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Chapter 9 END USES OF TITANIUM "Light, strong, ductile, and corrosion-resistant" were the features that sold titanium offered from the beginning. "Light and strong" meant a higher strength-to-weight rat to than that possessed by aluminum and steel up to 550°C. "Ductile" implied formability and toughness. "Corrosion resistance" signified maintenance-free aircraft even on seawater-drenched carriers. Thus, in the early 1950s, the newborn jet aircraft industry and titanium seemed made for each other. Starting in the 1960s, industrial uses of titanium began to become significant. During the 1970s, commercial and military aerospace uses continued to increase, although erratically; industrial applications grew steadily and in 1980 amounted to one-fourth of total titanium shipments. A number of large-potential industrial uses have emerged, and it appears possible that one or more of them could grow in the next decade or two to rival the still-growing uses of titanium in the aerospace industry. Reason for Titanium Use The element titanium in bulk metallic form is a relatively low-strength plastic solid of intermediate density that is extremely reactive chemically. However, the metal has an adherent, nonporous, chemically-inert oxide skin that makes titanium one of the most corrosion-resistant of the structural metals. Titanium also has low thermal and electrical conductivity and a weak paramagnetic response. The usefulness of titanium as an engineering material is related to its uniquely desirable combination of chemical, physical, and mechanical properties and to the ability to prepare high-strength, tough, and ductile alloys from the base material. Materials of low to moderate and high strength result f ram the alloying of titanium with elements such as aluminum, tin, oxygen, iron, vanadium, chromic, and molybdenum . The ductility and toughness of such alloys are commensurate with the strength levels attained and are quite satisfactory for most engineering purposes. Properties are maintainable over a wide temperature range. The materials are very competitive with other engineering materials when compared on a strength~density basi s . Figure 12 shows comparative tensile strength density data over a range of temperatures. In addition to desirable combinations of mechanical properties, titanium and its alloys are quite corrosion resistant in most common environments and even in some that very aggressively attack most other 101
102 1~2 1.' t.O 0.9 O 0.8 C O 07 lo 0.6 AS - ~ O.C' ._ C 0~3 Oi! 0~1 o _ ~~~ I , · . . . lly~hBOl-~.O:~d . - ` AL ti'cn;um belo sIto' lidiesteel _ _ ~4340 {mod)_ 1 ~Y\YPH ~toinlesS 1 1 1 he . ~ -a.-~ ~e _,. .~ I._ . _ I ~c~-loo o.umlnum cloy- 0 400 800 1200 Temperoture, OF ~ 1 _ Figure 12 Comparison of tensile stength~density ratio f or titanium alloys, three classes of steel, and 2024-T86 aluminum alloy. - engineering metals. This resistance to chemical attack is maintained to moderately high temperatures. Oxidation reactions in titanium are insignificant in terms of consuming or embrittling the bulk material over the pref erred range of temperatures where the useful strength of titanium i ~ to be maintained . titanium are bulk
103 There are additional good reasons for using titanium. For example, its modulus of elasticity is intermediate between that of aluminum and steel, which permits good structural compatibility in mixed metal structures. Further, the modulus-to-dens~ty ratio is quite high compared t o that of some other structural materials and that permits an economy in minimum weight designs. Figure 13 shows comparative modulus density ratio data over a range of temperatures. The fatigue and creep strengths of titanium alloys also are excellent (Figures 14 and IS). In addition, the thermal stability of selected titanium alloys in preferred heat-treated conditions is outstanding, and the the low thermal-expansion characters attics of titanium per Wit dimensionally stable structures. 1 Ti-8Al- loo- 1V 2 PH 14-8 Mo Steel 80 60 0 100 300 500 Temperature, 'F Figure 13 Materials stiffness efficiency after 24,000 hours temperature. Source Fa~rbairn 196 4. 1 3 T~-6A1-4V 4 2219 Al 700 900
u) 104 120 100 ~0 - 60 20 , ~ ,~ r-6Al-6v-2S~ [RsO.I] >\~\ 7;-6~1-~ \ .'. ~ ` ~(nougat `~~ \ · T-sA1-2.ssn Ronge. for (moth) [R: -I ~ ~[R ~ O." to - rt-S&~-2.SSn 1 - tt~et, ~t ~ 4) [R: -13 80. 10' 60' 10' Life cycle Figure 14 Typical room temperature fatigue characteristics of selected titanium alloys. Source: Wood 197 S. Titanium materials are forged to shape readily and are fabricated to end items using common metalworking techniques. Several commonly used grades (e.g., grades of unalloyed titanium and the Tz-5Al-2.5Sn, Tz-6A1 - V, and Ti-3Al-2. 5V alloys) are fusion~eldable via all of the ~ nert-gas-shield~ng techniques. Most of the alloys are heat-treatable to a rave of strength levels. Machini sag and finishing procedures have been d eveloped into routine operations. Although this description of titanium' s attributes is not exhaustive, it can be clearly recognized that there are many reasons f or selecting titanium as the material of choice for d~scr~m~nat~ng applications. The following sections provide some insight regarding where titanium and its alloys have f ound greatest use and where the use of this material might be extended in the years ahead.
105 104 100 30 80 70 60 SO ~0 ~0 20 Temperoture, °F \ \ \ \ \ ~ \ ~\0.2% Ti- 661- 4V (STA)\0 2 °;O f ~ T'-641- 2Sr.- aZr - 6Mo (STAN ~ ~. .2% Ti- 641 - 6V- 2 Sn (574: 10 ~ 2S 27 29 3 1 ,;~Ti;SAI- 6Sn- Ear- I Mo- 0.255i , \ ~ `` Rupture ' " \ 0 2 % \0.2 °/O ~ \ ~ \ \ Ti - 6AI - 2Sn- ~ 2r - 2Mo (STA)\ \ ~ STA = solution treated and aged 33 35 Lorson-Miller Porometcr, P: ~ (20 ~ 1o; I) 1 000 Figure 15 Typical creep and stress rupture behavior of selected titanium alloys.
106 Use History The impetus for the birth of the titanium industry was provided by military planners who believed that titanium would fill several of their material needs. Those needs were related to the development of the gas turbine engine for aircraft propulsion and the development of lightweight armor and ordnance; the corrosion resistance needed of materials for the saltwater environment also were influential. Ordnance hardware (e.g., mortar base plates and artillery flash suppressors) were among the earliest titanium applications. By 1955, about 90 percent of the titanium production was used in building aircraft and engines (Table 14~. TABLE 14 Use Distribution of Titanium in 1955 ~ _ _ _. Percent of Total Mill Products Use Category Source Ad Source B ~ Military aircraft gas turbine engines 47.1 Military airframes 36.2 F~ It tary nonaircraf t uses 10.4 Commercial airframes 6.1 Industrial (corrosion resistant) uses 0.2 a Goodwin 1956. b Jaffee 1962. 60 33 4 3 Between 1955 and 1960, a dramatic 50 percent drop in titanium production and use resulted from the shift in military planning from a strategy involving manned aircraf t to one with reliance on unmanned missiles. This dip is reflected in mill product shipments shown in Figure 16. This figure shows the predominance of titanium use by the aircraft industry over all of the early history. The detailed use data over a 12-year period are given in Table 15. Data by major titanium use category over the most recent decade of titanium's history (1971-1981) are plotted in Figure 17 (the same data are plotted separately in Figure 1~. Although these data do not present a detailed picture, they clearly show that the aerospace industry still consumes over about three-quarters of all the titanium mill products shipped. The steady growth in consumption by the nonaerospace markets for titanium is of particular interest.
107 S per 1b 28 K 41 C ° 11 o C 8 l. CJ :' o - - - : ~_ Million lbs \ ~_ ~n_ts · a° C~ 30 U~ t10 ~ - . - I'tS 1~" "~, l~d I'AS I't. Figure 16 Titanium industry market prof ile (based on 1968 data) TABLE 15 Utilization of Titanium 1961-1973 . Use Wood datal Aircraf t Jaffee dataE Percent _ _ 1971E 1973 Mi litary engines 37 32 20 14 Airf rames 26 25 10 20 Subrotal 63 57 30 34 Commercial engines 10 13 31 23 Airf rames 4 7 15 17 Subrotal 14 20 46 b'O TOTAL 77 77 76 74 Other Mi ssles and space 16 15 Helicopters and ordnance Industrial uses 7 1 1 16 18 ~_ 7 TOTAL 23 23 24 26 a Wood 1975 b Jaffee 1962.
108 ~1 ~1 ~1 AS a:- o ~ 25 - 20 - - t~ 10 ~1 OF , ~ .98tE^~d l\ J a''t=~ - ce - - ~ Indu~rial Me^-ts , ~. t t ~t ~ ~ I ~ t I l 7D 72 74 ?. 78 ~ at Yeer Figure 17 Titanium industry market pro f lie based on 1980 Data. Source: Minkler 1980. Overall, of the total quantity of mill products ~ 2 81, 000 tons ~ shipped in this period, over 220,000 tons (or nearly 78 percent) of total shipments have been utilized by the aerospace industry. Industrial uses, primarily for corrosion-resistant applications, have taken over 33,000 tons (between 11 and 12 percent), and over 22,000 tons (nearly 8 percent) have been applied to other nonaerospace uses. Aerospace Appl ications Ga ~ Turbine Engine s The Pratt & Wh! tney (P&W) J-57 gas turbine engine was one of the first important applications for titanium. Some of the early versions of this engine, applied to such military aircraft as the B-52 and the KC-135, flew with only 10 pounds of titanium . A later version of the J-57 contained 7 percent of the engine weight in titanium components (about 260 lbs) for the low-pressure compressor stages (discs and blades only). Advanced versions of the J-57 engine (e.g., J57-P-43W) were constructed with more than twice that amount of titanium (15.6 percent,
109 586 lbs) . In that engine, the inlet case and the front compressor case were constructed of unalloyed titanium. Ti-6Al-4V alloy was uled for front and rear compressor blades, the front compressor discs, hubs, spacers, and some of the rear compressor discs and spacers. Gas turbine engines for commercial aircraft began in a similar way. The first engine models did not contain titanium (e.g., the P&W JT3A, JT3C6, and JT3C7 for the Boeing 707 and 720, and the Douglas DC-8 contained no titanium) . Advanced versions of the JT3 engine, the JT3D-1 and -3, and later the JT4A-5 (for later models of the Boeing 707 and Douglas DC-8) and the JT8D-1 engine (for the Boeing 727 and Douglas DC-9) each contained several hundred lbs of titanium, principally unalloyed and Ti-6Al-4V alloy (Table 16) e TABLE 16 Titanium Use in Pratt & Whitney Gas Turbine Engines For Commercial Airliners Components JT3D-1 JT8D-1 Ti wt. Stage Material Ti wt. Stage Material ~ lb) Inle t case 91 - cpa 64 - cpa Compressor (alloyb) Vanes 72 1 alloyb 45 1 alloyb Discs and hubs 174 1-9 alloy 96 1,2,4-6 alloy Spacers and seals 23 1,2,4 alloy 21 1,2,4-6 alloy Blades 205 1-9 alloy 125 1-9,12 alloy To tal 565C 351i a Commercially pure unalloyed titanium. b Principally Ti-6Al-4V alloy. c Equals 13.8 percent of the total engine weight of 4, 090 d Equals 11.6 percent of total engine weight of 3,024 Ibs. The General Electric ~ GE ~ Company, who also pioneered in the development of aircraf t gas turbine engines and the use of titanium to reduce engine weight, introduced a modest amount of titanium in its J-79 engine and increasing amounts in engines of later design. This increasing use of titanium in GE engines f ram the mid-1950s to the mid-1960s is shown in Table 17. A large proportion of engine weight in the TF39, a high-bypass turbofan engine, was of titanium.
110 TABLE 17 Evolution of Materials Use in General Electric Gas Turbine Engines Percent of Material Usage . Engine Year Aircraf t Composites Al/Mg Titanium Steels Superalloys J47 19 45 J79 1955 J93 1960 GE4 19 65 TF39 1965 Ne xt g enera t ion F-86, B-47 0 F-104, B-58, F-4 XB-70 SST C5A o o 2 5-10 Source: Simmons and Wagner 1970 22 3 0 70 8 2 85 10 1 7 24 68 1 12 15 72 1 32 18 4 7 1 25 15 50 The engines for commercial aircraft, the GE CF6 core engines, and the P&W JT9D engine series also are of the front-fan, high-bypass-ratio type and contain large quantities of titanium. Simmons and Wagner (1970) discuss the development of the front-fan engine in terms of titanium utilizat ion as f allows: The large high-bypass turbofan engines could not have been developed without strong lightweight titanium alloys. The percentage of titanium alloy in the TF39 engine for the C5A has reached 32 percent of the total metals weight in the engine. This may be the high point for titanium usage in jet engines, because two factors will work to reduce the application of titanium. The f irst is the use of composites, which is just beginning. Large fan part s that now account for most of the titanium alloy usage can probably be made largely of composites. The second factor is the increased temperature in the compressors of supersonic engines, which has a [ready necessitated the replacement of several t itanium s sages in the hot end by parts made of a nickel-base alloy. However, new manufacturing techniques may result in lighter hollow titanium fan and compressor blades that could make it quite difficult for composites to replace them. Ti-6Al-4V alloy has been the high-volume alloy in gas-turbine engine applications, with some Ti-8Al-lMo-lV and Ti-5A1-2 . 5Sn alloys being used . It i s expected that 'ri-6Al-2Sn-4Zr-2Mo and Ti-6Al-6V-2Sn alloys will reach high-volume usage in advanced engines. Tables 18 and 19 list titanium use in a typical modern fan-jet engine by component and alloy.
111 TABLE 18 Titanium Use by Component in a Typical Modern Fan-Jet Engine ~_~ Part Material . Alternate Ti Alloy a Alternate Material a Inlet case 5Al-2.5Sn Tib, 8Al-lMo-lV 12Cr "stainless" steel Fan blades 8Al-lMo-lV 6A1-4V, 6Al-6V-2Sn CompositesC Fan disks 8Al-lMo-lV 6A1-4V, 6Al-6V-2Sn, Low-alloy steel' 12Cr Ti 67 9 steel Fan exi t struts 6A1-4V Tit, SA1-2. 5Sn 12Cr steel Fan duct Ti, 5A1-2. 5Sn 8Al-lMo-lV A1 alloy Fan duc t f airings Tib 5A1-2. 5Sn A1 alloy Front camp. blades 8Al-lMo-lV 6A1-4V, 6Al-6V-2Sn 12Cr s teel Front camp. disks 8Al-lMo-lV 6A1-4V, 6Al-6V-2Sn Low~alloy steel, 12Cr steel case Rear camp. blades c Front camp. case 6A1-4V 5A1-2 . SSn, 8Al-lMo-lV 12 Cr s teel Interned . 5A1-2. 5Sn 8Al-lMo-lV 8Al-lMo-lV 12Cr steel 6A1-4V, 6Al-2Mo-4Zr-2Sn, 12Cr steel, Ni alloy Ti 67 9 Depending on temperature, stress, corrosive resistance, cost, and we ight requirement s . b Commercially pure titanium A-55 or A-70 grade. Such as graphite f iber-reinforced epoxy and boron-reinforced aluminum. Source: Simmons and Wagner 1970. Small gas turbine engines also used titanium. The weight incorporated into the designs of these smaller engines was not remarkable . However, in several instances, production runs for the smaller engines were substantial and accounted f or an appreciable consumption of titanium . Engines produced by such companies as AiResearch (e.g., models TPE-331, T-76, and TFE-731) and Lycoming (eege, model T53-L-13) were important for their use of titanium. A list of representative gas turbine engines that collectively utilized large quantities of titanium is given in Table 20. Where the information is available, the approximate purchase weights of the titanium required to make the parts that ultimately fly in the engine are given as are representative airframe model numbers that utilized the engine models listed. Note that the
112 data are given for a single engine unit whereas several of the aircraft in which the listed engines were used were multi-engine aircraft. Further, the production runs of engines for aircraft include a number of spare engines; 25 percent spares is a quantity of ten cited. TABLE 19 Titanium Alloy Utilization for a Typical Modern Fan Jet-Engine - Alloy Form Finished - - ~ part weight weight (Ib) (lb) Raw Material Percent Used finished/raw Wt. Ti Sheet 142.2210.0 67.7 Bar and forging27.8299.4 9.3 5Al-2.5Sn Sheet 121.2256.8 47.2 Bar 5.364.7 8.2 Forging 183.62366.4 7.8 6A1-4V Bar and f orging223 . 81544. 0 14. 5 Al-lMo-lV Bar 2.015.3 13.1 Forging 238.01152.8 20.6 . Total 944.35909.4 16.0 Source: Simmons and Wagner 1970 Airf rame s The quantities of titanium used in constructing airframes for both the military and commercial sectors of the aerospace industry have been quite large. The amount of titanium used in airframes generally is lower in any given year than that used in engines (e.g., see Tables 14 and 15) although for some aircraft more titanium is used in the airframe than in the engines. Some of the early 1950s aircraft with titanium in their airframes used only small quantities. Aircraft in subsequent years not only became faster and more sophisticated but also much larger in order to accommodate larger payloads. The larger aircraf t utilized more titanium as is shown in Table 21. The form of titanium used and the alloy mix employed in the construction of airframes varies widely with vehicle requirements as might be expected. For example, the Boeing 747 reportedly uses over 16,000 lbs of forgings, mostly Ti-6Al-4V and some Ti-6Al-6V-2Sn; over 5,000 lbs of extrusions; about 3,000 lbs of plate; and 2,000 lbs of fasteners and ducting. The Lockheed L-1011 uses 14,200 lbs of forgings and castings; 6,000 lbs of sheet; 5,900 lbs of bars, tubes, and extrusions; 2,200 lbs of ducting and fittings; and about 3,100 lbs of fasteners. The alloys and fly weights utilized in the L-1011 airframe are presented in Table 22.
- 113 TABLE 20 Estimated Purchase and Fly Weights of Titanium Components in Aircraf t Gas Turbine Engines Estimated Weight, lb EnginePurchase Weight Fly Weight Airframe J52-P-61300 300 A-4E/F/M J52-P-8A1400 300+ A-6A/B/E J79-8600 125 F-4J/M J7 9-15500 100 RF-4C/D/E TF3 ~P-64500 850 A-7A TF30-P-3/84500 850 F-lllA/B, F-14A TF41-A-11200 285 A-7D/E J584000 800 YF-12A TF3 3-P-74250 637 C-141A TF3 3-P-53800 565 C-13 SB J75-P-19W4500 677 F-105 TF-398000-9000 2 ~ 00 C5A T-7 6150 25 OV-1OA TF-341200 - A-1OA J85500 60 F-5,T-38A FI00/401 5SOO - F-15, F-16 J101 1400 - F-18 F101 4500 - B-1 T-64 800 - CH-53E T-7 01/700 1000 - - JT9D 12000 1200-2300 B-7 47 CFt3-50 8000 700-1300 DC-10 RB-211 5500 - L-1011 GE-4 - 1000 B-2707 (SST) Source: Simmons and Wagner 1970, and Wood and Barr 1974. Use of titanium in military airframes (e.g., in the F-14, F-15, and B-1 aircraft) is chiefly Ti-6Al-4V alloy; however, lesser amounts of Ti-6Al-6V-2Sn and Ti-3Al-2.5V alloys are also tlsed, the latter for the tubing in the hydraulic systems. The breakdown of mill product f orms f or the F-14 and F-15 (purchase weights) have been estimated to be (all numbers approximate) as shown in Table 23.
t 114 TABLE 21 . Estimated Purchase and Fly Weights of Titanium in Airframes of Commercial Airliners Aircraf t System ~Fly Weight (lb) (lb) Boeing 707500 190 7271,800 750 7373,200 1,100 74732,000 11,000 747SP45,000 12,000 7 57a3 5, 000 9, 500b Mc Donnel 1-I)oug la s DC-9-302,000 600 DC-~-6210,000 2,426 DC-10-3030, 000 8, 100 Lockheed L-101131, 600 14, oooC a b c The weight of the 757 is approximately one-quarter of the f ully loaded weight of the 747. No t f inal as of early 1981. Includes titanium in engines for fly weight (about 6000 lbs), but not for purchase weight. . TABLE 22 Alloys and Fly Weights of Titanium in the L-1011 Alrframe Component s Alloy Fly weight ~(lb) Forgings Ti-6Al-4V, Ti-6Al-6V-2Sn1, 300 Extrusions, sheet, springs Ti-6A1-4V, Ti-13V-llCr-3A13, 600 Fasteners Ti-6Al-4V2, 000 Failsaf e straps Ti-6Al-4V, Ti-6Al-6V-2Sn500 Other systems Ti-6Al-4V, unalloyed Ti1, 200 Source: Data from industry spokesmen.
115 TABLE 23 Mill Product Forms for the F-14 and F-15 (purchase weighta) F-1-4 Form Estimated amount (lb) Forgings22,400 Forgings 29,150 Plate12,000 Plate 11,000 Sheet4, 400 Sheet 5, 200 Bar and tubing1, 200 Extrusions, tubing, and f asteners 11, 350 To tal40, 000 Total 56, 700 Estimated fly Estimated fly weight5,190 weight 6,940 Percent of purchase weight13 Percent of purchase weight 12.1 a Purchase weights are approximate. Source: Wood 1975, Wood and Barr 1974, and data from industry spokesman. The estimated titanium purchase weights for airframe construction for some other military aircraft are listed in Table 24. The fly weights are not as readily available as the purchase weights but, where given, indicate a low utilization ratio. Industry spokesmen have commented on the low utilization ratio in the past as is indicated in the following excerp t f rom Wood ( 1975 ): The large amounts of thick-section mill products used in sophisticated aircraf t such as the F-14 and F-15 lead to low utilization ratios. For example, only about 12 percent of the 56,700 lbs of the titanium purchased flies in the F-15 airframe. Using forgings as an example, forgings of 1,275 and 900 lbs are machined down to 14 5 and 100 lbs f inished part weights, respectively, representing only about 11 percent utilization. Forgings are generally not amenable to a high utilization ratio, since blocker type forgings are usually purchased and because the parts vary in section thickness from point to point. Precision forgings might be ordered for some shapes in the smaller sizes, but they are more expensive than blocker shapes and not available in large sizes.
116 TABLE 24 Estimated Purchase and Fly Weights of Titanium in Military Airf rames Aircraf t System Purchase Weight Fly Weight (lb) (lb) A-411 A-6E A-7E F-4JtM F-5E/F A-1OA F-16 F-18 C-130H B-1 150 600 280 2,800 750 2,600 3,000 6,000 1,000 170,000 50 185 1,200 24, 800 Source: Wood and Barr 1974, and data from industry spokesmen. The possible application of the advanced metallurgical processes for producing near net shapes (eege, isothermal forging, isothermal shape rolling, superplastic forming, superplastic forming with diffusion bonding, and powder metallurgy and metal casting techniques) is believed to offer the means for greatly improving the utilization ratio of titanium in constructing airframes. Wider adaptation of these methods to a large variety of airframe parts could result, as noted in Chapter 11, in a considerable material saving. For an aircraft weapons system such as the B-1, a large vehicle with about 18 percent of its airframe weight in titanium, the raw material savings could be remarkable. Missiles and Space Vehicles Titanium was considered quite early for missiles and other space vehicles. For example, titanium was designed into the Navaho air breathing missile (principally Ti-13Y-llCr-3A1 alloy) and, although this missile never became a production item, the application generated an interest in titanium for use in other systems. Af ter the low production year of 1958, almost 1 million lbs of titanium were incorporated into missiles and space probes in 1959. Almost 2 million lbs of titanium were applied to space vehicles in 1960, a remarkable growth.
117 There are six major applications for titanium in missiles and space vehicles. These are listed in an early 1961 Titanium Metals Corporation (TIMET) brochure as: 1. Cryogenic pressure vessels for liquid-fueled missiles. 2. Storage tanks for cryogenic fuels and structural components of space vehicles designed to operate in the cryogenic temperatures of space. 3. Rocket motor cases f or solid-fueled vehicles. 4. Nozzle exit cones. 5 . Co ntro 1 mechanisms such as servo valves, gyro scopes, gimbal housings, and tubes for communications devices. 6. Miscellaneous components such as interstate structures, adapter rings, and skins. Titanium pressure bottles (Ti-6Al-4V) were outstandingly successful in the Atlas launch vehicle (about 7S lbs finished weight per bottle), in the Agena A satellite, and in the Ablestar spacecraft with a restartable engine. Project Mercury, the first manned spacecraft, utilized titanium panels for the inner shell of the vehicle. This vehicle also used a 205-lb ring in an adapter section of the system. Pressure bottles of titanium were used in the follo~up Apollo program and the associated moon-lander vehicle. In later programs, titanium was selected for the frame of the space telescope. The Space Shuttle vehicle, although not primarily of titanium design, requires 25,000 lbs of titanium raw materials (purchase weight) for each craft. The use of titanium in the transtage section of the Titan II military strategic missile was an important application (components machined from large forgings). The Minuteman II and III missiles' second-stage motor cases were made of Ti-6Al-4V and their production was continued into the 1970s (Model III and a shroud that was retrofitted to Model II vehicles). The purchase weight of titanium for each of the Minuteman III missiles was greater than 7,000 lbs. In addition, titanium was designed into the Po seidon, the Polaris, and into tactical missiles as well. Only small amounts of titanium are used in components for the last group (e.g., in pressure bottles and in turbine wheels) , but in several cases, such missiles were produced in large numbers (e.g., Hawk, Dragon, Lance, TOW, Sparrow, Sidewinder, Phoenix, Maverick, and Harpoon. Non-Aerospace Applications Ordnance The promise and hopes for titanium in ordnance applications were never fulfilled to the degree that was anticipated during the formative years of the industry. There were some limited successful early applications. A mortar base plate and an artillery flash suppressor are examples; however, basically, many of the attempted applications for titanium never
118 matured beyond the developmental stage (e.g., the use of titanium alloy as components of battletank treads and in the suspension system can be cited). Entryport tank hatches also have been made of titanium for ease in operation by one man. In the 1970s, titanium alloy again was examined f or use in the suspension system (torsion bars) of military ground vehicles (Scout, an armored personnel carrier) only to be eliminated in the final material selection process. If helicopters are considered as being within the ordnance category, then titanium can be thought of as winning an important place in ordnance as a preferred material in the construction of its component parts. Some helicopter models require thousands of pounds of purchased titanium; however, titanium use in helicopters generally is included under the aerospace category. It is used principally in engines but also in some parts of the airframe systems. Rotor hubs and blade components are notable examples. Alloyed titanium also has found use as armor plate in helicopters (e.g., more than 1,200 lbs of titanium has been used around crew stations, fuel tanks, and the propulsion system on a single HH53B helicopter). Use of titanium as armor in other instances can be cited. For example, during the Vietnam War, plates of Ti-6Al-4V alloy were loosely attached to the truck-body sides of personnel carriers for protection against small-arms f ire . A bathtub-like enclosure of Ti-6Al-4V plate around the rear and sides of the pilot ' s seat in the A-1OA aircraf t, and in other combat vehicles, represents a present use in the armor category. As another example of the armor application, the Ti-5Al-2.5Sn alloy is used in the "Standard Type A, Hl" body armor vest (6e 5 lbs per vest). Civilian versions of body armor (vests) also use titanium. At one time, titanium was considered for ground troop combat helmets (Ti-5Al-2 . 5Sn) . Implementation of this plan, which required slightly under 2 lbs of titanium per helmet, never materialized. Titanium as a material of construction for weapons has found its greatest application in missiles, as previously described. There were great hopes at one time for titanium in the rocket launcher (tube) of the one man Davy Crockett missile weapon system; however, substantial production of this system never materialized. Titanium also has been examined for use as shell casings for both small arms ammunition and large ammunition. This application would appreciably reduce the carry weight of ammunition. In addition, various titanium applications have been examined wherein the aim was to reduce the carry weight of articles to further the mobility of a modern military force. Support equipment such as water purification units and refrigeration units are in this category. In addition, there are a number of applications for titanium in the field of nuclear armaments. None of these can be considered to be large consumers of titanium and cannot be discussed for. security reasons.
119 In summary, there have been a number of developmental titanium ordnance applications that have not advanced to the status of requiring large quantities of titanium. The largest demand for titanium in the ordnance category has been for missiles and helicopters, both of which usually are classified as aerospace applications. The ordnance category remains ripe with the potential to become a very large market for titanium, but there are no publicly announced systems that suggest fruition in the immediate future. Marine Use s The use of titanium in items encountering a seawater environment has been an area of large titanium consumption. Valves, pumps, and piping for handling seawater on both surface and subsurface ships are the hardware items in greatest demand. The U.S. Navy program for the development of deep diving submersible (DDS) vehicles--for exploration, for rescue, and potentially for weapons systems (limited to research and development to date)--also has produced a steady demand for limited amounts of titanium. The titanium (Ti-6Al-4V) buoyancy spheres and the spherical, thick-wall, pressure hull for the deep submersible Alvin vehicle are the most representative hardware items in the DDS category. The Navy research and development program in the area of DDS technology has resulted in some notable advances in the understanding of titanium metallurgy. The program continues and the Navy is at a point where the technology can be applied to production vehicles on a larger scale. Titanium also has been employed for specific naval ordnance such as torpedoes, mines, and missiles (missiles, however, generally are included in the aerospace category). Unconventional marine vehicles such as hydrofol1 and surface effect vehicles have utilized titanium components but not on a tonnage production basis. GE's LM-2500 gas turbine engine, (a derivative of the CF6 aircraft gas turbine engine), which utilizes about 8,000 lbs (purchased weight) of titanium, powers the Spruance-class destroyers. There are several engines per ship and several ships have been launched. The list of marine uses for titanium generally includes deck fittings and undefined miscellaneous hardware. Buoys also have been constructed with titanium as have various dock-side items that are exposed to the corrosive sea environment . Various marine tools (e. g., underwater salvage tools) are minor users of titanium. Several pieces of equipment f or use on of f-shore working platf arms are of titanium construction but usually are included in the petroleum processing category of industrial uses . The discussion of the marine usage of titanium cannot be concluded wi shout mention of the sporting boat applications. Perhaps the most famous of these has been the titanium mast application (upper one-third) on the America's Cup challenger (and winner), the Intrepid. Titanium was
120 selected f or the s use because of its preferred strength and modulus characteristics, but the consumer market for lesser applications is of more importance in terms of potential future demand for titanium. Items such as propellers ~ shaf ts, collars ~ struts, steady bearings, transom bands, rail and roof stanchions, deck plates and a variety of other deck f ittings, and anchors (Danf orth type) have been produced f ram titanium in the past. A continuing small market for such items is anticipated. Industrial Uses Titanium's growing use in so many applications in several industries requires that for descriptive purposes, the industrial sectors be listed as subcategories. For example, titanium is used in the following industries (the list is not exhaustive): 1. 2. 3. 4. 5. 6. 7. 8. 9. Water purification processing (desalination). 10. Waste processing and disposal. 11. Sports equipment manufacturing. 12. Ground transportation manufacturing. 13. Medical related manufacturing. 14. Miscellaneous manufacturing. Chemical processing. Pulp and paper manufacturing. Textile manufacturing. Mining and minerals processing industry. Me tat processing . Petroleum. Electricity generation and other energy-related f unc Lions. Food and drug manuf ac turi ng . The use of titanium in these industrial subcategories is largely related to its excellent corrosion-resistance characteristics. However, there also are industrial applications that are related to titanium's mechanical and physical properties and frequently to combinations of several of titanium's features. Generic types of equipment (e.g., heat exchangers of many different designs and functions) serve the same basic purpose f ram industry to industry . On the other hand, some types of titanium items have unique functions for particular industrial needs (e.g., low-inertia shuttles in weaving machines). The following list of equipment , more or less using generic terminology ~ illustrates the types of titanium equipment used: 1. P~mps--housings, impellers, shafts. 2. Va~ves--housings, gates, shafts. 3. Vessels--holding tanks, mixing tanks, reaction towers, pressure vessels, dif fuser towers, washing tanks.
121 Vessel internals--rotating and reciprocating agitators, filter elements, supports and screens, diffuser tubes, coils, thermocouple wells, baffle plates, etc. 5. Piping--straight runs, bends and long and short runs of various diameters, fittings, flanges, terminal nozzles and nozzle liners, sparser tubes, expansion loops and coils, etc. 6. Heat exchangers--tube bundles in tube-plate terminations, plate type, bayonet type, tube in shell with coil, helical or hairpin configurations. 7. Driers and concentrators--spray-type driers, high-speed rotating atomizer wheels, centrifuges. 8. Conveyors--housings screw on shaft type and endless belt type, piping for gas or liquid vehicle conveyors. 9. Distillation columns--associated hardware. 10. Fans and shafts--housings. 11. Frames and brackets--clamps and clips, spools, racks and trays, hooks. 12. Fasteners--threaded bolts and nuts, screws, nails, rivets, wrap wire. Corrosion resistance for processing media and reaction products has been mentioned as the dominating reason for the selection of titanium for industrial equipment. Titanium is essentially immune to attack in a variety of media over a considerable temperature range and extended exposure times. Unalloyed titanium is the material of choice due to its lowest cost among titanium materials, easy fabricability including weldability, best corrosion resistance (except for alloys especially formulated for this purpose such as Ti-0.2Pd and Ti-0.8Ni-0.3Mo alloys), acceptable mechanical properties, and ready availability in several product forms. The forms most used are the flat-rolled products and the roll-and-weld tubing that is produced from strip. Some seamless tubing is used. Castings are used extensively (e.g., valve housings) and a few forgings are used. Bar stock and wire use is greater than forging use. Powder metallurgy products are in use (e.g., for controlled porosity and permeability filter elements). Counting the roll-and-weld tubing precursor strip, about seven times as much flat-rolled product is used as other kinds of product. Table 25 shows the percentages of product forms used recently in industrial applications. It is noted that while industrial usage of flat-rolled products is about 86 percent of the total industrial sheet use, flat-rolled products constitute only about 22 percent of the total mill products manufactured. Although an exhaustive list of individual industrial applications would number in the hundreds, and perhaps the thousands, the quantity of titanium required for such applications has not been large except in the past 5 to 10 years. In fact, for the first 20 years of titanium's growth as an industry, only about 10 million lbs of titanium were used in this category. However, the growth of the use of titanium in the nonaerospace category has been remarkable over the past 10 years.
122 TABLE 25 The 1980 Estimated Utilization of Titanium in the Industrial Non-aerospace Sector by Product Form and Approximate Unalloyed Titanium Prices Composite Prices, Estimated dollars per poundb Product Utilization, April April Form percenta 1979 1981 Tube and pipe 53.0 8.7 5 12 . 50C Sheet and strip 19 .0 6.25 10 .50 Plate 14 .2 7.20 10.30 Bar and billet 9.5 7 .90 12 . SO Wire 2.3 14.50 25.00 Castings 2.0 20.00 38.00 a - - Based on the material purchases of one company serving the industrial uses sector. Price varies with quantity purchased, grade, dimensions, surface finish, and other product variables. Mid-1981 price increased to the $14-15/lb range. Although continued growth of titanium use is expected in the industrial use sector, nontechn__al problems possibly could reduce the growth rate of 12 to 13 percent experienced by this sector of the titanium market over the past 10 years. The high cost of titanium products is undoubtedly the leading problem that possibly will inhibit greater use. A second problem is that insufficient application research and market development studies have been conducted for the nonaerospace use of titanium. A third problem, which is somewhat technically oriented, is related to the question of adequate product availability a viewed by the potential user.
123 REFERENCES American Society for Metals. 1961. Metals Handbook, 8th ea., Vol. 1, Properties and Selection of Metals. Metals Park, Ohio: American Society for Metals. Fairbairn, G. A., Structural materials f or supersonic transport. ALLA Paper 64-628 presented at the AIAA Technical Aircraft Design and Operations Meeting, Seattle, Washington, August 1964. Goodwin, H. B., 1956. Titanium today. Paper presented to a Chapter Meeting of the Society for Electrical Engineers. Columbus, Ohio Jaffee, R. I., 1962. Titanium in 1975. Journal of Metals, Vol. 14, Pp 588-589. Materials Advisory Board Titanium Subcommittee of the Committee on Technical Aspects of Critical and Strategic Materials. 1969. Usage of Titanium and Its Compounds, with Comments on Scrap and Sponge. Report MAB-249, Washington, D. C.: National Academy of Sciences. Minkler, W. W., Review of materials availability issues. Paper presented at the special meeting of the National Material s Advisory Board, Washington, D.C., September 3, 1980. Pratt & Whitney Aircraft, Division of United Aircraft Corporation, data sheets; late 1960s. Schapiro, L. and E. Labombard, Nine years of titanium usage. paper presented at the 6th Anglo-American Aeronautical Conference, Folkestone, England, September 10, ~ 957. (Reprinted by the Royal Aeronautical Society in 1959, London, England)., 1957. Simmons , W . F ., and H. J . Wagner 1970. Current and Future Usage of Materials in Aircraft Gas Turbine Engines. Defense Metals and Ceramics Information Center Memorandum 245. Battelle Memorial Laboratories, Columbus, Ohio. Titanium Ingot, Mill Products, and Castings, Current Industrial reports (ITA-991), Bureau of Census, Bureau of Industrial Economics, Office of Basic Industries, U.S. Department of Commerce, Washington, D.C.
124 Wood, R. A., and H. W. Barr, 197 4 . Current Status of the U.S. Titanium Industry, A Special Study for the Office of the Director of Defense Research and Advanced Technology . Metals and Ceramics Inf ormation Center report MCIC CR-74-01. Battelle Memorial Laboratories. Columbus, Ohio. Wood, R. A., 1975. The Titanium Industry in the Mid-1970s , Metals and Ceramic Information Center, Report MCIG-75-26 Battelle Memorial Laboratories, Columbus, Ohio.
