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© 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

Chapter 1

Superalloys for High Temperatures—a Primer

How and When to Use This Chapter in the field, check the table of contents and index for valuable insights into what you can It is always difficult to locate concise but find in each succeeding chapter. precise information on a subject. Executives and managers, particularly in industries using few superalloys, often need just basic infor- Some History mation with the least extraneous or amplify- ing data. Purchasing agents or communica- Designers have long had a need for tions experts need a modest knowledge base stronger, more -resistant materials to do their jobs more appropriately. The en- for high-temperature applications. The stain- gineer may need more detail but still just a less , developed and applied in the sec- quick refresher about types and design ond and third decades of the 20th century, to start. The ability to lay hands on enough served as a starting point for the satisfaction practical information to solve problems or of high-temperature engineering require- answer questions about the superalloys is the ments. They soon were found to be limited basis for this book. The ability to know in their strength capabilities. The metallurgi- enough to ask questions and/or delve further cal community responded to increased needs into the field is the basis for this by making what might be termed ‘‘super-al- chapter! loys’’ of stainless varieties. Of course, it was The primer provided in this chapter sup- not long before the hyphen was dropped and ports such needs as those described previ- the improved -base materials became ously by providing a concise overview of the known as superalloys. Concurrently, with the major topics considered in the book, starting advent of World War II, the be- with a little history and then a statement came a high driver for alloy invention or ad- about the nature of superalloys. This primer aptation. Although patents for aluminum and introduces the reader simply and directly to additions to -type alloys the wide variety of topics that must be con- were issued in the 1920s, the superalloy in- sidered in the application of superalloys. As dustry emerged with the adaption of a for the book, whether the user is familiar with alloy (Vitallium, also known as Haynes Stel- basic superalloy or is a complete lite 31) used in dentistry to satisfy high-tem- novice, this book provides a single-volume perature strength requirements of aircraft en- approach to the subject of superalloys. The- gines. Some - alloys (the ory is kept to a minimum, with practical Inconels and Nimonics), based more or less, knowledge stressed. one might say, on toaster wire (Nichrome, a If you are new to the subject, start with nickel-chromium alloy developed in the first this primer; it may be all that you need. If decade of the 20th century) were also avail- you are somewhat or strongly knowledgeable able. So, the race was on to make superior © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

2 / Superalloys: A Technical Guide alloys available for the insatiable thirst timate strength. However, when temperatures of the designer for more high-temperature rise, particularly to temperatures (on an ab- strength capability. It continues yet! solute temperature scale) of about 50% of the melting point/range for an alloy, strengths must be reckoned in terms of the time over What Are Superalloys and What which they are measured. Thus, if a metal is subjected to a load considerably less than the Can You Do to Them? load (stress) that would break it at room tem- perature, but is at a high temperature, then the Superalloys are nickel-, iron-nickel-, and metal will begin to extend with time at load. cobalt-base alloys generally used at temper- This time-dependent extension is called atures above about 1000 ЊF (540 ЊC). The and, if allowed to continue long iron-nickel-base superalloys such as the pop- enough, will lead to fracture (or rupture, as ular alloy IN-718 are an extension of stain- it is called). Thus the creep strength of a less technology and generally are metal or its rupture strength (technically wrought. Cobalt-base and nickel-base super- called creep-rupture strength but more com- alloys may be wrought or cast, depending on monly called stress-rupture strength) or both the application/composition involved. are necessary components of understanding A large number of alloys have been in- its mechanical behavior just as much as are vented and studied; many have been pat- the customary yield and ultimate strengths. ented. However, the many alloys have been Similarly, the (cyclic) capability will winnowed down over the years; only a few be reduced. So, to fully validate the capabil- are extensively used. Alloy use is a function ity of a metal alloy, dependent on application of industry (gas turbines, steam turbines, temperature and load, it may be necessary to etc.). Not all alloys can be mentioned; ex- provide yield and ultimate strengths, creep amples of older and newer alloys are used to strengths, stress-rupture strengths, and appro- demonstrate the physical metallurgy response priate fatigue strengths. Related mechanical of superalloy systems (see Chapters 3 and properties such as dynamic modulus, crack 12). Figure 1.1 compares stress-rupture be- growth rates, and fracture toughness also may havior of the three alloy classes (iron-nickel-, be required. Appropriate physical properties nickel-, and cobalt-base). A representative such as thermal expansion coefficient, den- list of superalloys and compositions, empha- sity, and so on complete the property list. sizing alloys developed in the United States, is given in Tables 1.1 and 1.2. Appropriate compositions of superalloys can be forged, rolled to sheet, or otherwise Basic Metallurgy of Superalloys produced in a variety of shapes. The more highly alloyed compositions normally are Iron, nickel, and cobalt are generally face- processed as castings. Fabricated structures centered cubic (fcc-austenitic) in crystal can be built up by welding or brazing, but structure when they are the basis for super- many highly alloyed compositions containing alloys. However, the normal room-tempera- a large amount of hardening phase are diffi- ture structures of iron and cobalt elemental cult to weld. Properties can be controlled by are not fcc. Both iron and cobalt un- adjustments in composition and by process- dergo transformations and become fcc at high ing (including heat treatment), and excellent temperatures or in the presence of other ele- elevated-temperature strengths are available ments alloyed with iron and cobalt. Nickel, in finished products. on the other hand, is fcc at all temperatures. In superalloys based on iron and cobalt, the fcc forms of these elements thus are generally stabilized by alloy element additions, partic- A Short Review of the High- ularly nickel, to provide the best properties. Temperature Strength of Metals The upper limit of use for superalloys is not restricted by the occurrence of any allo- At ordinary temperatures, the strengths of tropic phase transformation reactions but is a most metals are measured in terms of short- function of incipient melting temperatures time properties such as yield strength or ul- of alloys and dissolution of strengthening © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

Superalloys for High Temperatures—a Primer / 3

Fig. 1.1 Stress-rupture strengths of superalloys

phases. Incipient melting is the melting that densities of about 0.322 lb/in.3 (8.9 g/cm3). occurs in some part of the alloy that, when Iron-nickel-base superalloys have densities of solidified, is not at equilibrium composition about 0.285 to 0.300 lb/in.3 (7.9 to 8.3 g/ and thus melts at a lower temperature than cm3); cobalt-base superalloys, about 0.300 to that at which it might otherwise melt. All al- 0.340 lb/in.3 (8.3 to 9.4 g/cm3); and nickel- loys have a melting range, so melting is not base superalloys, about 0.282 to 0.322 lb/in.3 at a specific temperature even if there is no (7.8 to 8.9 g/cm3). Superalloy density is in- nonequilibrium segregation of alloy ele- fluenced by alloying additions: aluminum, ments. Superalloys are strengthened not only titanium, and chromium reduce density, by the basic nature of the fcc matrix and its whereas , , and in- chemistry but also by the presence of spe- crease it. The corrosion resistance of super- cial strengthening phases, usually precipi- alloys depends primarily on the alloying el- tates. Working (mechanical deformation, of- ements added, particularly chromium and ten cold) of a superalloy can also increase aluminum, and the environment experienced. strength, but that strength may not endure at The melting temperatures of the pure ele- high temperatures. ments are as follows: nickel, 2647 ЊF (1453 Some tendency toward transformation of ЊC); cobalt, 2723 ЊF (1495 ЊC); and iron, the fcc phase to stable lower-temperature 2798 ЊF (1537 ЊC). Incipient (lowest) melting phases occasionally occurs in cobalt-base su- temperatures and melting ranges of superal- peralloys. The austenitic fcc matrices of su- loys are functions of composition and prior peralloys have extended solubility for some processing. Generally, incipient melting tem- alloying additions, excellent ductility, and peratures are greater for cobalt-base than (iron-nickel- and nickel-base superalloys) for nickel- or iron-nickel-base superalloys. favorable characteristics for precipitation of Nickel-base superalloys may show incipient uniquely effective strengthening phases. melting at temperatures as low as 2200 ЊF Pure iron has a density of 0.284 lb/in.3 (1204 ЊC). Advanced nickel-base single-crys- (7.87 g/cm3), and pure nickel and cobalt have tal superalloys having limited amounts of © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

4 / Superalloys: A Technical Guide Composition, % (continued) Cr Ni Co Mo W Nb Ti Al Fe C Other A-286DiscaloyIncoloy 903Pyromet CTX-1Incoloy 907Incoloy 909Incoloy 925 0.1 max 0.1 max 14.0 15.0 37.7 38.0 . . . 26.0 26.0 . . . 20.5 16.0 15.0 38.4 ...... 44.0 38.0 0.1 0.1 13.0 13.0 . . 3.0 1.25 ...... 3.0 2.8 3.0 ...... 1.7 . . . . . 1.4 . 4.7 2.0 4.7 1.7 . . . 1.0 0.7 1.5 1.5 2.1 0.2 0.25 39.0 0.03 41.0 0.03 0.2 55.0 55.2 0.03 0.04 42.0 42.0 0.06 0.04 29 0.01 0.01 0.005 B, 0.3 V 0.01 0.15 Si . 0.4 . Si . . . . 1.8 Cu . . . Alloy N-155 (Multimet)Haynes 556I9-9 DLIncoloy 800Incoloy 800H 21.0Incoloy 800HTIncoloy 801Incoloy 802 20.0Haynes 214Haynes 230 22.0Inconel 600 20.0Inconel 601 21.0 21.0Inconel 19.0 21.0 617 21.0Inconel 625RA333 3.00 20.5 32.5Hastelloy 33.0 B 32.5 21.0 9.0Hastelloy 20.0 N 2.5Hastelloy S 16.0 32.0Hastelloy . W . . 22.0 . . 32.5 .Hastelloy . . . X . . 15.5 3.0 . 1.0Hastelloy C-276 23.0 76.5Haynes . HR-120 . 22.0 . 55.0Haynes . HR-160 . 21.5 . . 76.0 . . 2.5 . . . 75 . . . . 1.25 . 60.5 . 1.0Nimonic max 5.0 . 86 . max . 55.0 25.0 . 61.0 .Haynes 0.1 7.0 . . 25 . . 63.0 1.25 (L605) . 15.5 . . . .Haynes . . . . . 188 . 2.0 . . . . 15.5 5.0Alloy 12.5 S-816 45.0 . 22.0 . . 25.0MP35-N . . 2.5 0.4 . 72.0 . max ...... 28.0 67.0MP159 . . . . . 14.0 ...... . 59.0 61.0 . . . B 9.0 . 49.0 28.0UMCo-50 . 37.0 3.0 . 0.3 19.5 . . . . . 37.0 . . . . 20.0 . 2.5 32.2 . . 25.0 . 0.38 9.0 max . . . 1.5 . . 0.4 . . 0.3 . max ...... 3.0 75.0 3.0 . . . 24.5 29.0 . 10.0 . 22.0 16.0 1.13 65.0 . . . 15.5 . 9.0 0.15 20.0 . . . 0.75 . . 0.38 . . 16.0 ...... 0.4 . 29.0 3.0 . . . 2.5 . . 20.0 . . 50.0 . 22.0 ...... 3.6 . 20.0 . . 0.6 . 0.15 . 19.0 . . N, 30.0 . 3.7 0.2 0.58 . 28.0 45.7 . La, 66.8 . 0.35 . . . 0.02 . . . . 35.0 Zr 2.5 . . 37.0 . . 0.10 ...... 0.2 . . 46.0 42.0 ...... 10.0 . . 25.0 . . 45.8 . . . 4.5 . 1.0 . 3.0 . 0.7 . 35.0 max . 0.05 44.8 46.3 0.30 . 0.5 . . max 15.0 0.50 . . Ta, . . . . 1.0 0.02 . . 4.0 36.0 ...... 0.08 La, . . . . 1.35 . . . . 0.002 . . . 0.08 0.2 Zr 61.5 . . . . 10.0 0.10 . 49.0 . . . 1.10 . 0.35 0.05 14.5 3.0 Mn, . . 0.60 . Si . 4.0 . . 7.0 . . . . 0.8 . . . . . Mn, . 0.5 14.1 . . . . . Si, . 2.0 . 8.0 . . 0.4 . 0.015 . . 0.2 . . Cu 5.0 max . . . . B, 2.5 . 4.0 . 0.02 . . 0.03 . 0.1 La . 5.0 . 0.4 . max ...... 4.5 . 0.05 . 18.0 0.05 . . 0.08 . max . . . 0.07 . . . 15.8 . . . 0.05 5.5 . . 0.6 . 0.06 1.0 . . 33.0 . . 0.03 . 5.0 . 0.15 V . . . 0.5 . . . . . Cu . . 0.05 0.25 . . . . Cu . 0.12 . max 3.0 0.15 0.02 max 2.0 . . . 0.02 . . max 0.05 . . . . 0.6 . . V . 2.5 0.02 . 3.0 La ...... 0.05 0.2 3.0 0.7 . max . Mn, . . 0.6 . Si, . . . 0.2 4.0 0.12 . . N, 0.10 . 0.004 . B . 2.75 . . 0.10 Si, . . 0.05 . 0.5 . Mn . . . . . 9.0 . . . 0.25 0.38 1.5 max Mn Cu 0.90 1.0 0.03 La Ce, 0.015 21.0 Mg ...... 1.0 0.12 ...... Iron-nickel-base Iron-nickel-base Nickel-base Cobalt-base Precipitation-hardening alloys Table 1.1 Nominal compositions of wrought superalloys Alloy Solid-solution alloys © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

Superalloys for High Temperatures—a Primer / 5 Ta), 0.15 max Cu ϩ Zr Zr ϩ ϩ B, B, ϩ ϩ Composition, % Cr Ni Co Mo W Nb Ti Al Fe C Other 718Inconel 721Inconel 722Inconel 725Inconel 751Inconel X-750M-252MERL-76Nimonic 80A 19.0Nimonic 90 16.0Nimonic 95 15.5Nimonic 100 21.0Nimonic 105 15.5 52.5 15.5Nimonic 115 71.0C-263 75.0Pyromet . 860 . . 57.0Pyromet 19.5 12.4 . 31 . 19.0 . 73.0 72.5Refractaloy . 26 . . 19.5Rene . 41 . . 19.5Rene . . 88 11.0 . . . .Rene 73.0 54.4 95 15.0 56.5 3.0Rene . 100 15.0 . . 55.5Udimet . 500 . 18.6 . 53.5Udimet 1.0 10.0 520 56.0 13.0 . 8.0 .Udimet . . . 18.0 630 54.0 . . . 18.0 . 20.0 22.7Udimet . 18.0 700 55.0 . . 20.0Udimet . 710 . . . 20.0 .Udimet . 10.0 3.3 . . 720 44.0 . 5.1 15.0Udimet . . . 720LI 19.0 . . . . . 38.0 . 51.0 55.5Unitemp . . AF2-1DA 16 . . . . . 0.9 . . . 5.0 . 14.0 . 4.0 . . . 3.5 19.0 . 20.0 . 5.0 20.0 9.5 . . . . 19.0 3.0 1.0 1.0 . 4.0 55.0 . . 17.0 1.5 2.4 ...... 15.0 1.4 56.4 . . 61.0 . . 2.5 0.5 2.3 . 11.0 12.0 48.0 6.0 . 18.0 . . 61.0 . . 3.2 . 5.9 57.0 18 16 . . 4.3 13.0 . . . 2.6 50.0 2.0 . . . 8.0 19.0 . . 0.35 0.7 . . 15.0 . 2.25 max 53.0 . . . 12.0 . . . . 10.0 . 59.0 55.0 . 0.7 1.2 . 2.4 . . . . 19.5 18.5 . . . . 1.5 2.9 . . 18.5 55 57 9.0 5.1 4 1.2 10.0 1.0 14.8 . 3.5 . 4.0 1.4 . . 4.0 . . 3.0 . 6.5 . . 6.0 . . 7.0 . 57.0 0.08 1.4 1.1 14.8 max 15.0 7.0 7.0 5.0 2.0 3.0 . 0.03 5.0 3.0 . max . 3.5 4 . 2.6 . 4.7 2.1 . . 3.0 3.0 13.5 . . . . 2.5 1.0 0.15 <0.75 . 0.4 5.0 max Cu 0.04 1.5 . . . . . 3.5 . 3.0 3 3 0.04 0.05 3.1 . 0.7 . 1.5 . . . 1.0 6.0 1.5 . . 2.0 5.0 . . 0.15 max max 0.2 0.45 4.3 2.5 . 1.5 . 0.02 . 6.5 3.7 0.05 0.5 2.2 3.0 . Mn, Mn, . 4.2 1.0 3.0 . . . 0.2 0.1 0.30 0.15 . . 1.25 Cu, Cu 1.25 . max max . 0.4 0.25 0.25 1.5 0.06 Si . max max . 1.0 Cu Cu . 28.9 0.005 0.7 B 3.4 16.0 max . . 3.5 3.0 5.0 . . 0.35 . . 0.08 14.5 Hf, 2.1 0.10 0.20 3.0 0.06 max Zr Cu 5.5 2.0 . 0.06 . . . . 5 5 <0.3 . 0.7 0.05 0.03 4.3 4.6 2.5 0.04 <0.3 0.005 3.0 B 0.04 . Zr . 4.0 . max 1.0 . . . max 0.09 . . . 0.01 B 18.0 2.5 2.5 0.015 B 0.08 0.16 <1.0 0.005 0.16 B <0.5 . 1.4 . . 0.03 0.01 0.08 B 0.04 0.07 . . 0.005 . . 0.01 0.35 . . B 0.015 B, 0.05 B, 0.06 Zr 0.07 2.0 Zr, max 1.0 0.03 V Zr 0.005 B 0.004 B 0.07 0.03 B 1.5 0.035 0.025 Ta. 0.015 B, 0.01 0.1 B Zr 0.006 0.03 0.03 B, Zr Zr 0.09 Zr V-57W-545AstroloyCustom Age 625 PLUSHaynes 242Haynes 263Haynes R-41Inconel 100 21.0IN-100Inconel 102Incoloy 14.8 901 13.5Inconel 702 61.0 15.0Inconel 706 8.0 20.0 . . 27.0 19.0 . 26.0 56.5 10.0 . . . . . 62.5 . 52.0 15.0 15.0 52.0 10 12.5 8.0 2.5 60.0 15.5 max . . . 11.0 16.0 67.0 1.25 15.0 . 1.5 25.0 . 5.25 42.5 . 60 79.5 . . . 10.0 . 41.5 ...... 6.0 . . . 3.4 15 . 3.0 ...... 1.3 ...... 2.9 . . . . 6.0 3 . 3.0 . . . . 3.5 . 2.85 ...... 3.0 0.2 ...... 3.1 . . . 2.4 . . . 0.25 2.9 . 0.2 . 4.4 4.7 . 0.5 . max . . 0.5 5.0 1.5 ...... 0.6 . . 48.6 2.7 2.0 . max 5.5 55.8 <0.3 0.6 4.7 0.01 0.5 1.75 0.10 max 0.08 5.0 max . 0.08 . 0.06 . 0.7 max <0.6 0.006 max 3.2 5.5 B 0.2 0.01 . . B, . 0.5 0.05 max B 0.09 7.0 V 0.06 0.03 0.15 B, 36.2 0.06 Zr <0.6 37.5 1.0 0.06 0.5 Si, 0.1 0.6 Mn, Mn, 0.006 1.0 0.10 0.4 B V, max 0.06 Si, Zr, 0.2 0.15 0.015 Cu B 0.03 0.05 0.005 . B, . 0.02 . Mg, 0.03 Zr 0.06 Zr, 2.9 0.5 1.0 (Nb Mn, V 0.2 Cu, 0.4 Si Iron-nickel-base (continued) Nickel-base Table 1.1 (continued) Alloy Precipitation-hardening alloys (continued) © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

6 / Superalloys: A Technical Guide Nominal composition, % (continued) Hf also contains 1.5% Hf. (c) Designated R’ 162 in U.S. patent 5,270,123. Also contains 0.02–0.07% C, 0.003–0.01% B, 0–0.3% Y, ϩ C Ni Cr Co Mo Fe Al B Ti Ta W Zr Other Hf also contains 1.5% Hf. (b) MAR-M 200 ϩ Table 1.2 Nominal compositions of cast superalloys Alloy designation Nickel-base B-1900CMSX-2CMSX-4CMSX-6CMSX-10Hastelloy XInconel 100Inconel 713CInconel 0.1 713LC .Inconel . 738 . .Inconel . 792 . .Inconel . 64 718 . . . 0.1 .X-750 66.2 0.18M-252 bal 0.12 0.05MAR-M 200 bal 8 8 50 balMAR-M 246 60.5 74 0.17MAR-M 6.5 247 75 10 0.2PWA 1480 1.8–4.0 10 21 0.04PWA 1484 61.5 10 12.5Rene 1.5–9.0 4.6 12 41 60Rene 9 77 53 0.15 0.04 16 0.25–2.0Rene 5 80 0.15 0.15 15Rene 1 80 . 0.15 0.6 . 6 Hf . . 13Rene 59 . 73 . 100 19 . . . 60 56 0.6 . . . 59 5.0–7.0 8.5 3 . . . 3 . . . 15 . 9 4.2 9 . . 20 . . 0.09 9(a) 9 . 4.5 B-1900 . bal . . . . 0.07 . 8.25 56 1.75 bal . . 0.17 0.08 . . . . . 6 18 55 . . 10 . 5.6 0.1–1.2 10 . . . 58 . 0.18 . 10 . . 2.0 10 10 . 3 60 5 60 7.0–10.0 4.8 . . 19 6 5.5 . 0.015 . . 61 . . 15 . 6 3.5–7.5 . . . . 3.4 . 10 . . . 14 14 . 5.0 . 18 1 0.7 2.5 . 0.01 1 . 10 . . 0.012 . . . 9.5 11.0 1.0 . . 0.01 0.01 3.2 15 7 1 . . 5 . . . 0.8 0.5 0.5 . . . 4.7 . 9.5 9.5 4(a) 10.0 2 3.4 6 0.6 15 . . 0.02 . 6.5 5.5 0.7 5 . 1 . 4.2 . 5.5 . . . 1.75 2 4 4 ...... 4.2 . . . . . 4 . . 0.015 3 . . . 6 8 . 0.015 . . . 0.015 . 5.0 0.005 . 0.9 . . . . 0.10 1.5 . . 1 ...... 1.5 5.6 ...... 2 2.6 . 6 . . . 2.5 . 2.6 . . 4.3 . . . 0.1 1 . . . . 0.01 . . 3 3 0.06 . . . 0.1 . . 0.9 . 1.5 3 Nb 0.015 0.1 . 5.5 4 . 1.5 1 3.1 . . . . V ...... 2 . . . Nb . 0.015 0.015 . 3.3 . . 0.015 . 10 0.1 12 . 10 . . . 5 . . 4.8 12.5 ...... 4.2 . 2 Nb . 0.05 . . 9 . 0.05 0.05 . . 0.1 . . Cu, . . . . 5 . . Nb . 4.0 . . . 1 1.5 . . Nb(b) . . Hf ...... 0.25 . . Cu, . 0.9 . 6 Nb . . . . . 4 . . 0.04 4 ...... 0.02 0.03 0.06 0.75 Hf . 1 . V ...... and 0–6% Ru. © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

Superalloys for High Temperatures—a Primer / 7 Ta ϩ Nominal composition, % Hf also contains 1.5% Hf. (c) Designated R’ 162 in U.S. patent 5,270,123. Also contains 0.02–0.07% C, 0.003–0.01% B, 0–0.3% Y, ϩ C Ni Cr Co Mo Fe Al B Ti Ta W Zr Other Hf also contains 1.5% Hf. (b) MAR-M 200 ϩ and 0–6% Ru. Table 1.2 (continued) Alloy designation Nickel-base (continued) Rene N4RR 2000SRR99Rene N5Rene N6(c)Udimet 500Udimet 700Udimet 0.06 710Waspaloy ...... WAX-20(DS) . . . . 62 . .Cobalt-base 0.1 bal 0.1 balAiResist 13 0.13 9.8AiResist 213 8 0.20 bal balAiResist 10 0.07 215 53FSX-414 53.5 55Haynes 4.25–6 21 7 7.5 18 72Haynes 15 25; 57.5 L-605 5J-1650 15 0.45 18 10–15 0.20MAR-M 19.5 302 . . 0.35 . 1.5MAR-M 322 17 8MAR-M ... 18.5 0.1 0.5–2 509 . . 0.25 .MAR-M 3 918 15 13.5 0.5 0.25NASA Co-W-Re . 0.5 ...... S-816 21 . 20 5.25 ... 0.85 4 10 2V-36 19 10 1.0 0.20 4.2Wi-52 . . 4.2 3 3 . 0.6 5–6.25 5.5 0.40 20 . . . 29 . 0.05 . . . 62 64 . . 27 . . . 27 5.5 . . 63 2 . . 1 0.004 ...... 4.25 10 . 21.5 . . . 20 . 54 3.5 19 . 52.5 ...... 6.2 3 0.4 2.2 21.5 . . . 1.2 . . 64 . 23.5 . . . 0.03 0.27 2.5 20 3 0.45 58 . 6.5 . . . . 4.8 3 . . 60.5 3.5 36 4.0 . 0.005 . 20 . . . 54.5 7–9.25 . . . 0.5 . . 20 . . . . . 52 3 . 0.5 . 67.5 . . . . . 20 . . . . 3.5 . 5–6.5 . . . . 3.4 6 10 . . . 25 3 . 1 ...... 1 4.3 5 21 ...... 1 ...... 42 0.5 . . . . . 7 . . . . 0.5 . . 42 ...... 63.5 ...... 0.5 ...... Nb, . . . . . 0.15 . 0.010 ...... Hf ...... 5 ...... 0.005 . 1.5 . 20 . . 6.5 . . . 0.09 2 . . . . 0.02 . . 7.5 . . 4 ...... 3 . 0.08 . 2 ...... 0.75 . . 3.8 . . 1.5 . . 4.5 . . 0.2 . . . . . 11 ...... 4.5 9 . . . . . 1 ...... 4.5 . 0.1 7.5 2 0.1 3.5 . . 15 ...... 0.1 10 . . Y ...... 0.1 . 9 . . 7.5 Y 0.1 Y 12 . . . 7 ...... 0.2 . . . . 2 . . 25 ...... 0.5 . . . 5 . . . Mo . . . . . 0.1 1 . . . . 4 . . . 11 2 2 Re ...... 4 Mo, 2 4 Nb 4 Nb, Mo, 1.2 2 Mn, Nb, 0.4 1 Si Mn, 0.4 Si X-40 (Stellite alloy 31)(a) B-1900 0.50 10 22 57.5 . . . 1.5 ...... 7.5 . . . 0.5 Mn, 0.5 Si © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

8 / Superalloys: A Technical Guide melting-point depressants tend to have incip- loys remained similar to original levels or ient melting temperatures equal to or in ex- even increased. However, resistance to cess of those of cobalt-base superalloys. other types of corrosion attack decreased. • Superalloys have great oxidation resis- Some Superalloy tance, in many instances, but not enough Characteristics and Facts corrosion resistance. For many applica- tions at the highest temperatures, above • When temperatures go above about 1000 about 1400 ЊF (760 ЊC), as in aircraft tur- ЊF (540 ЊC), ordinary steels and titanium bines, superalloys must be coated. For alloys are no longer strong enough for ap- very long-time applications at tempera- plication. Steels also may suffer from en- tures at or above about 1200 ЊF (649 ЊC), hanced corrosion attack. as in land-based gas turbines, superalloys • When the highest temperatures (below the may have to be coated. melting temperatures, which are about • technology is an integral part of 2200 to 2500 ЊF (1204 to 1371 ЊC) for most superalloy development and application. alloys) must be achieved and strength is the Lack of a coating means much less ability consideration, then nickel-base superalloys to use superalloys for extended times at are the materials of choice. elevated temperatures. • Nickel-base superalloys can be used to a • Many alloy elements are added to super- higher fraction of their melting points than alloys in minuscule to major amounts, par- just about any other commercially avail- ticularly in the nickel-base alloys. Con- able materials. Refractory metals have trolled alloy elements could be as many as higher melting points than superalloys but 14 or so in some alloys. do not have the same desirable character- • Nickel and cobalt as well as chromium, istics as superalloys and are much less tungsten, , rhenium, , widely used. and other elements used in superalloys are • Cobalt-base superalloys may be used in often expensive and strategic elements that lieu of nickel-base superalloys, dependent may vary considerably in price and avail- on actual strength needs and the type of ability over time. corrosive attack expected. • At lower temperatures, and dependent on the type of strength needs for an applica- Applications tion, iron-nickel-base superalloys find more use than cobalt- or nickel-base superalloys. The high-temperature applications of superal- • Superalloy strength properties are directly loys are extensive, including components for related not only to the chemistry of the aircraft, chemical plant equipment, and pet- alloy but also to melting procedures, forg- rochemical equipment. Figure 1.2 shows the ing and working processes, casting tech- F119 engine, which is the latest in a series of niques, and, above all, to heat treatment military engines to power high-performance following forming, or casting. aircraft. The gas temperatures in these engines • Iron-nickel-base (sometimes designated in the hot sections (rear areas of the engine) nickel-iron-base) superalloys such as IN- may rise to levels far above 2000 ЊF (1093 718 are less expensive than nickel-base or ЊC). Cooling techniques reduce the actual cobalt-base superalloys. component metal temperatures to lower levels, • Most wrought superalloys have fairly high and superalloys that can operate at these tem- levels of the metal chromium to provide peratures are the major components of the hot corrosion resistance. In the cast alloys, sections of such engines. chromium was high to start but was signif- The significance of superalloys in today’s icantly reduced over the years in order to commerce is typified by the fact that, accommodate other alloy elements that in- whereas in 1950 only about 10% of the total creased the elevated temperature strength weight of an aircraft gas turbine engine was of superalloys. In the superalloys based on made of superalloys, by 1985 this figure had nickel, the aluminum content of the alloys risen to about 50%. Table 1.3 lists some cur- increased as chromium decreased. Thus, rent applications of superalloys. It will be the oxidation resistance of nickel superal- noted, however, that not all applications re- © 2002 ASM International. All Rights Reserved. www.asminternational.org Superalloys: A Technical Guide (#06128G)

Superalloys for High Temperatures—a Primer / 9

Fig. 1.2 F119 gas turbine engine—a major user of superalloys

Table 1.3 Some Applications of Superalloys quire elevated-temperature strength capabil- Aircraft/industrial gas turbine components: ity. Their high strength coupled with corro- Disks sion resistance have made certain superalloys Bolts Shafts standard materials for biomedical devices. Cases Superalloys also find use in cryogenic Blades applications. Vanes Combustors Afterburners Thrust reversers power plant components: What to Look for in This Book Bolts Blades Stack-gas reheaters The text provides those who desire it a very Selected automotive components, such as: complete understanding of superalloys. The Turbochargers chapters ‘‘Selection of Superalloys,’’ ‘‘Under- Exhaust Metal processing, such as in: standing Superalloy Metallurgy,’’ ‘‘Structure/ Hot work tools and dies Property Relationships,’’ plus ‘‘Corrosion and Casting dies Protection of Superalloys’’ enhance ability to Medical components, such as in: Dentistry make design decisions on superalloy use. Prosthetic devices For those involved in processing the su- Space vehicle components, such as: peralloys, virtually all process operations are Aerodynamically heated skins Rocket-engine parts included, starting with a very comprehensive equipment: look at the initial formulation of superalloys Trays in the chapter ‘‘Melting and Conversion.’’ Fixtures Conveyor belts Subsequently, the gamut of operations is cov- Nuclear power systems: ered from casting to machining and finishing. Control-rod drive mechanisms If you are experiencing problems with su- stems peralloys, reference to the chapters men- Springs Ducting tioned in the first paragraph of this section is Chemical and petrochemical industries: in order. If failures are occurring, check the Bolts chapter ‘‘Failure and Refurbishment.’’ Valves Reaction vessels For those desiring a little retrospective look at the current state of superalloy appli- Pumps cations and potential future directions, the Adapted from Titanium: A Technical Guide, 1st ed. chapter ‘‘Superalloys—Retrospect and Fu- ture Prospects’’ may be of interest.