Introduction to Selection of Titanium Alloys

Total Page:16

File Type:pdf, Size:1020Kb

Introduction to Selection of Titanium Alloys © 2000 ASM International. All Rights Reserved. www.asminternational.org Titanium: A Technical Guide, 2nd Edition (#06112G) Chapter 2 Introduction to Selection of Titanium Alloys General Background composition. Titanium aluminide alloys show • Bar promise for applications at temperatures up to • Sheet 760 °C (1400 °F). • Strip TITANIUM is a low-density element (ap- Titanium and titanium alloys are produced in • Tube proximately 60% of the density of steel and a wide variety of product forms, with some ex- • Plate superalloys) that can be strengthened greatly by amples shown in Fig. 2.1. Titanium can be alloying and deformation processing. (Charac- wrought, cast, or made by P/M techniques. It Nonmill products teristic properties of elemental titanium are may be joined by means of fusion welding, given in Table 2.1.) Titanium is nonmagnetic brazing, adhesives, diffusion bonding, or fas- • Sponge and has good heat-transfer properties. Its coef- teners. Titanium and its alloys are formable and • Powder ficient of thermal expansion is somewhat lower readily machinable, assuming reasonable care than that of steel and less than half that of alu- is taken. Customized product forms minum. Titanium and its alloys have melting Some specific examples of product forms are: points higher than those of steels, but maxi- • Forgings mum useful temperatures for structural applica- Mill products • P/M items tions generally range from as low as 427 °C • Castings (800 °F) to the region of approximately 538 °C • Ingot to 595 °C (1000 °F to 1100 °F), dependent on • Billet One of many different types of investment cast titanium parts now produced is shown in Fig. 2.2. Figure 2.3 shows a large forged titanium part. This part weighs approximately 1400 kg Table 2.1 Physical and mechanical properties of elemental titanium (3000 lb). Titanium has the ability to passivate and Property Description or value thereby exhibit a high degree of immunity Atomic number 22 against attack by most mineral acids and chlo- Atomic weight 47.90 Atomic volume 10.6 W/D rides. Pure titanium is nontoxic; commercially Covalent radius 1.32 Å pure titanium and some titanium alloys gener- Ionization potential 6.8282 V ally are biologically compatible with human Thermal neutron absorption cross section 5.6 barns/atom Crystal structure tissues and bones. Alpha (≤882.5 °C, or 1620 °F) Close-packed hexagonal The excellent corrosion resistance and Beta ( ≥882.5 °C, or 1620 °F) Body-centered cubic biocompatibility coupled with good strengths Color Dark gray make titanium and its alloys useful in chemical Density 4.51 g/cm3 (0.163 lb/in.3) Melting point 1668 ± 10 °C (3035 °F) and petrochemical applications, marine envi- Solidus/liquidus 1725 °C (3135 °F) ronments, and biomaterials applications. The Boiling point 3260 °C (5900 °F) combination of high strength, stiffness, good Specific heat (at 25 °C) 0.5223 kJ/kg ⋅ K toughness, low density, and good corrosion re- Thermal conductivity 11.4 W/m ⋅ K Heat of fusion 440 kJ/kg (estimated) sistance provided by various titanium alloys at Heat of vaporization 9.83 MJ/kg very low to elevated temperatures allows Specific gravity 4.5 weight savings in aerospace structures and Hardness 70 to 74 HRB Tensile strength 240 MPa (35 ksi) min other high-performance applications. Young’s modulus 120 GPa (17 × 106 psi) Poisson’s ratio 0.361 Coefficient of friction At 40 m/min (125 ft/min) 0.8 Selection of At 300 m/min (1000 ft/min) 0.68 Coefficient of linear thermal expansion 8.41 µm/m ⋅ K Titanium Alloys for Service Electrical conductivity 3% IACS (where copper = 100% IACS) Electrical resistivity (at 20 °C) 420 nΩ⋅m Electronegativity 1.5 Pauling’s Primary Aspects. Titanium and its alloys Temperature coefficient of electrical resistance 0.0026/°C are used primarily in two areas of application Magnetic susceptibility (volume, at room temperature) 180 ( ±1.7) × 10–6 mks where the unique characteristics of these metals © 2000 ASM International. All Rights Reserved. www.asminternational.org Titanium: A Technical Guide, 2nd Edition (#06112G) 6 / Titanium: A Technical Guide (d) (a) (b) (c) (e) (f) (g) Fig. 2.1 Some titanium and titanium alloys product forms. (a) Strip. (b) Slab. (c) Billet. (d) Wire. (e) Sponge. (f) Tube. (g) Plate. Courtesy of Teledyne Wah Chang Albany Fig. 2.2 Investment cast titanium transmission case for Osprey vertical take-off and landing aircraft Fig. 2.3 Forged titanium landing gear beam for Boeing 757 aircraft © 2000 ASM International. All Rights Reserved. www.asminternational.org Titanium: A Technical Guide, 2nd Edition (#06112G) Introduction to Selection of Titanium Alloys / 7 justify their selection: corrosion-resistant ser- Ti-6V-2Sn-2Zr-2Cr-2Mo+Si are used or Selection for Corrosion Resistance. Eco- vice and strength-efficient structures. For these planned for use in aircraft or in gas turbine en- nomic considerations normally determine two diverse areas, selection criteria differ gines for aerospace applications. whether titanium alloys will be used for corro- markedly. Corrosion applications normally use Desired mechanical properties such as yield sion service. Capital expenditures for titanium lower-strength “unalloyed” titanium mill prod- or ultimate strength to density (strength effi- equipment generally are higher than for equip- ucts fabricated into tanks, heat exchangers, or ciency), fatigue crack growth rate, and fracture ment fabricated from competing materials such reactor vessels for chemical-processing, desali- toughness, as well as manufacturing consider- as stainless steel, brass, bronze, copper nickel, nation, or power-generation plants. In contrast, ations such as welding and forming require- or carbon steel. As a result, titanium equipment high-performance applications such as gas tur- ments, are extremely important. These factors must yield lower operating costs, longer life, or bines, aircraft structures, drilling equipment, normally provide the criteria that determine the reduced maintenance to justify selection, which and submersibles, or even applications such as alloy composition, structure (alpha, alpha-beta, most frequently is made on a lower total- biomedical implants, bicycle frames, and so or beta), heat treatment (some variant of either life-cycle cost basis. on, typically use higher-strength titanium al- annealing or solution treating and aging), and Commercially pure (CP) titanium satisfies loys. However, this use is in a very selective level of process control selected or prescribed the basic requirements for corrosion service. manner that depends on factors such as thermal for structural titanium alloy applications. A Unalloyed titanium normally is produced to environment, loading parameters, corrosion en- summary of some commercial and semi- requirements such as those of ASTM standard vironment, available product forms, fabrica- commercial titanium grades and alloys is given specifications B 265, B 338, or B 367 in tion characteristics, and inspection and/or reli- in Table 2.2. grades 1, 2, 3, and 4 in the United States. These ability requirements (Fig. 2.4). Alloys for For lightly loaded structures, where titanium grades vary in oxygen and iron content, which high-performance applications in strength-effi- normally is selected because it offers greater re- control strength level and corrosion behavior, cient structures normally are processed to more sistance to the effects of temperature than alu- respectively. For certain corrosion applica- stringent and costly requirements than “unal- minum offers, commercial availability of re- tions, Ti-0.2Pd (ASTM grades 7, 8, and 11) loyed” titanium for corrosion service. As exam- quired mill products, along with ease of may be preferred over unalloyed grades 1, 2, ples of use, alloys such as Ti-6Al-4V and fabrication, may dictate selection. Here, one of 3, and 4. Ti-3Al-8V-6Cr-4Mo-4Zr are being used for the grades of unalloyed titanium usually is cho- Selection for Strength and Corrosion Re- offshore drilling applications and geothermal sen. In some cases, corrosion resistance, not sistance. Due to its unique corrosion behavior, piping, while alloys such as Ti-6Al-4V, strength or temperature resistance, may be the titanium is used extensively in prosthetic de- Ti-6Al-2Sn-4Zr-2Mo+Si, Ti-10V-2Fe-3Al, and major factor in selection of a titanium alloy. vices such as heart-valve parts and load-bearing (a) (b) (c) (d) Fig. 2.4 A few typical areas of application for high-performance titanium parts. (a) Offshore drilling rig components. (b) Subsea equipment and submersibles requiring ultrastrength. (c) Aircraft. (d) Components for marine and chemical processing operations. © 2000 ASM International. All Rights Reserved. www.asminternational.org Titanium: A Technical Guide, 2nd Edition (#06112G) 8 / Titanium: A Technical Guide hip and other bone replacements. In general, and at the same time to have sufficient total weight of all titanium alloys shipped. Dur- body fluids are chloride brines that have pH workability to be fabricated into mill products ing the life of the titanium industry, various values from 7.4 into the acidic range and also suitable for a specific application. compositions have had transient usage; contain a variety of organic acids and other Selection for Other Property Reasons. Ti-4A1-3Mo-1V, Ti-7A1-4Mo, and Ti-8Mn components—media to which titanium is to- Optic-system support structures arealit- are a few examples. Many alloys have been in- tally immune. Ti-6Al-4V normally is employed tle-known but very important structural appli- vented but have never seen significant commer- for applications requiring higher strength, but cation for titanium. Complex castings are used cial use. Ti-6Al-4V alloy is unique in that it other titanium alloys are used as well. Moder- in surveillance and guidance systems for air- combines attractive properties with inherent ately high strength is important in the applica- craft and missiles to support the optics where workability (which allows it to be produced in tion of titanium to prosthetics, but strength effi- wide temperature variations are encountered in all types of mill products, in both large and ciency (strength to density) is not the prime service.
Recommended publications
  • Cobalt Chrome Alloy Strength Without Size… Achieving Rigid Fixation Without the Bulk
    Cobalt Chrome Alloy Strength Without Size… Achieving Rigid Fixation Without the Bulk • Cobalt Chrome Alloy Rod, 5.5mm Diameter • Polaris™ Deformity System • Trivium™ Derotation System Customizable Spinal Deformity Correction The Polaris™ Deformity System is available in Titanium and Stainless Steel in both 5.5mm and 6.35mm diameter rods. We now offer three tensile strengths of Cobalt Chrome Alloy in 5.5mm diameter rods. Our rod options offer you the ability to customize deformity correction based on curve type, curve stiffness and rigidity, and desired curve correction. Polaris™ Cobalt Chrome Alloy and Stainless Steel rods are Titanium rods are offered in three grades. offered in three tensile strengths. Cobalt Chrome Alloy Stainless Steel Titanium • Available in 5.5mm • Available in 5.5mm • Available in 5.5mm and 6.35mm and 6.35mm • Imaging advantages due • Offered in Titanium alloy and Commercially Pure Titanium to its use with titanium • Retains the initial bend screws and hooks and provides rigid fixation • Less exertion required for bending • Maintaining high strength • Imaging advantages without compromising profile Low Standard CP Ti 5.5mm and Ti Alloy 5.5mm 6.35mm High Ti Alloy 6.35mm Material Comparison Characteristics Cobalt Chrome Alloy Stainless Steel Titanium Stiffness High High Low Strength High High Medium Corrosion Resistance Medium Low High Notch Sensitivity Medium Low High Imaging Compatibility Medium Low High Cobalt Chrome Alloy for Spinal Deformity Correction The Polaris™ Deformity System offers a 5.5mm diameter Cobalt Chrome Alloy (CoCrMo) rod, which is offered in three tensile strengths for use with Polaris™ Titanium Implants. CoCrMo has a history of use in various orthopedic implants, and provides rigid fixation while maintaining imaging capability.
    [Show full text]
  • Exploring Density
    Exploring Density Students investigate the densities of different liquids and solids and understand how density may help identify a substance. Suggested Grade Range: 6-8 Approximate Time: 1 hour Relevant National Content Standards: Next Generation Science Standards Science and Engineering Practices: Developing and using Models Modeling in 6–8 builds on K–5 experiences and progresses to developing, using, and revising models to describe, test, and predict more abstract phenomena and design systems. • Develop and use a model to describe phenomena. Science and Engineering Practices: Analyzing and Interpreting Data Analyzing data in 6-8 builds on K-5 and progresses to extending quantitative analysis to investigations, distinguishing between correlation and causation, and basic statistical techniques of data and error analysis. • Analyze and interpret data to determine similarities and differences in findings. Disciplinary Core Ideas: PS1.A Structure and Properties of Matter Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it. Common Core State Standard: 7NS 2. Apply and extend previous understanding of multiplication and division and of fractions to multiply and divide rational numbers. 3. Solve real-world and mathematical problems involving the four operations with rational numbers. Common Core State Standard: 7EE Solve real-life and mathematical problems using numerical and algebraic expressions and equations. 4. Use variables to represent
    [Show full text]
  • Titanium Alloy Data Sheet
    M Titanium Alloy Data Sheet Description Titanium equipment is often used in severe corrosive environments encountered in the chemical processing industries. Titanium has been considered an exotic “wonder metal” by many. This was particularly true in reference to castings. However, increasing demands and rapidly advancing technology have permitted titanium castings to be commercially available at an economical cost. The combination of its cost, strength, corrosion resistance, and service life in very demanding corrosive environments suggest its selection in applications where titanium castings have never been considered in the past. Specifications Flowserve’s commercially pure titanium (C.P.-Ti) castings conform to ASTM Specification B367, Grade C-3. Flowserve’s palladium stabilized titanium (Ti-Pd) castings conform to Grade Ti-Pd 8A. Composition C.P.-Ti (C-3) Ti-Pd (8A) Element Percent Percent Nitrogen 0.05 max. 0.05 max. Carbon 0.10 max. 0.10 max. Hydrogen 0.015 max. 0.015 max. Iron 0.25 max. 0.25 max. Oxygen 0.40 max. 0.40 max. Titanium Remainder Remainder Palladium –– 0.12 min. Minimum C.P.-Ti (C-3) & Mechanical Ti-Pd (8A) and Physical Tensile Strength, psi 65,000 Properties MPa 448 Yield Strength, psi 55,000 MPa 379 Elongation, % in 1" (25 mm), min. 12 Brinell Hardness, 3000 kg, max. 235 Modulus of Elasticity, psi 15.5 x 106 MPa 107,000 Coefficient of Expansion, in/in/°F@ 68-800°F 5.5 x 10-6 m/m/°C @ 20-427°C 9.9 x 10-6 Thermal Conductivity, Btu/hr/ft/ft2/°F @ 400° 9.8 WATTS/METER-KELVIN @ 204°C 17 Density lb/cu in 0.136 kg/m3 3760 Melting Point, °F (approx.) 3035 °C 1668 Titanium Alloy Data Sheet (continued) Corrosion The outstanding mechanical and physical properties of titanium, combined with its Resistance unexpected corrosion resistance in many environments, makes it an excellent choice for particularly aggressive environments like wet chlorine, chlorine dioxide, sodium and calcium hypochlorite, chlorinated brines, chloride salt solutions, nitric acid, chromic acid, and hydrobromic acid.
    [Show full text]
  • Fighting Wear and Corrosion on Stainless Steel and Titanium Accept …And Remember First - a Closer Look at Titanium Allotropic Crystal Structure
    AcceptLearn Structure: 1. General Titanium & Titanium alloy knowledge 2. ExpaniteHard-Ti Fighting wear and corrosion on stainless steel and titanium Accept …And remember First - A closer look at Titanium Allotropic crystal structure “Soft one” “Hard one” Extremely generalized a (HCP) 882.5°C b (BCC) Learn First - A closer look at Titanium Classification and general properties: Commercially pure (CP) titanium, alpha and near alpha titanium alloys - Generally non-heat treatable and weldable - Medium strength, good creep strength, good corrosion resistance Alpha-beta titanium alloys - Heat treatable, good forming properties - Medium to high strength, good creep strength Beta titanium alloys - Heat treatable - Readily formable (in solution treated condition) - Very high strength, low ductility Learn First - A closer look at Titanium Classification and general properties: Alpha stabilizers: Al, Sn, O & N a a+b b Beta stabilizers: V, Mo, Cr, Cu, W, Nb. Learn First - A closer look at Titanium Classification and general properties: a - stabilized phase diagram Alpha stabilizers: Al, Sn, O & N Pure titanium 882.5°C a a+b b Beta stabilizers: V, Mo, Cr, Cu, W, Nb. Degree of alloying elements Accept First - A closer look at Titanium a Heat treatment Annealing at 700C produces a-phase Quenching from the b phase field results in a martensitic transformation, i.e. b is converted to HCP-a’ (with some retained b) Air cooling from the b phase field results in a so- called Widmanstätten structure of a-plates Accept First - A closer look at Titanium Near-a Heat treatment The alloy is heated up to the b region • Air-cooling gives Widmanstätten α structure with some b • Quenching gives transformation of b to lath α’ with some b; ageing results in precipitation of α.
    [Show full text]
  • Glossary of Terms
    GLOSSARY OF TERMS For the purpose of this Handbook, the following definitions and abbreviations shall apply. Although all of the definitions and abbreviations listed below may have not been used in this Handbook, the additional terminology is provided to assist the user of Handbook in understanding technical terminology associated with Drainage Improvement Projects and the associated regulations. Program-specific terms have been defined separately for each program and are contained in pertinent sub-sections of Section 2 of this handbook. ACRONYMS ASTM American Society for Testing Materials CBBEL Christopher B. Burke Engineering, Ltd. COE United States Army Corps of Engineers EPA Environmental Protection Agency IDEM Indiana Department of Environmental Management IDNR Indiana Department of Natural Resources NRCS USDA-Natural Resources Conservation Service SWCD Soil and Water Conservation District USDA United States Department of Agriculture USFWS United States Fish and Wildlife Service DEFINITIONS AASHTO Classification. The official classification of soil materials and soil aggregate mixtures for highway construction used by the American Association of State Highway and Transportation Officials. Abutment. The sloping sides of a valley that supports the ends of a dam. Acre-Foot. The volume of water that will cover 1 acre to a depth of 1 ft. Aggregate. (1) The sand and gravel portion of concrete (65 to 75% by volume), the rest being cement and water. Fine aggregate contains particles ranging from 1/4 in. down to that retained on a 200-mesh screen. Coarse aggregate ranges from 1/4 in. up to l½ in. (2) That which is installed for the purpose of changing drainage characteristics.
    [Show full text]
  • Carbon Dioxide
    Safetygram 18 Carbon dioxide Carbon dioxide is nonflammable, colorless, and odorless in the gaseous and liquid states. Carbon dioxide is a minor but important constituent of the atmosphere, averaging about 0.036% or 360 ppm by volume. It is also a normal end-prod- uct of human and animal metabolism. Dry carbon dioxide is a relatively inert gas. In the event moisture is present in high concentrations, carbonic acid may be formed and materials resistant to this acid should be used. High flow rates or rapid depressurization of a system can cause temperatures approaching the sublimation point (–109.3°F [–78.5°C]) to be attained within the system. Carbon dioxide will convert directly from a liquid to a solid if the liquid is depressurized below 76 psia (61 psig). The use of ma- terials which become brittle at low temperatures should be avoided in applications where temperatures less than –20°F (–29°C) are expected. Vessels and piping used in carbon dioxide service should be designed to the American Society of Mechanical Engineers (ASME) or Department of Transportation (DOT) codes for the pressures and temperatures involved. Physical properties are listed in Table 1. Carbon dioxide in the gaseous state is colorless and odorless and not easily detectable. Gaseous carbon dioxide is 1.5 times denser than air and therefore is found in greater concentrations at low levels. Ventilation systems should be designed to exhaust from the lowest levels and allow make-up air to enter at a higher level. Manufacture Carbon dioxide is produced as a crude by-product of a number of manufactur- ing processes.
    [Show full text]
  • Guidelines for the Use of Atomic Weights 5 10 11 12 DOI: ..., Received ...; Accepted
    IUPAC Guidelines for the us e of atomic weights For Peer Review Only Journal: Pure and Applied Chemistry Manuscript ID PAC-REC-16-04-01 Manuscript Type: Recommendation Date Submitted by the Author: 01-Apr-2016 Complete List of Authors: van der Veen, Adriaan; VSL Meija, Juris Possolo, Antonio; National Institute of Standards and Technology Hibbert, David; University of New South Wales, School of Chemistry atomic weights, atomic-weight intervals, molecular weight, standard Keywords: atomic weight, measurement uncertainty, uncertainty propagation Author-Supplied Keywords: P.O. 13757, Research Triangle Park, NC (919) 485-8700 Page 1 of 13 IUPAC Pure Appl. Chem. 2016; aop 1 2 3 4 Sponsoring body: IUPAC Inorganic Chemistry Division Committee: see more details on page XXX. 5 IUPAC Recommendation 6 7 Adriaan M. H. van der Veen*, Juris Meija, Antonio Possolo, and D. Brynn Hibbert 8 9 Guidelines for the use of atomic weights 5 10 11 12 DOI: ..., Received ...; accepted ... 13 14 Abstract: Standard atomicFor weights Peer are widely used Review in science, yet the uncertainties Only associated with these 15 values are not well-understood. This recommendation provides guidance on the use of standard atomic 16 weights and their uncertainties. Furthermore, methods are provided for calculating standard uncertainties 17 of molecular weights of substances. Methods are also outlined to compute material-specific atomic weights 10 18 whose associated uncertainty may be smaller than the uncertainty associated with the standard atomic 19 weights. 20 21 Keywords: atomic weights; atomic-weight intervals; molecular weight; standard atomic weight; uncertainty; 22 uncertainty propagation 23 24 25 1 Introduction 15 26 27 Atomic weights provide a practical link the SI base units kilogram and mole.
    [Show full text]
  • The Water Molecule
    Seawater Chemistry: Key Ideas Water is a polar molecule with the remarkable ability to dissolve more substances than any other natural solvent. Salinity is the measure of dissolved inorganic solids in water. The most abundant ions dissolved in seawater are chloride, sodium, sulfate, and magnesium. The ocean is in steady state (approx. equilibrium). Water density is greatly affected by temperature and salinity Light and sound travel differently in water than they do in air. Oxygen and carbon dioxide are the most important dissolved gases. 1 The Water Molecule Water is a polar molecule with a positive and a negative side. 2 1 Water Molecule Asymmetry of a water molecule and distribution of electrons result in a dipole structure with the oxygen end of the molecule negatively charged and the hydrogen end of the molecule positively charged. 3 The Water Molecule Dipole structure of water molecule produces an electrostatic bond (hydrogen bond) between water molecules. Hydrogen bonds form when the positive end of one water molecule bonds to the negative end of another water molecule. 4 2 Figure 4.1 5 The Dissolving Power of Water As solid sodium chloride dissolves, the positive and negative ions are attracted to the positive and negative ends of the polar water molecules. 6 3 Formation of Hydrated Ions Water dissolves salts by surrounding the atoms in the salt crystal and neutralizing the ionic bond holding the atoms together. 7 Important Property of Water: Heat Capacity Amount of heat to raise T of 1 g by 1oC Water has high heat capacity - 1 calorie Rocks and minerals have low HC ~ 0.2 cal.
    [Show full text]
  • Research on Selective Laser Melting of Ti6al4v: Surface Morphologies, Optimized Processing Zone, and Ductility Improvement Mechanism
    metals Article Research on Selective Laser Melting of Ti6Al4V: Surface Morphologies, Optimized Processing Zone, and Ductility Improvement Mechanism Di Wang 1,2 ID , Wenhao Dou 1 and Yongqiang Yang 1,* 1 School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China; [email protected] (D.W.); [email protected] (W.D.) 2 School of Metallurgy and Materials, The University of Birmingham, Birmingham B152TT, UK * Correspondence: [email protected]; Tel./Fax: +86-020-8711-1036 Received: 24 May 2018; Accepted: 15 June 2018; Published: 21 June 2018 Abstract: The quality and mechanical properties of titanium alloy fabricated using selective laser melting (SLM) are critical to the adoption of the process which has long been impeded by the lack of uniformity in SLM-fabrication parameter optimization. In order to address this problem, laser power and scanning speed were combined into linear energy density as an independent variable, while surface morphology was defined as a metric. Based on full-factor experiments, the surface quality of SLM-fabricated titanium alloy was classified into five zones: severe over-melting zone, high-energy density nodulizing zone, smooth forming zone, low-energy density nodulizing zone, and sintering zone. The mechanism resulting in the creation of each zone was analyzed. Parameter uniformity was achieved by establishing a parameter window for each zone, and it also revealed that under smooth forming conditions, the relationship of linear energy density to the quality of the formed surface is not linear. It was also found that fabrication efficiency could be improved in the condition of the formation of a smooth surface by increasing laser power and scanning speed.
    [Show full text]
  • Selective Laser Melting of Titanium Alloy with 50 Wt% Tantalum: Effect of Laser Process
    Title: Selective Laser Melting of Titanium Alloy with 50 wt% Tantalum: Effect of Laser Process Parameters on Part Quality Authors: Swee Leong Sing a,b, (S.L. Sing) [email protected] Florencia Edith Wiria a,c, (F.E. Wiria) [email protected] Wai Yee Yeong a,b, (W.Y. Yeong) [email protected] +65 6790 4343 (corresponding author) Affiliations: a SIMTech-NTU Joint Laboratory (3D Additive Manufacturing), Nanyang Technological University Address: HW3-01-01, 65A Nanyang Drive, Singapore 637333 b Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University Address: N3.1-B2C-03, 50 Nanyang Avenue, Singapore 639798 c Singapore Institute of Manufacturing Technology (SIMTech) @ NTU Address: 73 Nanyang Drive, Singapore 637662 Keywords: Additive manufacturing; 3D printing; Selective laser melting; Powder mixture; Titanium; Tantalum Abstract: Selective laser melting (SLM) is a powder bed fusion additive manufacturing (AM) technique that produces three-dimensional (3D) parts by fusing metallic powders with a high-energy laser. SLM involves numerous process parameters that may influence the properties of the final parts. Hence, establishing the effect of the SLM processing parameters is important for producing parts of high quality. In this study, titanium-tantalum alloy was fabricated by SLM using a customized powder blend to achieve in situ alloying. The influence of processing parameters on the microstructure and properties such as relative density, microhardness and surface roughness was investigated. The results show that fully dense titanium-tantalum parts can be obtained from SLM. With laser power of 360 W, scan speed of 400 mm/s, powder layer thickness of 0.05 mm and hatch spacing of 0.125 mm, the titanium-tantalum alloy produced by SLM has relative density of 99.85 ± 0.18 %.
    [Show full text]
  • Measuring Density
    Measuring Density Background All matter has mass and volume. Mass is a measure of the amount of matter an object has. Its measure is usually given in grams (g) or kilograms (kg). Volume is the amount of space an object occupies. There are numerous units for volume including liters (l), meters cubed (m3), and gallons (gal). Mass and volume are physical properties of matter and may vary with different objects. For example, it is possible for two pieces of metal to be made out of the same material yet for one piece to be bigger than the other. If the first piece of metal is twice as large as the second, then you would expect that this piece is also twice as heavy (or have twice the mass) as the first. If both pieces of metal are made of the same material the ratio of the mass and volume will be the same. We define density (ρ) as the ratio of the mass of an object to the volume it occupies. The equation is given by: M ρ = (1.1) V here the symbol M stands for the mass of the object, and V the volume. Density has the units of mass divided by volume such as grams per centimeters cube (g/cm3) or kilograms per liter (kg/l). Sample Problem #1 A block of wood has a mass of 8 g and occupies a volume of 10 cm3. What is its density? Solution 8g The density will be = 0.8g / cm 3 . 10cm 3 This means that every centimeter cube of this wood will have a mass of 0.8 grams.
    [Show full text]
  • Applications of an Aluminum-Beryllium Composite for Structural Aerospace Components
    Applications of an Aluminum -Beryllium Composite for Structural Aerospace Components William Speer and Omar S. Es -Said Mechanical Engineering Department, Loyola Marymount University, 7900 Loyola Blvd, Los Angeles, CA 90045 -8145, USA Abstract The us e of AlBeMet AM162, an aluminum -beryllium metal matrix composite, is an effective way to reduce the size and weight of many structural aerospace components that are currently made out of aluminum and titanium alloys. These savings, which are essential for today’s technologies, are primarily due to the material’s high modulus and low density combined with its better than average specific strength. The raw material costs are significantly higher than they are for traditional engineering alloys, and the avai lable billet sizes are more limited than they are for aluminum and titanium alloys. Although the material costs are higher for the aluminum -beryllium composite, ease of machining makes it financially competitive when compared to equivalent parts made out of titanium alloys. Due to toxic nature of beryllium, however, debris -generating operations must be strictly regulated to limit worker’s exposure to the material and protect them from potentially fatal diseases. Keywords: Metal matrix; AlBeMet; High el astic modulus; Low density; Weight reduction; Stiffness -driven design 1. Introduction The aerospace industry is continually searching for ways to reduce the weight of its products and maximize the amount of profit -making payload in launch vehicles. One o f the most common ways engineers reduce weight is to make their products out of low-density alloys or engineering composites. These materials offer very high strength and/or stiffness to weight ratios; therefore, they require less mass and take less space to support a given load in comparison to other material choices.
    [Show full text]