace Material Specifications (AMS) of the Society 2. Ease of securing rigidity and high strength-to- of Automotive Engineers, the United States Govern- weight ratios. ment Specifications (MIL and QQ), the Society of Auto- Some typical alloy compositions are given in Table V, motive Engineers Specifications and the Unified Num- the room temperature mechanical properties in Table bering System (UNS) developed by the Society of Auto- motive Engineers and the American Society for Testing and Materials. TABLE V Compositions of Corrosion-Resistant Alloy Castings

AISI CHEMICAL COMPOSITION, % Alloy Casting ASTM (or other) Institute Alloy (or other) Wrought UNS Ni Cr Mo Cu C Mn Si Other Designation Type Specification Comparative No. Max Max Max

CA-15 12Cr A296, A487 410 J91150 1.0 11.5-14.0 0.5 – 0.15 1.00 1.50 Fe bal CA-40 12Cr A296 420 J91153 1.0 11.5-14.0 0.5 – 0.20-0.40 1.00 1.50 Fe bal CA-6NM 12Cr-4Ni A296,A487 – J91540 3.5-4.5 11.5-14.0 0.40-1.0 – 0.06 1.00 1.00 Fe bal CA-6N1 12Cr-7Ni A296 – – 6.0-8.0 10.5-12.5 – – 0.06 0.50 1.00 Fe bal CB-30 20Cr A296 442 J91803 2.0 18-22 – – 0.30 1.00 1.50 Fe bal CB-7Cu-1 17Cr-4Ni A747 17-4PH2 – 3.6-4.6 15.5-17.7 – 2.5-3.2 0.07 0.70 1.00 Cb 0.20-0.35; N 0.05 max; Fe bal CB-7Cu-2 15Cr-5Ni A747 15-5PH2 – 4.5-5.5 14.0-15.5 – 2.5-3.2 0.07 0.70 1.00 Cb 0.20-0.35: N 0.05 max; Fe bal CC-50 28Cr A296 446 J92615 4.0 26-30 – – 0.50 1.00 1.50 Fe bal CD-4MCu 26Cr-5Ni A296 – – 4.75-6.0 25-26.5 1.75-2.25 2.75-3.25 0.04 1.00 1.00 Fe bal CE-30 29Cr-9Ni A296 312 J93423 8-11 26-30 – – 0.30 1.50 2.00 Fe bal CF-3 19Cr-10Ni A296, A351 304L J92500 8-12 17-21 – – 0.03 1.50 2.00 Fe bal CF-8 19Cr-9Ni A296, A351 MIL-S-867 304 J92600 8-11 18-21 – – 0.08 1.50 2.00 Fe bal CF-20 19Cr-9Ni A296 302 J92602 8-11 18-21 – – 0.20 1.50 2.00 Fe bal CF-3M 19Cr-10Ni A296, A351 316L J92800 9-13 17-21 2.0-3.0 – 0.03 1.50 1.50 Fe bal CF-8M 19Cr-10Ni A296, A351 316 J92900 9-12 18-21 2.0-3.0 – 0.08 1.50 1.50 Fe bal CF-8C 19Cr-10Ni A296, A351 347 J92710 9-12 18-21 – – 0.08 1.50 2.00 Cb 8XC min, 1.0 max or Cb-Ta 9XC min,

1.1 max; Fe bal CF-16F 19Cr-10Ni A296 303 J92701 9-12 18-21 1.50 – 0.16 1.50 2.00 Se 0.20-0.35; Fe bal CG-8M 19Cr-10Ni A296 MIL-S-867 317 J93000 9-13 18-21 3.0-4.0 – 0.08 1.50 1.50 Fe bal CH-20 25Cr-12Ni A296, A351 309 J93402 12-15 22-26 – – 0.20 1.50 2.00 Fe bal CK-20 25Cr-20Ni A296, A351 AMS 5365 310 J94202 19-22 23-27 – – 0.20 1.50 2.00 Fe bal CN-7M 20Cr-29Ni A296, A351 – J95150 27.5-30.5 19-22 2.0-3.0 3.0-4.0 0.07 1.50 1.50 Fe bal IN-8623 – – – – 23-25 20-22 4.5-5.5 – 0.07 1.50 1.00 Fe bal CW-12M1 – A296, A494 – – bal 15.5-20.0 16.0-20.0 – W 5.25 max; V 0.40 0.12 1.00 1.50 max; Fe 7.50 max CY-401 Ni-Cr-Fe A296, A494 INCONEL4 alloy 600 – bal 14.0-17.0 – – 0.40 1.50 3.00 Fe 11.0 max Alloy 6253 – – – – bal 20-23 8.0-10.0 – 0.06 1.00 0.75 Cb 3.15-4.50; Fe 5.0 max CZ-1001 Ni A296, A494 Nickel 200 – bal – – 1.25 1.0 1.50 2.00 Fe 3.0 max M-351 Ni-Cu A296, A494 MONEL4 QQ-N-288 alloy 400 – bal – – 26.0-33.0 0.35 1.50 2.00 Fe 3.50 max N-12M1 Ni-Mo A296, A494 – – bal 1.00 26.0-33.0 – 0.12 1.00 1.00 V 0.60 max; Fe 6.0 max – Ni-Si – – – bal 1.00 – 2.4 – 0.50-1.25 8.5-10.0 W 1 max

1ASTM designation 3INCO designation 2Trademark of Armco Steel Corporation 4Trademark of the INCO family of companies

Note: ASTM A.296 will be replaced by two new standards, A 743 and A 744 in the 1978 Annual Book of ASTM Standards. A 743 will cover the martensitic and ferritic types and A 744 the austenitic types. A 296 will appear in the 1978 Book of Standards but will be dropped in the 1979 Book.

*See ASTM Specification A 296

27 TABLE VI Room Temperature Mechanical Properties of Corrosion-Resistant Alloy Castings

CA- CA CB- CB- CD- CF- IN- CW- Alloy CZ- PROPERTY CA-15 CA-40 6NM -6N CB-30 7Cu-1 7Cu-2 CC-50 4MCu CE-30 CF-3 CF-8 CF-20 CF-3M CF-8M F-8C 16F CG-8M CH-20 CK-20 CN-7M 862 12M CY-40 625 100 M-35 N-12M

Tensile 2001 2201 1205 1406 957 17012a 17012a 70 8a 1089 9510 7711 7711 7711 8011 8011 7711 7711 8211 8811 7611 6911 60 726 65-9010 706 50-6510 65-8510 726 Strength, 1352 1502 15012b 15012b 95 8b 9711 ksi 1153 1403 14512c 14512c 1004 1104 13512d 13512d 12512e 12512e Yield 1501 1651 1005 1356 607 14512a 14512a 65 8a 829 4510 3611 3711 3611 3811 4211 3811 4011 4411 5011 3811 3211 25 466 32-5010,13 406 15-3010,13 30-4010,13 466 Strength 1152 1252 14012b 14012b 60 8b 6311 (0.2% offset) 1003 1133 11512c 11512C ksi 754 674 11012d 11012d 9712e 9712e

Elongation 71 11 245 156 157 512a 512a 2 8a 259 1510 6011 5511 5011 5511 5011 3911 5211 4511 3811 3711 4811 40 46 20-1010 206 30-1510 50-2510 66 in 2 in., % 172 102 912b 912b 15 8b 1811 223 143 912c 912c 304 184 912d 912d 1012e 1012e

1 1 5 7 12a 12a 8a 9 10 11 11 11 11 11 11 11 11 11 11 11 10 90– 10 Brinell 390 470 269 – 195 375 375 212 253 190 140 140 163 150 156–170 149 150 176 190 144 130 130 – 150–200 – 10 125–170 – 130 Hardness 2602 3102 31112b 31112b 193 8b 19011 2253 2673 27712c 27712c 1854 2124 26912d 26912d 26912e 26912e Modulus of 29 29 29 29.5 29 28.5 – 29 29 25 28 28 28 28 28 28 28 28 28 29 24 – – 23 – 21.5 23 – Elasticity, ksi x 103

9 1 Solution annealed at 2050 ºF. Water quenched from 1900 ºF. Air cooled from 1800 ºF. Tempered at 600 ºF. 10 2 As cast Air cooled from 1800 ºF. Tempered at 1100 ºF. 11 3 Water quenched from 2000-2050 ºF. Air cooled from 1800 ºF. Tempered at 1200 ºF. 12 4 a PH heat treatment H900, minimum values. Air cooled from 1800 ºF. Tempered at 1400 ºF. 5 b PH heat treatment H1025, minimum values. Air cooled from above 1750 ºF. Tempered at 1100-1150 ºF. 6 c PH heat treatment H1075, minimum values. Minimum 7 d PH heat treatment H1100, minimum values. Annealed at 1450 ºF. F.C. to 1000 ºF, then air cooled. e PH heat treatment H1150, minimum values. 8 a Under 1% Ni 13 0.5% extension b Over 2% Ni with 0.15 Nitrogen, minimum

TABLE VII Physical Properties of Corrosion-Resistant Alloy Castings

CA- CB- CB- CD- CF- CF- CF- CF- CF- CG- CH- CK- CN- IN- CW- Alloy- CZ- N- PROPERTY CA-15 CA-40 6NM CA-6N CB-30 7Cu-1 7Cu-2 CC-50 4MCu CE-30 CF-3 CF-8 20 3M 8M 8C 16F 8M 20 20 7M 862 12M CY-40 625 100 M-35 12M Density, Ib/cu in. 0.275 0.275 0.278 0.280 0.272 0.280 0.269a 0.272 0.280 0.277 0.280 0.280 0.280 0.280 0.280 0.280 0.280 0.280 0.279 0.280 0.289 0.292a0.336 a 0.300 0.305 0.301 0.312 0.334a Specific Heat, Btu db/°F at 70 0.11 0.11 0.11 - 0.11 0.11 - 0.12 0.11 0.14 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.11 - - 0.11 0.10 0.13 0.13 - ºF Mean Coefficient of Linear Thermal Expansion, in./in./°F x 106 70 - 212 ºF 5.5 5.5 6.0 5.7 6.0 - 5.9 6.3 - 9.0 9.0 9.6 8.9 8.9 9.3 9.0 8.9 8.6 8.3 8.6 - - - 7.1 - - - 70 - 1000 ºF 6.4 6.4 7.0 6.21 6.5 6.4 6.9 9.6 10.010.0 10.4 9.7 9.7 10.3 9.9 9.7 9.5 9.4 9.7 - 7.8 - 70 - 1200 ºF - - - - - 7.0 9.9 - 10.2 ------8.2 - 70 - 1300 ºF 6.7 6.7 - 6.7 ------70 - 1400 ºF ------10.2 ------8.9 8.5 8.9 70 - 1600 ºF ------10.5 ------8.8 - Specific Electrical Resistance microhm cm at 70 ºF 78 76 78 - 76 77 - 77 75 85 76.2 76.2 77.9 82 82 71 72 82 84 90 89.6 - - 116 129 21 53 - Thermal Conductivity, Btu/hr/sq ft/ft/°F at 212 ºF 14.5 14.5 14.5 - 12.8 9.9 - 12.6 8.8 8.5 9.2 9.2 9.2 9.4 9.4 9.3 9.4 9.4 8.2 7.9 12.1 - - 8.7 6.3 34 15.5 - at 1000 ºF 16.7 16.7 16.7 14.5 17.9 13.4 12.4 12.1 12.1 12.1 12.3 12.3 12.8 12.3 12.3 12.0 11.8 - 10.0 Melting Point _ _ (approx), ºF 2750 2725 2750 - 2725 2750 - 2725 2700 2650 2650 2600 2575 2600 2550 2600 2550 2550 2600 2600 2650 - - 2600 2460 2600 2400 - Magnetic Ferro- Ferro- Ferro- Ferro Ferro- - Ferro- Ferro- over 1.20- 1.00- 1.50- 1.50- 1.20- 1.00- 1.50- 1.01- – Permeability Magnetic Magnetic Magnetic Magnetic Magnetic Magnetic Magnetic 1.5 3.00 1.30 1.01 3.00 250 1.80 2.00 3.00 1.71 1.02 1.10 1.00

170-600 ºF 2Data from wrought equivalent aCalculated

28 The Alloy Casting Institute and ASTM designations bering System, Jxxxx number series has been assigned use "C" to indicate alloys used primarily for their to cast steels. corrosion-resistant properties. The second letter indi- The chemical compositions of the corrosion-resistant cates the nominal nickel content, increasing from A to Z. casting alloys are not the same as those of the wrought The S.A.E. specifications use the nearest wrought alloys. Therefore, Table V lists only the nearest AISI or composition (AISI type number) and prefix it with the other wrought comparative. Alloy Casting Institute des- number 60 ºFor corrosion-resistant castings; for exam- ignations or their equivalent should always be used to ple, 60304 is equivalent to CF-8. In the Unified Num- identify castings.

TABLE VIII Heat Treatment of Corrosion-Resistant Alloy Castings

Alloy Casting Institute Designation Anneal at Harden at Temper at Quench CA-15 1450-1650 ºF 1800-1850 ºF 600 ºF, max or 1100-1500 ºF - CA-40 1450-1650 ºF 1800-1850 ºF 600 ºF, max or 1100-1500 ºF - CA-6NM 1450-1500 ºF 1900-1950 ºF 600 ºF, max or 1100-1500 ºF - CA-6N 1900 ºF1 - 800 ºF2 air cool CB-30 1450 ºF, min - - air cool CB-7Cu-1 1925 ºF - 900-1150 ºF3 air cool CB-7Cu-2 1925 ºF - 900-1150 ºF3 air cool CC-50 1450 ºF, min - - air or furnace cool CD-4MCu 2050 ºF, min4 - - - CE-30 2000-2050 ºF - - water, oil or air CF-3 1900-2050 ºF - - water, oil or air CF-8 1900-2050 ºF - - water, oil or air CF-20 2000-2100 ºF - - water, oil or air CF-3M 1900-2050 ºF - - water, oil or air CF-8M 1950-2100 ºF - - water, oil or air CF-8C 1950-2050 ºF - - water, oil or air CF-16F 1950-2050 ºF - - water, oil or air CG-8M 1900-2050 ºF - - water, oil or air CH-20 2000-2100 ºF - - water, oil or air CK-20 2000-2150 ºF - - water, oil or air CN-7M 2050 ºF, min - - water, oil or air IN-862 2150 ºF - - water CW-12M 2200-2250 ºF - - water CY-40 - - - - Alloy 625 2150 ºF - - water Cz-100 - - - - M-35 - - - - N-12M 2100-2150 ºF - - water

1Reheat to 1500 ºF, air cool 2Aging Temperature 3Precipitation hardened Temperature Condition 900 ºF H 900 925 ºF H 925 1025 ºF H1025 1075 ºF H1075 1100 ºF H1100 1150 ºF H1150 *Held 3 hours, slowly cooled to 1400-1750 ºF, cooled in water, oil or air.

EFFECT OF CONSTITUENTS Nickel Chromium The addition of nickel supplements the passivating A chromium content of at least 11.5% is required to effect of chromium under oxidizing conditions and also provide surface passivity under oxidizing conditions and increases the resistance of the alloys to attack under to form an inert adherent surface film rich in chromium reducing conditions. Nickel in sufficient concentration oxide which is highly resistant to attack. A higher chro- results in a desirable austenitic structure and preserves mium content broadens the range of oxidizing condi- this structure through the many heat treatments to tions under which passivity is maintained. The chro- which castings may be subjected during production and mium content of corrosion-resistant castings ranges subsequent fabrication. In the higher nickel alloys, from 12 to 28% in the ACI alloys. nickel provides increased resistance to most reducing

29 environments. It also provides improved resistance to alloys were sparse, data on the wrought counterpart those chemical compounds to which nickel is particu- were included on the assumption that corrosion rates for larly resistant. These are typified by strong alkalies and both cast and wrought alloys would be similar. halogen compounds. In corrosion-resistant castings, the nickel content ranges from 1 to 96%. Pitting Corrosion Stainless steels are subject to localized loss of pas- Molybdenum sivity and subsequent pitting by the action of chloride Molybdenum has specific beneficial effects in improv- ions which penetrate the passive surface films. The ing resistance to sulfuric, phosphoric and hydrochloric incidence of such pitting is determined by the competi- acids. It also reduces the tendencies toward pitting in tion between the chloride ions which destroy passivity sea water and other chloride solutions. In the ACI alloys, and dissolved oxygen or other oxidizing substances the molybdenum content ranges from none to 30%. which passivate the surface. It is affected also by the composition of the alloy and the exposure conditions. Other Elements Favorable factors are the presence of molybdenum and Although chromium, nickel and molybdenum have a high nickel content represented, for example, by the the greatest influence on the properties of corrosion- 51% Ni-17% Mo-16.5% Cr compositions which is usu- resistant castings, other alloying elements also have ally resistant to pitting by chloride solutions even under their effects. adverse conditions. Favorable environmental factors are Carbon can have a detrimental effect on corrosion a plentiful supply of oxygen or other oxidizing agent or, resistance by combining with chromium to form a car- conversely, no oxygen at all, a high alkalinity and low bide. This undesirable effect can be eliminated by: temperature, a medium to high flow rate and freedom (a) Holding the carbon content below 0.03%. from deposits. The most unfavorable condition is repre- sented by exposure beneath deposits to a stagnant (b) Introducing columbium or titanium to form car- solution containing some dissolved oxygen. Turbulence bides of these elements instead of the harmful associated with high velocity flow is generally beneficial. chromium carbide. (c) Heating the alloy to a temperature sufficiently Sensitization high to dissolve the carbon and cooling rapidly When an austenitic stainless steel containing more enough to hold the carbon in solution. than 0.03% carbon, which is not stabilized by the pres- Columbium is added as a stabilizer to prevent precipi- ence of columbium or titanium, is heated in the 900- tation of chromium carbides. 1400 ºF range, chromium carbide will precipitate at the grain boundaries. The localized depletion of chromium Copper acts in the same manner as molybdenum to may make the alloy susceptible to intergranular attack in improve resistance to sulfuric and phosphoric acids. environments in which it ordinarily shows good Selenium in small quantities improves machinability resistance. Sensitization can usually be avoided by but it reduces corrosion resistance somewhat. keeping the carbon content at 0.03% or less, by adding Silicon also contributes to resistance to reducing small quantities of columbium or titanium, or by heating acids such as sulfuric, but impairs resistance to nitric to 2000 ºF for one hour per inch of thickness followed by acid. The silicon content of cast corrosion-resistant alloys quenching in water. is higher than that of the wrought alloys because this

element contributes the fluidity required to obtain satisfactory casting characteristics. However, silicon is a Magnetic Properties promoter of ferrite formation and, as a consequence, The Alloy Casting Institute grades containing up to tends to cause the formation of small amounts of ferrite in 4% nickel are all magnetic, as is the CE-30 grade. AIl the austenitic matrix. As one result, silicon increases the other grades fall within the austenitic alloy class, be- resistance of cast corrosion-resistant alloys to chloride cause of their compositions, and are substantially non- ion stress-corrosion cracking. magnetic. A small amount of magnetic ferrite is desir- able to facilitate weld repair although this ferrite may not CORROSIVE ATTACK be detected by a magnet. Occasionally, when the chro- mium is on the high side of the specification and the Corrosion is a complex phenomenon in which numer- nickel is on the low side, an unbalanced condition will ous variables influence not only the severity but also the develop in austenitic alloys that results in the formation type of attack. Therefore, it is not possible to make of a two-phase alloy composed of austenite and ferrite specific recommendations for alloy selection in a gen- The presence of ferrite in the structure will cause the eral publication. Certain limitations on the use of alloy to be slightly magnetic. This two-phase structure corrosion-resistant alloy castings and suggestions for will have corrosion resistance in practically all environ- counteracting them are discussed below. Table IX is ments equivalent to that of the single-phase austenitic included to serve as a guide in selecting candidate structure. An exception is in ammonium carbamate so- alloys for an environment. Where corrosion data on cast lutions such as are encountered in urea production.

30 ferrite present in austenitic stainless steel castings, in contrast with the single-phase austenitic structure of the Stress-Corrosion Cracking wrought alloys. The presence of ferrite in the castings is Under the combined effects of tensile stress and cor- desirable to facilitate weld repair but also increases rosion by specific environments (most commonly con- resistance to stress-corrosion cracking. There have centrated chlorides), certain stainless steel composi- been only a few stress-corrosion cracking failures with tions are subject to stress-corrosion cracking. Nickel cast stainless steels in comparison with the approxi- has the greatest effect on resistance to this form of mately equivalent wrought compositions. The principal attack. Resistance to such cracking is improved by in- reasons for this resistance are apparently (a) lower creasing the nickel content above the 8% level of the stresses, (b) silicon added for fluidity is also beneficial common CF-8 grade. from the standpoint of stress-corrosion cracking and (c) Although cast austenitic stainless steels are often sand castings are usually tumbled or sandblasted to considered to be similar to their wrought counterparts, remove molding sand and scale which probably tends to there is a difference. There is usually a small amount of put the surface in compression.

GROUPS OF CORROSION-RESISTANT ALLOY CASTINGS

The iron-base corrosion resistant alloys can be clas- parts, impulse wheels and pumps and valves for boiler sifed according to composition and metallurgical struc- feedwater service. ture into four broad groups: CA-6N (12Cr-7Ni) 1. Martensitic Alloys: CA-15, CA-40, CA-6NM, This is a higher nickel content modification of CA-15 CA-6N which has an excellent combination of strength, tough- 2. Ferritic and Duplex Alloys: CB-30, CC-50, ness and weldability. It has moderately good corrosion CD-4MCu resistance. 3. Austenitic Alloys: CE-30, CF types, CG-8M, CH-20, CK-20, CN-7M, CN-7MS, IN-862 4. Precipitation Hardenable Alloys: CB-7Cu-1, FERRITIC AND DUPLEX ALLOYS Cb-7Cu-2 CB-30 (20Cr-2Ni) In addition, nickel-base corrosion-resistant alloys in- Because of its higher chromium content, this alloy has clude nickel, high nickel-copper alloys, high nickel- better resistance to corrosion in many oxidizing environ- chromium alloys and other proprietary alloys. ments than the CA alloys. The addition of 2% nickel enhances corrosion resistance and increases tough- MARTENSITIC ALLOYS ness. It also has good abrasion resistance. Uses in- clude pump parts, turbine parts and valve trim. CA-15 (12Cr-1Ni) CC-50 (28Cr-4Ni) This alloy contains the minimum content required to attain surface passivity under oxidizing conditions. It Alloys containing about 28% chromium and up to 4% has good resistance to many mildly corrosive environ- nickel are resistant to a number of highly oxidizing me- ments that are oxidizing in character. It also has good dia such as hot nitric acid. They are also used in han- resistance to velocity effects in solutions for which it is dling corrosives such as acid mine waters which are suitable. The alloy is used widely for seats and discs in oxidizing and may be mildly abrasive. Among applica- valves in steam service and for parts of turbines ex- tions are cylinder liners, digester parts, pump casings posed to high velocity steam and impellers. CA-40 (12Cr-1Ni) CD-4MCu (26Cr-5Ni-3Cu-2Mo) This is the cutlery type of stainless steel which, by As cast, this alloy has a duplex ferrite and austenite virtue of its higher carbon content, can be hardened to a structure. Because of its low carbon content, there are only small amounts of chromium carbides distributed greater depth than type CA-15. It has good corrosion throughout the matrix, but for maximum corrosion resis- resistance to many environments, is tough and has tance, these carbides must be dissolved by suitable heat good resistance to abrasion. It is used for chipper treatment. Although the alloy can be precipitation blades, cutter blades, cylinder liners, grinding plugs, hardened, the ACI recommends that this alloy be used shredder sleeves and steam turbine parts. only in the solution annealed condition. It is highly resis- CA-6NM (12Cr-4Ni) tant to attack by some concentrations of sulfuric and hydrochloric acids and is exceptionally resistant to This is an iron-chromium-nickel-molybdenum alloy stress-corrosion cracking in chloride-containing solu- that is hardenable by heat treatment. In general corro- tions or vapors. It has also shown outstanding resis- sion resistance, it is similar to CA-15 and has been tance to such mixtures as nitric-adipic acid slurries and widely substituted for CA-15 because of easier process- wet process phosphoric acid slurries. Uses include ing through the foundry cleaning room. Among uses are compressor cylinders, pump impellers, digester valves compressor wheels, diaphragms, hydraulic turbine and feed screws.

31 AUSTENITIC ALLOYS and phosphoric acids and to certain hot organic acids CE-30 (29Cr-9Ni) such as formic, acetic and lactic acids. Molybdenum This alloy also is resistant to a number of highly also improves resistance to pitting in chloride salt solu- oxidizing corrosives and is particularly used for pumps, tions and sea water. valves and fittings handling sulfite liquors in the paper industry and some acid slurries in the metallurgical in- Grade CF-16F is similar to grades CF-8 and CF-20 dustries. Because of its high chromium content, the to which small amounts of selenium have been added to alloy can be made with a higher carbon content than the improve the machinability. The corrosion resistance of CF type alloy without suffering the injurious effects of this alloy is somewhat inferior to that of the CF-20 alloy carbide precipitation. For the same reason, it may be but is adequate for many purposes. used in place of the CF alloys where they must be welded without subsequent heat treatment. While often Controlled Ferrite Types used in the as-cast condition, ductility and corrosion The strength of the CF alloys cannot be improved by resistance of the CE alloy may be improved somewhat heat treatment but these alloys can be strengthened by by quenching from about 2000 ºF. Uses include digester increasing the ferrite phase at the expense of the aus- necks and fittings, circulating systems, fractionating tenite phase in these duplex microstructures. This fact towers, pump bodies and casings. has led to the introduction of controlled ferrite types, designated with an "A" suffix in some CF alloys, i.e., CF Alloys (19Cr-9Ni) CF-3A and CF-8A, for applications where higher The austenitic alloys containing about 19% chro- strength is desired than is obtainable in the CF-3 and mium, 9% nickel and less than 0.20% carbon constitute CF-8 types. Minimum tensile strengths for these con- by far the most widely used group of corrosion-resistant trolled ferrite types are 7 to 10 ksi higher than for the stainless alloys. These alloys are used for handling a regular types. The increased ferrite content generally wide variety of corrosive solutions in the chemical, tex- improves the resistance of the alloy to stress-corrosion tile, petroleum, pharmaceutical, food and numerous cracking in addition to increasing the strength. Because other process industries. In the chemical industry, they of the thermal instability of the higher ferrite microstruc- are particularly useful in handling oxidizing solutions ture, however, the controlled ferrite types are not con- such as nitric acid and peroxides and mixtures of acids sidered suitable for service at temperatures above such as sulfuric and phosphoric with oxidizing salts 650 ºF (CF-3A) or 800 ºF (CF-8A). such as ferric, cupric, mercuric and chromic salts. These stainless alloys are resistant to most organic CG-8M (19Cr-8Ni) acids and compounds as encountered in the food, dairy The high molybdenum content of this alloy (3-4%) and pharmaceutical industries. They also are resistant gives it improved resistance to hot sulfurous and or- to most waters including mine, river, boiler and tap ganic acids and to dilute sulfuric acid. It also has great waters. They are resistant to sea water under the high resistance to pitting. Uses include dyeing equipment, velocity conditions associated with pumping but are flow meter components, pump parts and propellers. subject to severe pitting attack in stagnant or slow mov- ing sea water. CH-20 (25Cr-12Ni) The limitation of the CF alloys is that most halogen With a carbon content of less than 0.20%, this alloy is acids and halogen acid salts tend to destroy their sur- similar in corrosion resistance to the CE-30 composi- face passivity. Thus, they are subject to considerable tion. It is used for specialized applications in the chemi- attack in such media as hydrochloric acid, acid chloride cal and paper industries. Uses include digester fittings, salts, wet chlorinated hydrocarbons, wet chlorine and roasting equipment, valves and pump parts. strong hypochlorites. For best resistance to corrosion, this alloy is produced CK-20 (25Cr-20Ni) in the low carbon CF-3 and CF-8 grades and should be This alloy is somewhat similar to the CE and CH types solution annealed to prevent intergranular attack in but has higher nickel content. It is sometimes made with a severely corrosive media. Heat treated CF-3 castings can columbium, or columbium plus tantalum addition, to be field welded or hot formed without subsequent re- minimize the effect of carbide precipitation. It is used in solution annealing, a major advantage in many appli- the pulp and paper industry to handle sulfite solutions. cations. Uses include digesters, filter press plates and frames, Columbium (niobium) or columbium plus tantalum mixing kettles and return bends. are sometimes added to produce carbide-stabilized CF- 8C alloy which, after heat treating, can be field welded or CN-7M (29Ni-20Cr) used at elevated temperatures without the precipitation of This designation covers a group of complex nickel chromium carbides and resultant susceptibility to chromium-copper-molybdenum alloys containing more intergranular attack of chromium depleted regions. nickel than chromium. The increased nickel content The addition of molybdenum as in grades CF-3M and together with the addition of copper and molybdenum CF-8M considerably increases the resistance of the give the alloy especially good resistance to sulfuric acid CF-alloys to such corrosive media as sulfuric, sulfurous and to many reducing chemicals. It has good resistance

32 to dilute hydrochloric acid and to hot chloride salt solu- resistant to oxidizing conditions. It is stronger and har- tions. The alloy also has excellent resistance to nitric der than nickel, and as tough. Industries in which it is and phosphoric acids. Uses include filter parts, heat used are: dairy, chemical, pharmaceutical, nuclear, pe- exchanger parts, mixer components, pickling hooks and troleum and food processing. Its corrosion resistance to racks, steam jets and ventilating fans; pumps and valves nitric acid, fatty acids, ammonium hydroxide solutions represent a major part of CN-7M applications. and oxidizing conditions in general is superior to nickel. This alloy is particularly useful in handling corrosive CN-7MS (24Ni-19Cr-3Mo-2Cu) vapors above 1470 ºF. The CN-7MS modification of CN-7M was developed for improved castability and weldability. Its corrosion Alloy 625 (60Ni-21Cr-9Mo) resistance is substantially equivalent to the CN-7M alloy. This high nickel-chromium-molybdenum alloy, like its wrought counterpart INCONEL* alloy 625, has excellent IN-862 (24Ni-21Cr-5Mo) corrosion resistance, especially in sea water, and is This alloy was developed as an alternative to CN-7M highly resistant to chloride stress-corrosion cracking. It for service in sea water. With its increased molybdenum has superior corrosion resistance in oxidizing atmos- content, it has better resistance to pitting and crevice pheres and to sulfur, and organic and inorganic com- corrosion than CN-7M but its corrosion resistance in pounds over a wide temperature range. Cast Alloy 625 sulfuric acid environments is lower. It has excellent has high levels of fatigue and creep strength, above casting and welding properties, thus giving it advan- those of CY-40. Sand-cast Alloy 625 can be air melted tages in production and repair compared with CN-7M. and poured, processed through the cleaning room in the as-cast condition, and can be welded using SMA PRECIPITATION HARDENABLE ALLOYS (coated electrode) or GMA (gas metal arc) processes without preheat or postweld heat treatments. CB-7Cu-1 (16Cr-4Ni-3Cu) This complex chromium-nickel-copper alloy can be CW-12M (55Ni-18Cr-18Mo) hardened by a precipitation heat treatment after solution annealing. It is not intended for use in the solution This complex nickel-chromium-molybdenum alloy annealed condition. The alloy can be used in service sometimes contains 5% tungsten and minor amounts of requiring corrosion resistance and high strength at tem- other elements. It has outstanding resistance to such peratures up to 600 ºF. In the precipitation hardened highly corrosive media as wet chlorine, strong hypo- condition, its corrosion resistance approaches that of the chlorite solutions, ferric chloride and cupric chloride and CF-8 alloy under certain conditions. is often applied in the handling of such chemicals. It also has good resistance to boiling concentrated or- CB-7Cu-2 (15Cr-5Ni-3Cu) ganic acids such as acetic, formic, lactic and fatty This complex chromium-nickel-copper alloy can be acids. Maximum corrosion resistance is obtained by quench- hardened by a precipitation hardening heat treatment ing the cast alloy from an annealing temperature of after solution annealing. It is not intended for use in the 2200-2250 ºF. solution annealed condition. It has a superior combina- tion of strength, toughness and weldability with moder- N-12M (63Ni-30Mo) ately good corrosion resistance. This alloy was developed particularly for resistance NICKEL-BASE ALLOYS to corrosion by hot concentrated hydrochloric acid solu- tions and wet hydrogen chloride. It is also resistant to CZ-100 (95Ni min) hot concentrated solutions of pure phosphoric acid and Cast nickel is outstanding for maintaining the purity of to hot dilute sulfuric acid. The alloy is most resistant a wide range of drugs, foods and chemicals. It is widely under reducing conditions and is not considered suitable used for the manufacture of caustics and for handling for handling oxidizing acids or solutions containing caustics in processes where low iron and copper content oxidizing salts. Maximum corrosion resistance is ob- in the equipment is important. tained by quenching the cast alloy from an annealing M-35 (63Ni-30Cu) temperature of 2100-2150 ºF.

This alloy shows good resistance to attack in reducing Nickel-Silicon Alloy (82Ni-10Si) environments. It is widely used in handling sulfuric, hydrochloric and organic acids in the marine, petro- This nickel-silicon alloy which sometimes also con- leum, chemical, power, sanitation, plastics, steel and tains 3% copper has exceptional resistance to all con- food processing industries. centrations of sulfuric acid up to the boiling point; conse- quently it is used in the concentration of sulfuric acid. It CY-40 (74Ni-15Cr) is also resistant to many other chemicals including phos- This nickel-base alloy has a superior combination of phoric, formic and acetic acids under reducing condi- corrosion resistance under a wide variety of conditions tions but is not resistant to strong oxidizing acids. Be- plus high levels of strength, ductility and weldability. It cause of its high hardness, this alloy is used extensively protects product purity much as nickel does, but is more to resist wear, abrasion and galling where corrosion may

*Trademark of the INCO family of companies 33 TABLE IX Corrosion Data

CF-3 CF-3M CD- Corrosive Medium CA-15 CA-40 CB-30 CC-50 CE-30 CF-8 CF-8M CF-8C CF-16F 4MCu CF-20 Acetic Acid 5% 4 4 3 3 1 2 2 1 2 2 10% 4 4 4 4 1 2 2 1 2 2 15% 4 4 4 4 1 2 2 1 2 2 20% 5 5 4 4 1 2 2 1 2 3 30% 5 5 5 5 1 2 2 1 2 3 40% 5 5 5 5 1 2 2 1 2 3 50% 5 5 5 5 1 3 3 1 3 3 60% 5 5 5 5 2 3 3 2 3 3 80% 5 5 5 5 2 3 3 2 3 3 99.9% 5 5 5 5 2 3 3 2 3 3 Acetic Anhydride 90% 5 5 5 5 2 3 3 2 3 3 Acetic Acid Vapors 30% 5 5 5 5 2 3 3 2 3 3 100% 5 5 5 5 3 4 4 3 4 4 Aluminum Acetate 4 4 4 4 1 2 2 1 2 2 Aluminum Chloride 5 5 5 5 4 5 5 5 5 5 Aluminum Hydroxide 4* 4* 4* 4* 3 4* 4* 3 4* 4* Aluminum Sulfate 5% 4 4 4 4 1 2 2 1 2 2 10% 5 5 5 5 1 3 3 1 3 3 Saturated 5 5 5 5 1 5 5 1 5 5 Alum (Aluminum Potassium Sulfate) 10% 5 5 5 5 1 3 3 1 3 3 Saturated 5 5 5 5 2 4 4 2 4 4 Ammonium Bicarbonate 3 3 2 2 1 1 1 1 1 2 Ammonium Carbonate 3 3 2 2 1 1 1 1 1 2 Ammonium Chloride 1% 2* 2* 2* 2* 1* 1* 1* 1 1* 1* 10% 3* 3* 3* 3* 2* 2* 2* 2* 2* 2* 20% 5 5 5 5 2* 4* 4* 3* 4* 4* 50% 5 5 5 5 3* 4* 4* 3* 4* 4* Ammonium Nitrate 2 2 2 2 1 1 1 1 1 1 Ammonium Sulfate 1% 3 3 3 3 1 1 1 1 1 1 5% 3 3 3 3 1 2 2 1 2 2 10% 4 4 4 4 1 2 2 1 2 2 Saturated 5 5 5 5 2 3 3 2 3 3 Bromine Liquid (Dry) 5 5 5 5 4 5 5 4 5 5 5 5 5 5 5 5 5 5 5 5 Bromine Liquid (H2O Saturated) Bromine Water (Dilute) 5 5 5 5 4 5 5 4 5 5 Calcium Chloride 5 5 5 5 4 5 5 5 5 5 Calcium Hypochlorite 5 5 5 5 5 5 5 5 5 5 Chlorine Gas (Moist) 5 5 5 5 5 5 5 5 5 5 Copper Sulfate 4 4 3 3 1 2 2 1 2 2 Ethylene Glycol 3 3 3 3 1 2 2 1 2 2 Fatty Acids 300 ºF 300 ºF 300 ºF 300 ºF 600 ºF 400 ºF 400 ºF 600 ºF 400 ºF 400 ºF Ferric Chloride 5 5 5 5 5 5 5 5 5 5 Ferric Sulfate 4 4 4 4 2 3 3 2 3 3 Ferrous Sulfate 4 4 4 4 1 2 2 1 2 2

LEGEND 1. Good resistance to boiling. 4. Good resistance to 70 ºF. 2. Good resistance to 160 ºF. 5. Not recommended. 3. Good resistance to 120 ºF. *Subject to pitting. **Dilute concentrations.

34 TABLE IX Corrosion Data

CF-3 CF-3M Corrosive Medium CA-15 CA-40 CB-30 CC-50 CD-4MCu CE-30 CF-8 CF-8M CF-8C CF-16F CF-20 Fluosilicic Acid 5 5 5 5 4 5 5 4 5 5 Formic Acid 5% 4 4 4 4 2 2 2 1 2 2 10% 4 4 4 4 2 2 2 1 2 2 50% 4 4 4 4 3 3 3 1 3 3 100% 5 5 5 5 3 3 3 2 3 3 Hydrochloric Acid 5 5 5 5 5 5 5 5 5 5 Hydrobromic Acid 5 5 5 5 5 5 5 5 5 5 Hydrofluoric Acid 5 5 5 5 5 5 5 5 5 5 Hydrogen Peroxide 3 3 3 3 2 2 2 2 2 2 Lactic Acid 5% 3 3 3 3 1 2 2 1 2 2 10% 5 5 5 5 2 3 3 2 3 3 100% 5 5 5 5 2 3 3 2 3 3 Magnesium Chloride 5 5 5 5 4* 5 5 5 5 5 Magnesium Sulfate 5 5 3 3 2 2 2 1 2 2 Nickel Chloride 5 5 5 5 4* 4* 4* 4* 4* 4* Nickel Nitrate 3 3 2 2 2 2 2 2 2 2 Nickel Sulfate 5 5 5 5 1 3 3 2 3 3 Nitric Acid 5% 3 3 2 2 1 1 1 1 1 1 20% 3 3 2 2 1 1 1 1 1 1 40% 4 4 3 3 1 1 1 1 1 1 50% 4 4 3 3 1 1 1 1 1 1 65% 4 4 3 3 1 2 2 3 2 2 100% 5 5 4 4 4 4 4 4 4 4 Oxalic Acid 5% 4 4 3 3 1 2 2 1 2 3 10% 5 5 4 4 2 3 3 2 3 3 25% 5 5 4 4 2 3 3 2 3 4 50% 5 5 5 5 2 4 4 3 4 5 Phosphoric Acid (Pure) 5% 3 3 3 3 1 1 1 1 1 1 10% 3 3 3 3 1 1 1 1 1 1 25% 5 5 4 4 1 2 2 1 2 2 50% 5 5 4 4 1 2 2 1 2 2 85% 5 5 4 4 2 3 3 2 3 3 Potassium Sulfate 4 4 3 3 1 3 3 2 3 3 Sodium Carbonate 4 4 3 3 1 2 2 1 2 2 Sodium Chloride 5 5 4* 4* 2* 3* 3* 2* 3* 3* Sodium Hydroxide < 20% 4 4 4 4 1 1 1 1 1 1 20-30% 4 4 4 4 2 2 2 2 2 2 30-50% 5 5 5 5 2 2 2 2 2 2 50-70% 5 5 5 5 5 5 5 5 5 5 70-80% 5 5 5 5 5 5 5 5 5 5 Sulfuric Acid 5-10% 5 5 5 5 2 4 4 3 4 4 10-20% 5 5 5 5 2 5 5 3 5 5 20-40% 5 5 5 5 3 5 5 5 5 5 40-60% 5 5 5 5 4 5 5 5 5 5 60-75% 5 5 5 5 4 5 5 5 5 5 75-85% 5 5 5 5 3 5 5 5 5 5 85-90% 5 5 5 5 2 4 4 3 4 4 90-100% 4 4 4 4 2 3 3 2 3 3 Zinc Chloride 5 5 5 5 3* 5 5 3* 5 5 Zinc Sulfate 5 5 5 5 1 4 4 2 4 4

(Continued on pages 36 and 37)

NOTE: It is not the purpose of this table to make specific recommendations. It should be used simply as a guide to indicate the most suitable candidate alloys. The effects of contamination, velocity, aeration, etc., will all tend to alter the rating of an alloy exposed to a corrosive environment.

35 TABLE IX Corrosion Data

Alloy Ni-Si Corrosive Medium CH-20 CK-20 CN-7M N-12M CW-12M 625 Alloy CZ-100 M-35 CY-40 Acetic Acid 5% 2 2 1 1 1 1 1 4 3 1 10% 2 2 1 1 1 1 1 3 3 1 15% 2 2 1 1 1 1 1 3 3 2 20% 2 2 1 1 1 1 1 3 3 2 30% 2 2 1 1 1 1 1 3 3 2 40% 2 2 1 1 1 1 1 3 3 2 50% 2 2 1 1 1 1 1 3 3 2 60% 3 3 1 1 1 1 1 3 3 2 80% 3 3 1 1 1 1 1 3 3 2 99.9% 3 3 1 1 1 1 1 3 3 2 Acetic Anhydride 90% 3 3 1 1 1 1 1 3 3 2 Acetic Acid Vapors 30% 3 3 1 1 1 1 1 3 3 2 100% 4 4 1 1 1 1 1 3 3 2 Aluminum Acetate 2 2 1 1 1 1 1 3 3 2 Aluminum Chloride 5 5 4 1 3 4 2 2 2 2 Aluminum Hydroxide 4* 4* 2 1 1 2 1 2 2 2 Aluminum Sulfate 59% 2 2 1 1 1 1 1 3 3 3 10% 3 2 1 1 1 1 1 3 3 3 Saturated 4 4 1 1 1 1 1 5 5 3 Alum (Aluminum Potassium Sulfate) 10% 3 2 1 1 1 1 1 3 3 3 Saturated 3 3 1 1 1 1 3 5 5 4 Ammonium Bicarbonate 1 1 1 1 1 1 1 2 2 2 Ammonium Carbonate 1 1 1 1 1 1 1 2 2 2 Ammonium Chloride 1% 1* 1* 1* 1 1 1* 1 1 1 1 10% 2* 2* 2* 1 1 1* 1 1 1 2* 20% 4* 4* 2* 2 1 1* 2 1 1 2 50% 4* 4* 2* 2 1 2* 2 1 1 2* Ammonium Nitrate 1 1 1 2 1 1 2 5 5 1 Ammonium Sulfate 1% 1 1 1 1 1 1 1 3 3 3 5% 2 2 1 1 1 1 1 3 3 3 10% 2 2 1 1 1 1 1 3 3 3 Saturated 3 3 1 1 1 1 1 3 3 3 Bromine Liquid (Dry) 5 5 3 3 2 3 3 1 1 1

Bromine Liquid (H2O Saturated) 5 5 4 3 2 3 3 3 3 3 Bromine Water (Dilute) 5 5 3 2 2 3 2 5 5 5 Calcium Chloride 5 5 4 3 1 3 3 2 2 2 Calcium Hypochlorite 5 5 5 5 3 4 5 5 5 5 Chlorine Gas (Moist) 5 5 4 3 1 4 3 5 5 5 Copper Sulfate 1 1 1 4 1 1 4 4 4 2

Ethylene Glycol 2 2 1 1 1 1 1 2 2 1 Fatty Acids 400 ºF 400 ºF 600 ºF+ 600 ºF+ 600 ºF+ 600 ºF 400 ºF 400 ºF 400 ºF 600 ºF Ferric Chloride 5 5 5 5 2 4 5 5 5 5 Ferric Sulfate 3 3 2 5 2 2 5 5 5 3 Ferrous Sulfate 2 2 1 2 1 1 2 3 3 3

LEGEND 1. Good resistance to boiling. 4. Good resistance to 70 ºF. 2. Good resistance to 160 ºF. 5. Not recommended. 3. Good resistance to 120 ºF. *Subject to pitting. **Dilute concentrations.

36 TABLE IX Corrosion Data

Alloy Ni-Si Corrosive Medium CH-20 CK-20 CN-7M N-12M CW-12M 625 Alloy CZ-100 M-35 CY-40

Fluosilicic Acid 5 5 3 3 2 2 3 4 1 4 Formic Acid 5% 2 2 1 2 1 1 2 2 1 2 10% 2 2 1 2 1 1 2 2 1 2 50% 3 3 1 3 1 1 3 2 1 2 100% 3 3 1 3 1 1 3 2 1 2 Hydrochloric Acid 5 5 5 2 3 4 5 3** 3** 4** Hydrobromic Acid 5 5 5 2 3 3 5 5** 5 5 Hydrofluoric Acid 5 5 4 4 3 4 4 4 1 4 Hydrogen Peroxide 2 2 2 5 3 3 5 3 4 2 Lactic Acid 5% 2 2 1 3 1 1 3 3 2 2 10% 3 3 1 4 1 1 4 3 2 2 100% 3 3 1 4 2 2 4 3 2 2 Magnesium Chloride 5 5 4* 1 1 1* 1 1 1 2* Magnesium Sulfate 2 2 1 1 1 1 1 2 2 2 Nickel Chloride 4* 4* 3* 1 2 3* 3 2 2 3* Nickel Nitrate 2 2 2 4 2 2 5 5 5 3 Nickel Sulfate 3 3 1 2 1 2 2 2* 2* 2 Nitric Acid 5% 1 1 1 5 1 2 5 5 5 3 20% 1 1 1 5 2 3 5 5 5 3 40% 1 1 1 5 3 3 5 5 5 3 50% 1 1 1 5 3 3 5 5 5 3 65% 2 2 2 5 4 4 5 5 5 3 100% 4 4 3 5 5 5 5 5 5 3 Oxalic Acid 5% 2 2 1 1 1 1 1 3 2 3 10% 3 3 1 1 1 1 3 3 2 3 25% 3 3 1 2 1 1 3 3 2 3 50% 4 4 1 3 1 1 4 3 2 3 Phosphoric Acid (Pure) 5% 1 1 1 1 1 1 1 4 1 3 10% 1 1 1 1 1 1 1 4 1 3 25°% 1 1 1 1 1 1 1 4 2 3 50% 2 2 1 1 1 1 1 4 2 3 85% 3 3 2 1 2 2 2 4 3 3 Potassium Sulfate 3 3 1 1 1 1 1 3 1 2 Sodium Carbonate 2 2 1 1 1 1 1 1 1 1 Sodium Chloride 3* 3* 1* 1 1 1 1 2 1 2* Sodium Hydroxide <20% 1 1 1 1 1 1 1 1 1 1 20-30% 2 2 1 1 1 1 1 1 1 1 30-50°% 2 2 1 1 1 1 1 1 1 1 50-70% 5 5 270 ºF4 4 2 1 1 1 1 70-80% 5 5 270 ºF4 4 2 1 1 1 1 Sulfuric Acid 5-10% 4 4 2 1 1 1 1 4 2 3 10-20% 5 5 2 1 1 2 1 4 2 3 20-40% 5 5 2 1 2 3 1 4 4 3 40-60% 5 5 3 1 2 4 1 5 4 4 60-75% 5 5 3 2 2 4 2 5 5 5 75-85% 5 5 3 2 2 4 2 5 5 5 85-90% 4 4 2 2 2 3 2 5 5 3 90-100% 3 3 225 ºF 250 ºF 2 2 2 4 4 3 Zinc Chloride 5 5 2* 1 2* 2* 1 2 1 2* Zinc Sulfate 4 4 1 1 1 1 1 2 1 3

NOTE: It s not the purpose of this table to make specific recommendations. It should be used simply as a guide to indicate the most suitable candidate alloys The effects of contamination, velocity, aeration, etc., will all tend to alter the rating of an alloy exposed to a corrosive environment.

37 Industrial Applications of Corrosion-Resistant Alloy Castings

AERONAUTICAL Although the greatest use for high alloys in this industry Typical Applications is for engine parts required to withstand high temperatures, Fuel jets there are applications for the corrosion-resistant grades in Fuel valves Engine supports components that must resist both corrosive and erosive effects to insure dependable operation.

BALL VALVE CONTROL VALVE Alloy: CF-8 (19Cr-9Ni) Alloy: CB-30 modified Use: Cryogenic ball valve for service on advanced rocket engine. Use: Aircraft fuel control valve subject to high rate fuel impingement on 2000 mph aircraft.

ARCHITECTURAL The cast chromium-nickel alloys are used as ornaments and other components in the architectural treatment of Typical Applications buildings, bridges, etc. Where these will be exposed to a Ornaments Fire wall fittings marine environment, the molybdenum-containing austenitic Hand rail fittings Grilles

grades have the most satisfactory resistance to corrosion.

38 CHEMICAL AND PETROLEUM Chemical The corrosion-resistant alloys have their widest application in the chemical industry. Their function is two-fold: they pro- vide good equipment life and prevent product contamination. Many chemical operations would not be economically feasible if it were not for the corrosion and abrasion-resistant properties of these alloys.

Typical Applications Grinders Nozzles Mixers Vessels Pumps Piping and fittings Valves Conveyors

Petroleum Cast corrosion-resistant alloys of all types are used exten- sively in the petroleum industry to withstand the corrosive effects of moist sulfur and carbon dioxide-bearing gases, sour crudes, sulfuric acid and caustic treating equipment, phos- phoric acid, salt water and the many forms of organic acids produced as by-products during the refining operations.

Typical Applications CENTRIFUGAL PUMP CASING AND COVER Alloy: CF-8M (19Cr-9Ni-2Mo) Valves Pipe fittings Weight: 4000 Ib each pump Pumps Nozzles Use: Pump to circulate 5500 gpm of highly corrosive chemicals with low Heater tubes specific gravity.

CENTRIFUGALLY-CAST FLANGE Alloy: CH-20 modified with free ferrite controlled at 5-15% (25Cr-12Ni) Weight: 150 Ib Size: 4 in. 2500 Ib welding neck flange @ 14 in. flange O.D. x 3 in. thick x 4½ in. neck O.D. x 7¾ in. O.A.L. Use: Hydrocracker refinery unit

PRESSURE VESSEL Alloy: CK-20 (25Cr-20Ni) Weight: 8,900 Ib Use: Dissolver vessel in chemical processing plant.

PROCESS PIPING Alloy: CF-3M (19Cr-10Ni-2Mo) Weight: 1400 Ib Size: 16 in. O.D. x ¾ in. wall; flange 26 in. O.D. Use: Acetic acid processing

39 BUTTERFLY VALVE-AUTOMATIC, ON-OFF Alloy: CF-8M (19Cr-9Ni-2Mo) BUTTERFLY VALVE–AUTOMATIC CONTROL Weight: Body and disc 300 Ib Alloy: CF-8M (19Cr-9Ni-2Mo) Size: 12 in. Weight: 600 Ib Use: Chemical service Size: 24 in. Use: Chemical service

PUMP COMPONENTS Alloy: CF-8 (19Cr-9Ni) and CF-8M (19Cr-9Ni-2Mo) Parts: Housings, gears, impellers Use: Pumps in a variety of applications primarily in the Chemical Processing Industry. All parts are investment castings

PUMP Alloy: CG-8M (Modified)–wetted parts Size: 16 in. Use: Flash cooler service in phosphoric acid plant.

GATE VALVE Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: Body casting, 1603 lb; bonnet casting, 414 Ib Use: Wedge gate valve for chemical plant service.

40 PROCESS INDUSTRIES EQUIPMENT Food Processing Metal Mining and Refining The corrosion-resistant stainless steels are widely used in The austenitic stainless steels have good resistance all types of food handling equipment. Their good resistance to to all mine waters which contain sulfur compounds. The both corrosion and abrasion avoids the hazard of contamina- CF-8M alloy is usually reliable for most of these tion with metal compounds that might be toxic or might lead to conditions. food spoilage. In the sulfuric acid leaching of copper ores, the CN-7M alloy is used in pumps and valves required to handle the 66° Bé sulfuric acid solution. The copper-containing solution accumu- Typical Applications lated after leaching is resisted satisfactorily by the CF-8M Mixers Nozzles alloy. Grinders Disintegrators Valves Screw spindles The CN-7M alloy is also widely used in the sulfuric acid Pumps Screens treatment of phosphate ore for the production of phosphoric Agitators acid.

Typical Applications

Valves Pipe fittings Pumps Filters

Pharmaceutical The CF alloys (19Cr-9Ni) are widely used in the pharma- ceutical industry and in the fine chemical industry in corrosive Typical Applications as well as in relatively non-corrosive environments for main- taining purity and color of the products. Stainless steels are Pumps Agitators Valves Nozzles used in processing Vitamin C, acid solutions containing chlo- roform, ammonium sulfate, sodium sulfite and to resist organic acids from protein extraction and biological mediums.

Plating Pulp and Paper The austenitic stainless steels are used in the electroplating The severely corrosive conditions developed in both industry for equipment to handle alkaline cyanide copper plating the sulfite and the sulfate treating of wood require use of baths, sulfuric acid copper plating baths and some chromic acid corrosion-resistant alloys for good service life and to plating baths. They are employed in pumps and valves in avoid contamination by corrosion products. In the sulfite equipment used for the storage and handling of 66° Bé sulfuric process, alloys having good resistance to acid acid. The stainless steels are not suitable for handling nickel environments are required while in the sulfate process chloride and other type plating baths. Tests should be con- alloys are required that have good resistance to caustic ducted in solutions of this type to determine the suitability of environments. Frequently, an alloy will be found that has alloys such as N-12M and CW-12M. satisfactory resistance to conditions encountered in both The austenitic stainless steels are used in equipment for operations. handling the nitric-phosphoric bright-dip solution for alumi- Many of the corrosion-resistant alloys have excellent num. resistance to erosive effects. This property is exploited in early grinding steps as well as in subsequent steps employed in processing the wood pulp. Typical Applications

Valves Filters Typical Applications Pumps Fittings Grinders Black liquor equipment Digester blow valves Causticizing equipment Stock line valves Bleaching equipment Stock lines and fittings Sulfuric and sulfurous acid White liquor equipment equipment Green liquor equipment Chlorine dioxide Sulfur dioxide

41 CENTRIFUGAL PUMP Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: Upper half 1175 lb; lower half 3000 lb 5 Size: 57½ in high x 64 /8 in. wide x 58½ in. deep Use: Pump for handling 14,800 gpm of caustic, corrosive paper stock ("white water").

CENTRIFUGE BOWL Alloy: CG-8M (19Cr-10Ni-3Mo) Weight: 1679 Ib Size: 28 in. O.D., 78 in. long Use: Centrifuges in municipal sewage treatment plant.

VERTICAL PUMP Alloy: CF-8M (19Cr-9Ni-2Mo)–wetted parts Size: 24 in. TURBINE PUMP Use: Liquid end of pump handling 20,000 gpm acid contaminated water. Alloy: CF-8M (19Cr-9Ni 2Mo) –wetted parts Use: Dewatering service in gold mine.

42 DIGESTER SCREENS–PIPE FITTINGS Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: various–screen segments 100 Ib each Size: 6 in. pipe size at digester fitting Use: Screens separate pulp from liquor inside digester. Complex fittings used at bottom of digester between it and blow pit. Liquor is ammonium sulfite (acid base).

PUMP Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: 450 Ib Size: 6 in. x 8 in.–1800 rpm Use: Sulfuric acid leaching of copper silicate ores at ambient temperature. Sulfuric acid strength 1-2%.

SINGLE-STAGE CENTRIFUGAL PUMP Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: 450 Ib SUCTION ROLL SHELLS Size: 8 in. x 10 in.–1800 rpm (Suspended Castings) (Casting being bored) Use: Pumping silicate-sulfuric acid liquor in copper leaching Alloy: CA-15 (12Cr) Alloy: CF-8M (19Cr-10Ni-2Mo) operation. Weight: 97,200 lb Weight: 64,600 lb Use: Both used in wet end of paper machine to resist corrosion by white water while aiding in drying paper.

43 CENTRIFUGAL PUMP SINGLE STAGE CENTRIFUGAL PUMP Alloy: CF-8M (Modified) Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: Top casing, 1600 lb; lowercasing, 2380 lb Weight: 600 lb Use: Handling acidic river water in steel plant–after 22 years, pump Size: 6 in. x 8 in–1800 rpm showed no sign of corrosion. Use: Stock pump in pulp mill based on ammonium sulfite process– acid-base sulfite liquor is present.

MARINE Although CF-type alloy castings have to be used selectively in the marine field because of their susceptibility to pitting corrosion, they have applications where, because of velocity conditions, this form of deterioration cannot develop. The chromium-nickel type (CF-8) steels have been used successfully for propellers on tugs and other types of work-boats that are in relatively constant service. The CF-3M, CF-8M and CN-7M alloys are frequently used for components in salt water pumps and valves. These alloys have also been used successfully in equipment which is exposed to a marine atmosphere.

Typical Applications

Ship propellers Salt water valves Salt water pumps Some marine hardware

PROPELLER Alloy: CF-3 (19Cr-9Ni) Weight: 22,660 Ib Size: 15 ft O.D. Use: Workboat

44 POWER–NUCLEAR AND CONVENTIONAL Nuclear Energy In this field, heat and corrosion-resistant alloys are used in both statically and centrifugally cast forms. Rigid specifications may require tensile property tests, hydrostatic tests, radiographic and dye penetrant examina- tions, depending upon the particular application.

Typical Applications Valves Control mechanisms Pump impellers Reactor components CENTRIFUGALLY-CAST PIPE Pump casings Alloy: CF-8A (19Cr-9Ni) Weight: 11,500 Ib (front piece) Size: 32 in. O.D., 184 in. long (front piece) Use: Nuclear reactor coolant loop pipe for pressurized water Power Plants reactor. Meets requirements of ASME Sec. III. The use of chromium-nickel stainless steels for compo- nents in power plant equipment has increased the ability of this industry to meet the ever increasing demand for more industrial power. These alloys have made it possible for power plant engineers to design equipment for operation at increased pressures and temperatures. In nuclear power plants, the chromium-nickel stainless steels are used to avoid contamination of the coolants by metallic corrosion products that would become radioactive.

Typical Applications

Feed water heating equipment Boiler water deaerator heaters Valve components (feed water, steam, condensate, fuel oil) Pump components (feed water, condensate, fuel oil)

CENTRIFUGALLY-CAST TUBE Alloy: CF-8 (19Cr-9Ni) Hydraulics Weight: 410 Ib Size: 8.2 in. O.D. x 5 in. I.D. x 56 in. long In the hydraulics field, the good resistance to Use: Nuclear control rod drive latch housing. abrasion and cavitation of the chromium-nickel alloys is of more significance than their corrosion resistance. This property makes it possible to design smaller diameter equipment that will convey large volumes at higher velocity than it would be possible with other alloys that do not have this inherent characteristic. CENTRIFUGALLY-CAST FLANGES Alloy: CF-8M with controlled ferrite (19Cr-10Ni-2Mo) Weight: 1500 Ib Typical Applications Size: up to 24 in. pipe size Use: Nuclear piping flowmeter flanges Pumps Nozzles Valves Piping and fittings Torque tubes

45

VALVE BODY AND BONNET CASTINGS Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: Body casting, 1565 lb; bonnet casting, 740 Ib Use: Castings meet Nuclear Class II, used in valves for nuclear power plant.

BUTTERFLY VALVE BODIES Alloy: CF-8M (19Cr-10Ni-2Mo) Weight: 300 Ib Size: 16 in. Use: Nuclear service–must meet ASME Class II requirements.

FRANCIS TYPE RUNNER Alloy: CF-20 (19Cr-9Ni) Weight: Range from 460 to 3030 Ib Size: 325/8 in. dia Use: For hydraulic turbine installations in the power industry.

CENTRIFUGALLY-CAST BEARINGS Alloy: CF-3A (19Cr-9Ni) Weight: 800-900 Ib Size: 331/2 in. flange O.D. x 28 in. barrel O.D. x 255/8 in. I.D. x 17 in. long Use: Hydrostatic bearings for nuclear recirculating pumps.

46

FLOWMETER NOZZLES Alloy: CF-8M with controlled ferrite (19Cr-10Ni-2Mo) Weight: 975 Ib Size: 243/8 in. flange x 16 in. barrel O.D. x 1¼ in. wall x 341/8 in. long Use: Venturi-style flowmeter bodies for use inside main water recirculating in nuclear power plants.

CONTROL VALVE, AUTOMATIC CONTROL Alloy: CF-8 (19Cr-9Ni) Weight: 250 Ib Size: 6 in. pipe size Use: Nuclear service, light water reactor, PWR primary loop, by-pass. CHECK VALVE Alloy: CF-8 (19Cr-9Ni) Weight: 450 Ib Size: 6 in. pipe size Use: Nuclear water service handling demineralized water in the primary loop of a pressurized light water reactor.

STEAM TURBINE CASING Alloy: CK-20 (25Cr-20Ni) Weight: 9000 Ib Use: High temperature, high pressure steam service.

47 BUTTERFLY VALVE DISC Alloy: CF-3M (19Cr-9Ni-2Mo) Weight 160 lb Size: 20 in. dia BAILEY CONTROL VALVE Use: Control valve handling raw fresh water from California project to filtering Alloy: CF-3M (19Cr-9Ni-2Mo) Weight: 5200lb plant. Size: 32 in. dia (port size) Use: Potable water service, Metropolitan Water District of Southern California.

MULTISTAGE WATERFLOOD PUMP CASING Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: 4200 lb Size: 4 in. x 6 in -3600 rpm Use: Waterflood Huntington Beach, California. Aminol-treated sea water, de-aerated, inhibited, biocides added.

CENTRIFUGAL PUMP IMPELLER Alloy: CF-8M (19Cr-9Ni-2Mo) Height: 36,000 lb Size: 144 in. dia Use: Handling freshwater containing silt, on Central Valley California water project. Replaced bronze which suffered cavitation and erosion corrosion.

HORIZONTALLY SPLIT, 5 STAGE, HIGH PRESSURE PUMP Alloy: CF-8M (19Cr-9Ni-2Mo) Weight: 1050 Ib (part shown) Size: 4 in. x 6 in. -3600, rpm Use: Treated sea water–oil field water flood service.

48 Part III Fabrication Data For Heat and Corrosion-Resistant Alloys

Casting is a fabricating step and by its nature is the High speed steel and cemented carbide tools are quickest method of converting an alloy into a nearly used for machining the high alloy castings. Cutting finished product. The elimination of intermediate steps speeds and feeds for high speed steel tools are shown between the molten metal stage and the shaped part in Table X for heat-resistant alloys and in Table XI for provides important economic advantages to the casting corrosion-resistant alloys. With carbide tools, about two process. to three times these speeds should be used. The tool Many castings can be used directly after cleaning and should not be permitted to dwell in the cut as work cutting off the gates and risers but some require machin- hardening of the material will result. Machines should be ing to finished dimensions or welding into assemblies. powerful and rigid and tool mountings stiff. This section presents information on the machining and Cutting lubricants are essential for all machining op- welding practices used on heat and corrosion-resistant erations on these castings. For best results, a continu- castings. ous and abundant supply of cutting fluid should be fed to the tool and thereby act also as a coolant. All lubricants MACHINING should be removed completely from the machined parts High-alloy castings are more difficult to machine than that are to be subjected to high temperatures, either carbon steel because of the characteristics built into during subsequent fabrication or in service. For high them for heat and corrosion-resistant service. With speed steel tools, sulfurized cutting oils are the pre- proper tools and coolants, however, all necessary ma- ferred cutting lubricants. A lubricant of soluble oil and chining can be performed under conditions of compara- water is used with cemented carbide tools. tively slow speeds and moderate feeds. Single point tool grind angles for high speed steel are shown in Figure 6. TABLE X Machining and Welding of Heat-Resistant Alloy Castings

HA HC HD HE HF HH HI HK HL HN HP HT HU HW HX MACHINING Rough Turn Speed, sfm 40-50 40-50 40-50 30-40 25-35 25-35 25-35 25-35 30-40 35-45 35-45 40-45 40-45 40-45 40-45 Feed, ipr .010-.030 .025-.035 .025-.035 .020-.025 .015-.020 .015-.020 .015-.020 .020-.025 .020-.025 .020-.025 .020-.025 .025-.035 .025-.035 .025-.035 .025-.035 Finish Turning Speed, sfm 80-100 80-100 80-100 60-80 50-70 50-70 50-70 50-70 60-80 70-90 70-90 80-90 80-90 80-90 80-90 Feed, ipr .005-.010 .010-.015 .010-.015 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .010-.015 .010-.015 .010-.015 Drilling Speed, sfm 35-70 40-60 40-60 30-60 20-40 20-40 20-40 20-40 30-60 40-60 40-60 40-60 40-60 40-60 40-60 Feed, ipr 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Tapping Speed, sfm 10-25 10-25 10-25 10-25 10-20 10-20 10-20 10-20 10-25 5-15 5-15 5-15 5-15 5-15 5-15 Remarks 15 17 15 17 15 17 17 16 17 16 17 16 17 16 17 17 16 17 – 16 17 16 17 16 17 16 17

WELDING E505-18 E446-15 E446-15 E312-15 E308-15 E309-15 E310-15HC E310-15 E310-15HC E330-15 E310-15 E330-15 E330-15 ENiCr-1 or ENiCrFe-1 Electrode Type (also 18Cr- ENiCrFe- 38Ni Bare) 1

Oxy-acetylene Rod Type 410 Bare 446 Bare 327 Bare 312 Bare 308 Bare 309 Bare 309 Bare 310 Bare 310 Bare 330 Bare – 330 Bare 330 Bare Inconel Inconel Oxy-acetylene Flux None None None None None None None None None None – None None StainlessStainless Oxy-acetylene Flame – – – – – S S M M – V V – – Character1 Preheat and Interpass 450-550 60-100 Not. Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Temperature, F Post Heat Treatment, F 2 1550 A. C. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Annealing Treatment, F 16255 As-Cast As-Cast As-Cast As-Cast3 As-Cast4 As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast4 As-Cast4 As-Cast As-Cast

Notes for Table X with Table XI on page 50.

49 TABLE XI Machining and Welding of Corrosion-Resistant Alloy Castings

CA- CD- CA-15 CA-40 6NM CB-30 CC-50 4MCu CE-30 CF-3 CF-8 CF-20 CF-3M CF-8M CF-8C CF-16F CG-8M CH-20 CK-20 CN-7M

MACHINING Rough Turn Speed, sfm 40-50 25-35 40-50 40-50 40-50 40-50 30-40 25-35 25-35 25-35 25-35 25-35 30-40 45-55 25-35 25-35 25-35 45-55 Feed, ipr 010-.030 .030-.040 .010-.030 .020-.030 .025-.035 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 Finish Turning Speed, sfm 80-100 50-70 80-100 80-100 80-100 80-100 60-80 50-70 50-70 50-70 50-70 50-70 60-80 90-110 50-70 50-70 50-70 90-110 Feed, ipr .003-.010 .015-.020 .005-.010 .010-.015 .010-.015 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 Drilling Speed, sfm 35-70 30-60 20-50 30-60 40-60 20-40 30-60 20-40 20-40 20-40 20-50 20-50 30-60 30-80 20-50 20-50 20-40 30-60 Feed, ipr 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Tapping Speed, sfm 10-25 10-20 10-20 10-25 10-25 10-20 10-25 10-20 10-20 10-20 10-20 10-20 10-25 15-30 10-20 10-20 10-20 10-25 Remarks 12 13 – 14 14 – 15 15 15 15 15 15 15 – 15 15 15 –

WELDING Electrode Type E410-15 E410-15 – E442-15 E446-15 – E312-15 E308L-15 E308-15 E308-15 E316L-15 E316-15 E347-15 E308-15 E317-15 E309-15 E310-5 E320-15 Oxy-acetylene 410 Bare 420 Bare – – – – – – – – – – – – – – – – Rod Type Preheat and Interpass Temperature, ºF 400-600 400-600 500-600 600-800 350-400 Not. Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. 400-500 Post Heat 1125- 1125- 1100- 1450- 1650 A. C. 2050 1950- Not Req. 1950- 2000- Not Req. 1950- 1950- 2000- 1950- 2000- 2WQ- 1950 7 7 7 7 7 7 7 7 7 Treatment, ºF 1400 A.C. 1400 A.C. 1150 A.C. 1500 A.C. 2050 2050 2100 2100 2050 2100 2050 2100 2150 2050 2050 F.C. 9 9 9 9 9 9 – 9 9 9 Annealing 1450- 1550- 1550- 1450- 1450- to 1750- 1950- 1950- Treatment, ºF 1500 F.C. 1650 F.C. 1650 F.C. 1500 F.C. 1500 F.C. 1900 2050 2150 8 or A.C. A.C. Heat Treatment for Increasing Strength – – – 11 11 – 11 11 11 11 11 11 11 11 11 11 11 11 Hardening Temp., ºF 1800- 1800- 1900- – – – – – – – – – – – – – – – 1850 1850 1950 Quenching Medium oil oil oil – – – – – – – – – – – – – – – or air or air or air Tempering Temp., ºF 600 max 600 max 600 max – – – – – – – – – – – – – – – 10 10 10

Notes for Tables X and XI 1V – very rich in acetylene; excess acetylene feather should project 1" beyond tip of inner core. M – medium rich in acetylene; excess acetylene feather should project ½" beyond tip of inner core. S – slightly rich in acetylene; excess acetylene feather should project ¼" beyond tip of inner core. 2 Heat to original draw temperature, hold sufficiently long to insure uniform heating throughout section, then air cool. 3 When castings are repeatedly heated and cooled in service, properties may be improved by heating at 1900 ºF for six hours, then furnace cooling. 4 When castings are repeatedly heated and cooled in service, properties may be improved by heating at 1900 ºF for twelve hours, then furnace cooling. 5 For improved strength, castings are normalized by heating to 1825 ºF, air cooling to below 1300 ºF, followed by tempering at 1250 ºF. 6 Drilling feeds: Drill Diameter Feed, ipr Under 1/ 8 “ 001-.002 1/ 8 - ¼ 002-.004 ¼ - ½ .004-.007 ½ - 1 .007-.015 Over 1 015-.025

7 This post-weld heat treatment is to restore maximum corrosion resistance. Quench should be in water, oil or air according to section size, geometry and cooling rate that will hold as great a portion of the carbides in solution as possible. 8 Furnace cool to 1000 ºF, then air cool. 9 Same as post-heat treatment. 10 Avoid tempering around 900 ºF. Lower strengths than obtained with 600 ºF max temper may be achieved by tempering in 1100-1500 ºF range. 11 This alloy normally supplied in the annealed condition. 12 Cuts best when hardened to 225 Brinell. 13 Chips are stringy. 14 Chips are short and brittle. 15 Use chip curler. 16 Use chip curler and breakers. 17 Chips are tough and stringy.

Not Req. –usually not required. A.C. –air cool F.C. –furnace cool

50 A. Arc Welding – The electrical resistance of nickel- chromium and chromium-nickel castings is about six times that of carbon steel, and the melting point of the alloys is approximately 100 ºF lower. This combination of greater resistance and lower melting point permits these alloys to be arc welded using lower currents than those required for welding carbon steels. Particular care must be exercised with the corrosion-resistant types to have the welding groove well cleaned and free of grease or dirt, for any contamination of the weld might result in carbon pick-up. When welding heat-resistant alloys of the nickel-chromium group, the work must be kept clean of lubricants and marking crayons that contain sulfur or lead; otherwise cracking may result. Weaving of the bead should be avoided because a large puddle pro- Figure 6–Tool Bit Angles for High Speed Steel Tools for Machining motes weld cracking unless bead width is limited to 3 Stainless Steel Castings. times the electrode diameter. Welding Current – Reverse polarity D.C. is most WELDING commonly used for welding the nickel-chromium and All of the common welding methods can be used on chromium-nickel alloys. Table XII lists suggested elec- high-alloy castings. Information on pre-heat and post- trical settings and electrode sizes for these alloys of heat treatments are given for the heat-resistant alloys in different thicknesses. (In general, these alloys require Table X and for corrosion-resistant alloys in Table XI. about 10% less current than the carbon steels.) The metal-arc process is used in most cases, especially Electrode Selection – The electrode selected to weld a for the corrosion-resistant alloys, while oxy-acetylene corrosion-resistant cast alloy should deposit the same welding is usually limited to the heat-resistant types. alloy content as the casting. To accomplish this, the Oxy-acetylene welding is not normally used for electrode core and coating are adjusted to compensate corrosion-resistant castings because carbon pick-up is for melting losses that occur during welding. Particular possible if the flame is not correctly adjusted. Carbon care should be exercised with the corrosion-resistant pick-up would decrease the corrosion-resistance of the cast alloys of low carbon content to assure that the chromium-nickel alloys. In the relatively tougher heat- electrode does not add more carbon. resistant alloys, this limitation does not exist and oxy- acetylene welding can be employed. Inert-gas welding For the heat-resistant alloys, welding electrodes ca- with tungsten or consumable electrodes is common in pable of depositing high carbon weld metal help prevent the repair welding of investment castings. Submerged cracking. The varying levels of silicon present in the arc welding is confined mainly to fabrication of several heat-resisting alloy compositions, sometimes corrosion-resistant alloys. Flash welding is utilized in require an adjustment of the carbon introduced into the special applications, such as the joining of tubular weld deposit by the electrode. This is done by the elec- sections. trode manufacturer to maintain the proper carbon- silicon ratio in the weld deposit and thus eliminate crack- 1. Welding Nickel-Chromium and Chromium-Nickel ing. Groups of Both Heat and Corrosion-Resistant Grades. Lime coated electrodes are usually preferred for welding high-alloy castings. All welding slag must be Alloy castings of the nickel-chromium-iron and removed after welding, for when service temperatures chromium-nickel-iron groups can be welded satisfacto- approach the melting point of the slag, severe metal rily and the resultant joints will have the same mechani- attack can occur. cal and physical properties as the base metal. These alloys have better weldability than the straight chro- B. Oxy-Acetylene Welding–Oxy-acetylene welding mium alloys. Preheating is seldom required, but post- may be used on the heat-resistant types but this type of weld heat treatments are employed with the corrosion- welding should not be used on chromium-nickel cast- resistant types to restore uniform corrosion resistance. ings intended for corrosion-resistant service. For the The thermal conductivity of these alloys is about one- heat-resistant grades, a carburizing flame rich in acety- third that of carbon steel and the thermal expansion lene is suggested, especially if service conditions coefficient is about 50% greater. This low conductivity include a carburizing atmosphere. results in the retention of local heat for longer times and 2. Welding the Straight Chromium Alloys the high coefficient of expansion means that higher residual stresses and more distortion can be anticipa- The straight chromium alloys are divided into harden- ted. able and non-hardenable groups.

51

The virtue of the hardenable alloys is that their use carbon steel because of their greater electrical resis- permits refinement of the grain size, and also the devel- tance and lower melting points. opent of a variety of mechanical properties by suitable Welding Current – Reverse polarity direct current is heat treating procedures. This hardenability, however, most commonly used in welding straight chromium necessitates extra care when welding, for it can result in alloys; however, AC can be employed. The type of brittle structures in the weld deposits and heat-affected welding current used, whether direct or alternating, is a zone if the weld casting is allowed to cool down to room function of the flux casting present on the electrode. temperature in air. Heat treatment is necessary to re- Table XIII shows suggested electrical settings and elec- store ductility and must be done immediately following trode sizes for the various section thicknesses. welding, and care must be taken that the castings re- ceive no rough handling between welding and heat Electrode Selection – In selecting the proper elec- treating. Cracking and distortion can be minimized by trode, it is important that the weld metal have the same welding the castings only after annealing and not in the corrosion and heat-resistant properties as the parent as-cast condition. metal. The composition of the casting and commercial electrodes are not exactly the same, for the electrode is The non-hardenable straight chromium alloys contain generally made to an AWS specification as listed it 18 to 30% Cr, and, although they do not harden when Tables X and XI. cooled rapidly, grain growth and brittleness result. Gen- erally speaking, these grades have limited weldability Lime coated electrodes are generally used for weld- and call for extreme care in welding and in composition ing the straight chromium alloys, for they are considered control (i.e., nickel content should be kept near the to give cleaner weld metal and allow for better bead maximum allowable in the specification). build-up than the titania or titania lime-coated rod. A. Arc Welding – In arc welding straight chromium B. Oxy-Acetylene Welding – Gas welding does not heat and corrosion-resistant castings, the welding cur- find wide application for the straight chromium alloys rents used are qenerally lower than those employed for and is limited to those with less than 14% chromium.

TABLE XII TABLE XIII Electrical Settings and Electrode Size for Welding Electrical Settings and Electrode Size for Welding Chromium-Nickel Alloy Castings Straight Chromium Alloy Castings

Casting Arc Volts, Casting Thickness Electrode Amperes max Thickness Electrode Amperes Volts at Weld, Diameter, at Weld. Diameter, in. In. in in

Under 1/16 1/16 25-40 22 Under 1/16 5/64 25-40 20-22 5/64 35-55 23 1/16-9/64 3/32 or 1/8 50-90 22-24 1/16-7/64 3/32 45-70 24 9/64-3/16 1/8 or 5/32 90-125 22-24 7/64-3/16 1/8 70-105 25 3/16- 1/2 5/64 or 3/16 100-150 23-27 3/16-1/2 5/32 100-140 25 1/2 and above 3/16 125-175 26-29 1/2 and above 3/16 130-180 26

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