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Chap ter 6 U. S . NATIONAL TITANIUM STOCKPILE Sponge titanium metal can be the key bottleneck in the production of finished titanium components; therefore, titanium sponge stockpiling has been a prime component in the U.S. government's defense strategy and in its support of the industry. Since there are important dif ferences in the chemistry and melting characteristics of titanium sponge produced by the various manufacturers, specif ications for purchases of sponge for the U.S. National Defense Stockpile (the term U.S. National Stockpile is used interchangably) could determine whether a particular manufacturer's sponge would be acceptable for the stockpile. Closely related to this is whether improved and new sponge capacity to satisfy the specifications would be encouraged by the prospect of sales to the stockpile. All titanium stockpile purchases to date have been of sponge. Since ingots and mill products, both commercially pure and alloy , are closer to final end uses, an important question is whether the U.S. National Defense Stockpile should include ingots and mill products and, if so, what specifications should apply. The primary purpose of the titanium stockpile is to have sufficient quantities of adequate-quality titanium sponge immediately available for defense use in time of national emergency (if a stockpile is strictly limited to national emergency use, it is termed a "strategic stockpile" ). A secondary purpose has been to use stockpiling as one of the government's measures to support the domestic titanium industry, (particularly, via its purchases, to encourage expansion of sponge manufacturing capacity). Finally, there is always considerable support to use the U.S. National Stockpile to absorb surplus production during periods of low demand and to alleviate shortages during high demand periods (a so-called "economic stockpiled. For the reasons presented in Chapter 12, this panel recommends that the U.S. National Stockpile for titanium be kept strategic in character. The U.S. National Stockpile contains 21,465 short tons of sponge titanium metal meeting the specifications in force when it was purchased. In addition to this material, the stockpile contains 10,866 short tons of non-stockpile-grade sponge titanium. The amount of specif~cation-grade material now held is considerably short of the recently established goal for stockpiled sponge titanium of 195,OOO short tons (FEMA May 1980~. This shortfall in specification-grade titanium sponge in the national stockpile places the United States in a vulnerable position. The DoD is reviewing the situation and the Air Force has taken steps in an attempt to remedy it (Appendix D ~ . 59
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60 The constructive aspect of this vulnerability, however, is that it gives the government the opportunity to use the buildup of the stockpile to further o ther national goals . Table 6 shows the GSA titanium disposal actions since 1960. Among these might be the production of higher quality. sponge fully usable by all domestic melters. Another would be to replace a substantial proportion of or substantially augment the s tockpile sponge goal with ingot and even selected mill product s. In this manner, U. S . fabricators would have a head start towards producing end products for their ultimate use in a national emergency. The panel believes that it does not have sufficient expertise to make recommendations on these important matters. However, it believes it can note in this report the perceived options available to the government and leave it to other, perhaps ad hoc, groups to gather data and consider all the facts bef ore developing such recommendations. There is good agreement among stockpile observers that specification-grade titanium sponge is the only desirable type to be carried in inventory. As noted in Chapter 5 and Appendix H' U.S. National Stockpile Purchase Specification P-97-R6 covers titanium metal sponge and ASTM B-299 is the applicable public specifications An important question is whether or not these specifications are adequate to serve the best interests of the nation. TABLE 6 GSA titanium stockpile disposal actionsa Year 1960 19 63 1964 19 65 196 6 1967 196 8 19 69 197 0 1971 19 74 b 197 5 Amount - 17 67 35 117 495 902 113 6 711 51 8, 392 918 Total Sol d 11~844 a Sales authorized under the Defense Production Act (DPA). b Sales of materials in excess of new goals set by the Federal Preparedness Agency (now FEMA). Source: Private communication to the committee by GSA.
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61 In view of the foregoing considerations, it would appear that the administration of the stockpile must identify the most probable scenarios under which the stockpile will be used and then base decisions on stockpile sponge quality on those scenarios. A key question is whether, in the national emergency envisioned, the high-volatile-content sponge manufacturers would be able to continue in full production or would lose some of their sponge-making capacity. In the latter case, they could not employ their full melting capacity without securing outside sponge. At present, the U.S. sponge producers maintain a good balance between their sponge (plus scrap and alloy additions) and melting capacities. If their sponge-making capacity were unimpaired during the hypothetical emergency, they would not need to use any sponge from the stockpile. The nonintegrated melters (almost one-third of U . S. melting capacity), on the other hand, would need the stockpile sponge and would much prefer the low-volatile grades. Thus, in such a si tuation, the stockpile sponge presently held would not be needed by the integrated melters and could not be used readily by the nonintegrated melters. Minkler (1979) has pointed out that if, among other incentives, there were renewed U.S. stockpile contracts, investments in new greenfield t itanium winning plants would produce low-volatile sponge f ully competitive in quality with the Japanese and Soviet product s . The government 's option of specifying a certain percentage of low-volatile (Type MD-120) sponge for the stockpile therefore would have the desirable effect of motivating the existing domestic producers to build greenfield plants capable of producing competitive-quality sponge and of ensuring that a portion of the stockpile sponge could be processed readily by all melters. Again, as noted earlier, the panel is making no firm recommendation on this matter other than to suggest the establishment of an ad hoc panel or panels to study these stockpile matters in detail and then to formulate recommendations. In any case, existing U.S. sponge manufacturers still could participate in the stockpile buildup if the government simultaneously decided, that ingots and mill products should constitute a substantial proportion, such as half, of the stockpile since the quality of titanium mill products is unaffected by the volatiles content of sponge that has been vacuum melted. In addition to the inventory of titanium sponge grades stockpiled, suggestions have been made for stockpiling consolidated titanium (from sponge). Both ingot and primary fabricated forms might be considered. If ingot and fabricated forms were included, some of the metal should be in alloyed grades rather than unalloyed. Since Ti-6Al-4V alloy is the most used titanium material (even exceeding the use of unalloyed titanium), it would appear appropriate to include ingot and fabricated forms of this material in the stockpile. The grades of Ti-6Al-4V alloy selected for inventory should be based on a study of grades that are judged to be most useful for critical applications. It is anticipated that rotating-grade or premium-grade will be most appropriate (e.g., for gas turbine engine use ~ .
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62 Other titanium alloys also might be considered for the inventory. Suggested alloys include Ti-6Al-2Sn-4Zr-6Mo, Ti-17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr), Ti-6Al-2Sn-4Zr-2Mo, and Ti-lOV-2Fe-3Al. For other titanium materials needed to optimize the stockpile content, the selection of various alloys and grades of alloys should be based on research to determine the most useful materials. Consolidated forms of titanium alloys that might be considered for stockpiling probably should be confined to ingot, billet, and bar. Ingot definitely should be considered since all other mill product forms stem from this precursor. Billet also might be considered because the availability of "off-the-shelf" billet during a national emergency would save considerable time in the production-of-parts cycle. Further, billet also is a precursor for a wide variety of other mill product forms as well as for forgings directly. Bar might be stockpiled in the sizes amenable to gas turbine engine parts (including compressor blades) since it is certain that bar stock would be used in large quantities for blade manufacturing and quite possibly for other uses under a variety of crisis scenarios. Specifications for titanium-base ingots, mill products, and alloying additions are discussed in the final section of Chapter 7. It is noted that, although there are no public specifications for titanium alloy ingots, the specifications for mill product quality requirements indirectly control the quality of ingots. For example, ingots for the manufacture of quality mill products are prepared to two principal, widely recognized, quality categories: standard quality and premium quality. These quality measures generally also apply to the mill product produced by ingot fabrication (e.g., bloom, billet, bar, plate, sheet); therefore, the starting material, the ingot, must have an equivalent quality. Suitable controls are described f or the preparation of ingot for premium material in the Society of Automative Engineers (SAE) and ARrospace Material Specification (AXIS) 2380, Approval and Control of Premium Quality Titanium Alloys. The same specifications used in defining such products as billet and bar could be applied to def ine ingot quality for stockpile purposes. Specifications such as ASTM B348 and MIL-T-9047G as well as AVIS 2380 would be useful in off Bring quality guidelines for ingot, billet, and bar stock. This aspect of stockpile guidance should be based also on the results of studies to determine the most appropriate action. All these inputs could best be integrated by a separate ad hoc titanium specif ications panel. REFERENCES FEMA press release, May 1980. Minkler, W. W., 1981. NMAB-381, Pp . 65-73 . Assessment of Selected Materials Issues, National Academy of Science, Washington, D .C.