Elongation. 10% at 20 °C (70 °F) Elastic modulus. Tension: 315 GPa (46 × 10 6 psi) at 20 °C (70 °F); 180 GPa (26 × 10 6 psi) at 1095 °C (2000 °F) Mass Characteristics Density. 10.2 g/cm 3 (0.367 lb/in. 3 ) Thermal Properties Liquidus temperature. 2610 °C (4730 °F) Coefficient of linear thermal expansion. 6.1 μm/m · K (3.41 μin./in. · °F) at 20 to 1010 °C (68 to 1850 °F) Fabrication Characteristics Recrystallization temperature. 1315 to 1425 °C (2400 to 2600 °F) Stress-relief temperature. 1 h at 1095 to 1205 °C (2000 to 2200 °F) TZC Mo-1Ti-0.3Zr Chemical Composition Nominal composition. 1.25 Ti, 0.3 Zr, 0.15 C, bal Mo Applications Typical uses. Aerospace equipment and components Mechanical Properties Tensile properties. Stress relieved: tensile strength, 995 MPa (144 ksi); yield strength, 725 MPa (105 ksi); elongation, 22% in 50 mm (2 in.); reduction in area, 36%. At 1095 °C (2000 °F): tensile strength, 640 MPa (93 ksi). At 1315 °C (2400 °F): tensile strength, 415 MPa (60 ksi) TZM Mo-0.5Ti-0.1Zr Commercial Names UNS number. Arc cast, R03630; P/M, R03640 ASTM designation. Arc cast: molybdenum alloy 363. P/M: molybdenum alloy 364 Specifications ASTM. B 384, B 385, B 386, B 387 Chemical Composition Composition limits. Arc cast: 0.40 to 0.55 Ti, 0.06 to 0.12 Zr, 0.01 to 0.04 C, 0.010 Fe max, 0.010 Si max, 0.005 Ni max, 0.001 N max, 0.0030 O max, 0.0005 H max. For P/M products: 0.002 N max, 0.030 O max, and 0.005 Si max; all other limits remain the same. Applications Typical uses. Used in heat engines, heat exchangers, nuclear reactors, radiation shields, extrusion dies, boring bars Mechanical Properties Tensile properties. See Table 21. Table 21 Typical tensile properties of TZM Temperature Tensile strength Yield strength at 0.2% offset °C °F MPa ksi MPa ksi Elongation in 50 mm (2 in.), % Stress-relieved condition 20 70 965 140 860 125 10 1095 2000 490 71 435 63 . . . 1650 3000 83 12 62 9 . . . Recrystallized material 20 70 550 80 380 55 20 1095 2000 505 73 . . . . . . . . . 1315 2400 369 53.5 . . . . . . . . . Elastic modulus. Tension, 315 GPa (46 × 10 6 psi) at 20 °C (68 °F); 205 GPa (30 × 10 6 psi) at 1095 °C (2000 °F) Mass Characteristics Density. 10.16 g/cm 3 (0.367 lb/in. 3 ) at 20 °C (68 °F) Thermal Properties Liquidus temperature. 2620 °C (4750 °F) Coefficient of linear thermal expansion. 4.9 μm/m · K (2.7 μin./in. · °F) at 20 to 40 °C (68 to 100 °F) Thermal conductivity. See Fig. 22. Fig. 22 Thermal conductivities of TZM and selected other refractory metals and alloys Fabrication Characteristics Recrystallization temperature. 1425 to 1595 °C (2600 to 2900 °F) Stress-relief temperature. 1 h at 1095 to 1260 °C (2000 to 2300 °F) Tungsten Walter A. Johnson, Institute of Materials Processing, Michigan Technological University TUNGSTEN is consumed in four forms: • Tungsten carbide • Alloying additions • Pure tungsten • Tungsten-based chemicals Tungsten carbide accounts for about 65% of tungsten consumption. It is combined with cobalt as a binder to form the so- called cemented carbides, which are used in cutting and wear applications (see the article "Cemented Carbides" in this Volume). Metallic tungsten and tungsten alloy mill products account for about 16% of consumption. Tungsten and tungsten alloys dominate the market in applications for which a high-density material is required, such as kinetic energy penetrators, counterweights, flywheels, and governors. Other applications include radiation shields and x-ray targets. In wire form, tungsten is used extensively for lighting, electronic devices, and thermocouples. Tungsten chemicals make up approximately 3% of the total consumption and are used for organic dyes, pigment phosphors, catalysts, cathode-ray tubes, and x-ray screens. The high melting point of tungsten makes it an obvious choice for structural applications exposed to very high temperatures. Tungsten is used at lower temperatures for applications that can use its high elastic modulus, density, or shielding characteristics to advantage. Production Tungsten and tungsten alloys can be pressed and sintered into bars and subsequently fabricated into wrought bar, sheet, or wire. Many tungsten products are intricate and require machining or molding and sintering to near-net shape and cannot be fabricated from standard mill products. Shortly before World War II, an easily machinable, relatively ductile family of tungsten-base materials containing a relatively soft and ductile binder phase was developed. These materials, commonly called tungsten heavy metals, are a classic example of the application of liquid-phase sintering to the production of P/M parts. In this case, the basic metal is tungsten, nd the liquid phase in which tungsten is partly soluble is primarily nickel. In the original heavy-metal alloys, it was found that the addition of copper was desirable because it lowered the melting temperature of the liquid phase, thereby lowering the sintering temperature. The resulting tungsten-nickel-copper alloy had good mechanical properties, fair ductility, and good machinability. Subsequently, tungsten-nickel-iron alloys that had greater ductility than the tungsten-nickel-copper materials were developed. It was also found that the tungsten-nickel-iron alloys with higher percentages of tungsten could be sintered to near-theoretical density, thereby producing materials of even higher specific gravity. Tungsten Tungsten mill products can be divided into three distinct groups on the basis of recrystallization behavior. The first group consists of EB-melted, zone-refined, or arc-melted unalloyed tungsten; other very pure forms of unalloyed tungsten; or tungsten alloyed with rhenium or molybdenum. These materials exhibit equiaxed grain structures upon primary recrystallization. The recrystallization temperature and grain size both decrease with increasing deformation. The second group, consisting of commercial grade or undoped P/M tungsten, demonstrates the sensitivity of tungsten to purity. Like the first group, these materials exhibit equiaxed grain structures (Fig. 23), but their recrystallization temperatures are higher than those of the first-group materials. Also, these materials do not necessarily exhibit decreases in recrystallization temperature and grain size with increasing deformation. In EB-melted tungsten wire, the recrystallization temperature can be 900 °C (1650 °F) or lower, whereas in commercially pure (undoped) tungsten it can be as high as 1205 to 1400 °C (2200 to 2550 °F). Fig. 23 Recrystallized microstructure of undoped tungsten wire The third group of materials consists of AKS-doped tungsten (that is, tungsten doped with aluminum-potassium-silicon), doped tungsten alloyed with rhenium, and undoped tungsten alloyed with more than 1% ThO 2 . These materials are characterized by higher recrystallization temperatures (>1800 °C, or 3270 °F) and unique recrystallized grain structures (Fig. 24). The structure of heavily drawn wire or rolled sheet consists of very long interlocking grains. This structure is most readily found in AKS-doped tungsten or in doped tungsten alloyed with 1 to 5% Re. The potassium dopant is spread out in the direction of rolling or drawing; when heated, it volatilizes into a linear array of submicron-size bubbles. These bubbles pin grain boundaries in the manner of a dispersion of second-phase particles. As the rows of bubbles become finer and longer with increasing deformation, the recrystallization temperature rises, and the interlocking structure becomes more pronounced. A comparative impurity analysis of the three grades of tungsten is given in Table 22. Higher concentrations of rhenium (7 to 10%) destroy this effect. In W-2ThO 2 , the occurrence of this elongated, interlocking structure depends on the thermomechanical treatment and on the fineness of the thoria dispersion. Addition of 1.5% or more ThO 2 raises the recrystallization temperature of tungsten in much the same way as the potassium dopant raises it, but ThO 2 additions generally result in a much finer grain structure. Rhenium in amounts up to about 5% inhibits recrystallization; in greater amounts, it lowers resistance to recrystallization. Table 22 Typical purity of the three commercial grades of tungsten Concentration, ppm, in tungsten Impurity element Electron beam zone refined Undoped Doped Iron 1 10 11 Nickel 2 5 5 Silicon 5 21 47 Aluminum <2 <5 15 Potassium <1 12 91 Oxygen 10 27 36 Carbon 20 31 24 Fig. 24 Recrystallized microstructure of doped tungsten wire Tungsten Alloys Three tungsten alloys are produced commercially: tungsten-ThO 2 , tungsten-molybdenum, and tungsten-rhenium. The W- ThO 2 alloy contains a dispersed second phase of 1 to 2% thoria. The thoria dispersion enhances thermionic electron emission, which in turn improves the starting characteristics of gas tungsten arc welding electrodes. It also increases the efficiency of electron discharge tubes and imparts creep strength to wire at temperatures above one-half the absolute melting point of tungsten. A flow diagram outlining the processing of tungsten ore concentrate into major products is shown in Fig. 25. Tungsten mill products, sheet, bar, and wire are all produced via powder metallurgy. These products are available in either commercially pure (undoped) tungsten or commercially doped (AKS-doped) tungsten. These additives improve the recrystallization and creep properties of tungsten, which are especially important when tungsten is used for incandescent lamp filaments. Wrought P/M stock can be zone refined by EB melting to produce single crystals that are higher in purity than the commercially pure product. Electron beam zone-melted tungsten single crystals are of commercial interest for applications requiring single crystals with very high electrical resistance ratios. Fig. 25 Processing sequence for tungsten from ore to finished products Processes for Manufacturing Tungsten Heavy-Metal Alloys. Heavy-metal alloys usually are produced from a mixture of elemental, high-purity, fine-particle-size metal powders. The tungsten powder has an average particle size of about 2 to 3 μm (80 to 120 μin.) and is 99.99% pure. Fine high-purity nickel powder (such as carbonyl nickel), fine electrolytic copper powder, and fine high-purity iron powder (such as carbonyl iron) are used. The powders are blended in a powder blender or ball mill for sufficient time to produce a homogeneous mixture and to achieve an apparent density compatible with the molding operation. If molding is by isostatic pressing, no binder is required. If molding is by pressing in a steel or carbide die in a hydraulic or mechanical press, the powder is coated with paraffin or another suitable organic binder. Molding pressures of about 70 to 140 MPa (10 to 20 ksi) are used. The molded compact must be designed to allow for considerable shrinkage during the sintering operation, usually of the order of 20% lineal or more than 50% by volume. Because of the high shrinkage, most parts produced from these alloys require finish machining if close dimensional tolerances are required. Sintering. The molded parts are usually sintered in box-type electric sintering furnaces by stoking. The furnaces must have molybdenum or tungsten heating elements because sintering temperatures range from about 1425 to 1650 °C (2600 to 3000 °F), depending on the exact composition of the alloy. In some instances, vacuum furnaces are used for sintering these materials, but normally the operation utilizes dry hydrogen or dissociated ammonia for the sintering atmosphere. Sintering times at temperature range from about 20 min for small parts to several hours for large blanks. Part weights can range from a few grams to 20 kg (45 lb) or more. During sintering, rapid densification of the compact occurs as the fine tungsten particles dissolve in the liquid phase and then reprecipitate on the larger tungsten particles. The compact shrinks in this process, and a very dense structure is produced with rounded tungsten-rich grains that are considerably greater in diameter than the original tungsten particles. The blanks are cooled to room temperature in the cooling chamber of the furnace and then removed. Tensile bars and other test blanks usually are sintered from each powder mix and tested for mechanical and physical properties before the mix is approved for production. Hot Pressing. Some vary large parts are produced by hot pressing rather than by cold pressing and sintering. Hot pressing usually is done by leveling the powder mix in a graphite mold and heating the mold in an induction coil while light pressure sufficient to compact the mix to the required density at temperatures similar to those for sintering is applied to the assembly. Hot-pressed compacts of this type usually are more brittle and lower in strength than the cold- pressed and sintered materials. Also, the graphite mold may cause a carburized layer to form on the surface of the blank that is difficult to remove in machining. Coatings Some promising systems for protecting tungsten from atmospheric exposure at temperatures from 1650 to 2205 °C (3000 to 4000 °F) have been developed, including: • Roll cladding with tantalum-hafnium alloys • Slurry-type coatings of iridium-base alloys such as Ir-30Rh • Duplex and triplex silicide- base coating systems that combine slurry, slip, chemical vapor deposition, and pack cementation processes Corrosion and Chemical Resistance At room temperature, tungsten is generally resistant to most chemicals, but it can be easily dissolved with a solution of nitric and hydrofluoric acids. At higher temperatures, tungsten becomes more prone to attack. At about 250 °C (480 °F), it reacts rapidly with phosphoric acid and chlorine. It begins to oxidize readily at 500 °C (930 °F); at 1000 °C (1830 °F), tungsten reacts with many gases, including water vapor, iodine, bromine, and carbon monoxide. Above 1000 °C (1830 °F), tungsten begins to form compounds with various metals. Mechanical and Physical Properties Undoped Tungsten and Tungsten Alloys. Tungsten has high tensile strength and good creep resistance. At temperatures above 2205 °C (4000 °F), tungsten has twice the tensile strength of the strongest tantalum alloys and is only 10% denser. However, its high density, poor low-temperature ductility, and strong reactivity in air limit its usefulness. Maximum service temperatures for tungsten range from 1925 to 2480 °C (3500 to 4500 °F), but surface protection is required for use in air at these temperatures. Wrought tungsten (as-cold worked) has high strength, strongly directional mechanical properties, and some room- temperature toughness. However, recrystallization occurs rapidly above 1370 °C (2500 °F) and produces a grain structure that is crack sensitive at all temperatures. Mechanical property data for unalloyed tungsten and tungsten-molybdenum and tungsten-rhenium alloys are shown in Fig. 26, 27, 28, 29, 30, 31. Additional information on the properties of undoped tungsten is available in the section "Tungsten" in the article "Properties of Pure Metals" in this Volume. Fig. 26 Recrystallization behavior of undoped tungsten bar Fig. 27 Thermal conductivity of undoped tungsten Fig. 28 Creep curves for coiled tungsten wires at 2500 °C (4530 °F) Fig. 29 Room-temperature ductility of annealed wire for five tungsten-rhenium alloys Fig. 30 Effect of tungsten content on the room-temperature mechanical properties of tungsten- molybdenum alloys Fig. 31 Short-time tensile strengths of five tungsten-rhenium alloys Recrystallized tungsten undergoes a ductile-to-brittle transition above 205 °C (40 °F). Only by heavy warm or cold working is the DBTT lowered to below room temperature (Fig. 32). Annealing raises the DBTT of cold-worked tungsten until it approaches that of recrystallized material. Fig. 32 Variation of DBTT with annealing temperature for undoped tungsten. Data are for 10- min recovery annealing of heavily worked 0.75 mm (0.030 in.) diam wire. The exact ductile-to-brittle transition temperature is influenced by many factors, including grain size, strain rate, and impurity levels. The DBTT decreases with grain size unless the grains are larger than 1 mm (0.04 in.) in diameter. The DBTT also drops with increases in strain rate, but it climbs rapidly as impurity levels increase. Like all brittle metals, tungsten is very notch sensitive. Therefore, removal of even minute surface flaws by grinding, oxidizing, or electrolytic polishing prior to service improves ductility and lowers the DBTT. Alloying can have a beneficial effect on the DBTT; the effect of rhenium in producing a ductile alloy is the best-known example. Doping with AKS dopant or alloying with a dispersion of thoria retards recrystallization, thereby improving the [...]... compares past and predicted average annual demands for titanium ingot, castings, and mill products Table 1 Past and predicted average annual U.S demand for titanium and titanium alloys Product form Demand, kg × 1000 (lb × 1000) 1 984 -1 988 44, 182 (85 ,600) (97,200) 20,630 23,273 26,545 (45, 387 ) (51,200) ( 58, 400) 392 727 1,455 (86 2) Castings 38, 909 (76,196) Mill products 1994-1999 34,635 Ingot 1 989 -1993 (1,600)... 4 983 , 4 984 , 4 986 , 4 987 4921, 4924, 4926, 49 28, 4930, 4965, 4967, 49704972, 4974, 4975, 49774 981 , 4995, 4996 Welding wire, 4951, 4953, 49544956; Other, 4959 and 4 982 49414944 Flash-welded ring extrusions, 4933-4936 Bolts and screws, 7640; Spring wire, 4959; and rings in listings for extrusions and bars American Society for Testing and Materials (ASTM) B 265 B 381 and F 620 Bar and billet, B 3 48, F 67... prEN2525prEN25 28 prEN2520, prEN2522, prEN2524, prEN2531 prEN25 18, prEN2519, prEN2521, prEN2530, prEN2532prEN2534 Deutsche Industrie Normen (DIN) standards (Germany) DIN 1 786 0, V LN 65039, and LN 9293 DIN 1 786 4, V LN 65040 DIN 1 786 2, V LN 65040 Wire, DIN 1 786 3 Bolts, LN 65047, Joining elements, LN 65072 French AIR 9 182 (sheet) AIR 9 183 AIR 9 183 Bolts and screws, AIR 9 184 ; British Standards Institution... billet, B 3 48, F 67 B 337 and B 3 38 Nuts, F 467; Bolts, F 4 68; Surgical implants, F 67, F 136 and F 620 American SAE (see also AMS listings)(a) MAM 2242 MAM 2241, MAM 2245 MAM 2245 Shapes, MAM 2245 Military MIL-T-9046 MIL-T-24 585 , MIL-T-9047, MIL-F -83 142 (premium quality forgings) MIL-T-9047 MIL-T24 585 (rod), MIL-R81 588 (welding rod and wire) MIL-T -81 556 (aircraft quality bar and shape extrusions)... mechanical and physical properties of tungsten heavy metal alloys according to these class and type divisions Table 23 Classification of tungsten heavy-metal alloys by composition, density, and hardness Class Tungsten content, % Density Hardness, HRC g/cm3 Type classification(a) lb/in.3 1 89 -91 16 .85 -17.25 0.609-0.633 30-36 I 1 89 -91 16 .85 -17.25 0.609-0.623 32 max II, III 2 91-94 17.15-17 .85 0.620-0.645... "Forming of Titanium and Titanium Alloys" and "Superplastic Sheet Forming" in Forming and Forging, Volume 14 of ASM Handbook, formerly 9th Edition Metals Handbook Recycling of Titanium Scrap As the titanium industry has matured, the use of recycled material has increased In recent years even machine turnings and chips have been approved for recycling, and U.S titanium producers used nearly 18 million kg (40... Tricot, and G Beranger, Ed., Societe Francaise de Metallurgie, 1 988 , p 913 18 P.-J Winkler, Recent Advances in Superplasticity and Superplastic Forming of Titanium Alloys, in Proceedings of the Sixth World Conference on Titanium, P Lacombe, R Tricot, and G Beranger, Ed., Societe Francaise de Metallurgie, 1 988 , p 1135 19 E Tuegel, M.O Pruitt, and L.D Hefti, SPF/DB Takes Off, Adv Mater Process., July 1 989 ,... include propeller and rudder shafts, thruster pumps, lifeboat parts, deep-sea pressure hulls, and submarine components (Ref 7) More information on titanium in marine applications is available in the article "Marine Corrosion" in Corrosion, Volume 13 of ASM Handbook, formerly 9th Edition Metals Handbook Energy Production and Storage Titanium plate-type heat exchangers, condensers, and piping and tubing are... thermal expansion × μm/m °C Magnetic properties g/cm3 lb/in.3 MPa ksi MPa ksi 17.0 0.614 785 114 605 88 4 27 205 30 275 40 5.5 3.1 Virtually nonmagnetic Class 1 17.0 0.614 89 5 130 615 89 16 27 260 38 275 40 5.4 3.0 Slightly magnetic Class 3 18. 0 0.650 925 134 655 95 6 29 350 51 310 45 5.3 2.9 Slightly magnetic Class 4 18. 5 0.667 795 115 690 100 3 32 450 65 345 50 5.0 2 .8 Slightly magnetic · μin./in °F... 390540 57 78 20 BS 25-35t/in.2 0.0125 0.20 382 530 5577 285 41 22 JIS Class 3 0.015 0.30 0.07 0.30 480 617 7090 343(b) 50(b) 18 JIS Class 1 ASTM grade (UNS R50250) ASTM grade (UNS R50400) 1 2 ASTM grade (UNS R50500) 3 0.10 (c) 0.35 0.05 0.30 440 64 377520 55-75 18 ASTM grade (UNS R50700) 4 0.10 (c) 0.40 0.05 0.50 550 80 480 70 20 0.10 0.013 0.25 0.06 0.30 460590 6 785 323 47 18 0.10 . 543 0.415 225 80 0 1470 523 0.433 226 1000 183 0 5 18 0.440 2 28 1205 2200 500 0.432 216 2500 4530 484 0. 481 233 (a) Product of specific resistance and temperature. tungsten-base alloys usually divide them into four classes based on composition (Table 23) and three types based on tensile properties (Table 24). Tables 25 and 26 give typical mechanical and physical properties. classification (a) 1 89 -91 16 .85 -17.25 0.609-0.633 30-36 I 1 89 -91 16 .85 -17.25 0.609-0.623 32 max II, III 2 91-94 17.15-17 .85 0.620-0.645 33 max II, III 3 94-96 17.75- 18. 35 0.641-0.663