Titanium Past, Present, and Future (1983) / Chapter Skim
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Chapter 11: Technologic Opportunities for Titanium
Chapter 11: Technologic Opportunities for Titanium
Pages 153-162
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From page 153... ...
Other practices that may become available in the future appear to be those that give improved economy in the production of titanium and provide improved properties by way of refining microstructures. This chapter considers those processes that the panel believes are most likely to attain significant industrial importance in the not too distant future (5 to 10 years)
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From page 154... ...
Yttrium and Rare Earth Additions In 1974, the RMI Company pioneered the pilot production of titanium alloys containing 0.005 to 0.03 weight percent yttrium that refined the microstructure and significantly improved the yield of salable mill products from ingots. Because of the reluctance among certain users to accept yttrium additions in titanium, production was discontinued.
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From page 155... ...
Proces sing The high cost of titanium and its alloys is due primarily to three f actors: high sponge cost; relatively poor yield f ram sponge to mill products, particularly for high-strength alloys; and large secondary fabrication losses, especially in military and commercial aerospace applicat ions . The average ratio of buy weight to fly weight for aircraft applications is estimated to be about 6 :1; some individual parts achieve a low 1.5:1 ratio whereas others approach 20:1.
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From page 156... ...
Superplastic and Diffusion Bonding Fine-grained titanium alloys are superplastic at low strain rates within critical temperature ranges, generally near the beta transus where deformation occurs primarily by grain boundary shearing. It probably is not coincidental that alloys can be diffusion bonded under the same time-temperature conditions.
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From page 157... ...
Isothermal shape rolling also might be expected to be used more commonly f or gaining similar economic advantages in cases where rolled shape s can be applied in volume . Precision Casting The precision casting of complex titanium shapes has progressed rapidly during the past decade, particularly when the castings are subsequently hot isostatically pressed to close internal porosity.
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From page 158... ...
When hot isostatically pressed, the properties of both precision-cast and precision-molded parts approach (their proponents maintain that they can equal and occasionally even exceed ~ wro ught properties. Unalloyed titanium powder, blended with master alloy part icles, is a possible lower cost alternative to alloy spheres, particularly for some applications.
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From page 159... ...
The near-net-shape route to mill products was to be used to achieve the cost reduction du Pont felt was necessary for titanium to become an important metal to the process industries. This large effort failed because of a single, unanticipated technical problem that has been kept as a trade secret until released by du Pont for this NMAB report.
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From page 160... ...
This led to the panel' s recommendation that an appropriate government agency (perhaps the Air Force) sponsor a detailed study to calculate both the energy consumption and the complete manufacturing costs of mill products by conventional ingot metallurgy and to compare these data with those of tonnage powder metallurgy mill products using an assumed reasonable cost for tonnage powder (e.g., 100, 200, and 400 percent of sponge cost)
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From page 161... ...
161 REFERENCE Tanner, L
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