DEPARTMENT OF DEFENSE TITANIUM SHEET-ROLLING PROGRAM, THERMAL STABILITY OF THE TITANIUM SHEET-ROLLING-PROGRAM ALLOYS
An experimental program was conducted to evaluate the stability of the mechanical properties of heattreated Ti-6A1-4V, Ti-4A1-3Mo-lV, and Ti-16V-2.5A1 sheet alloys during thermal exposures under stress. Triplicate specimens of each alloy, whose initial properties were satisfactory in comparison with SheetRolling Program (SRP) target properties, were exposed under stress calculated to produce creep strains in the range of 0.1 to 0.5 per cent at temperatures of 100 and 1000 hours at each temperature. The thermal exposures showed Ti-6Al-4V and Ti-4A1-3Mo- lV alloys to have comparable creep strengths above 600 F, considerably better than those of the Ti-16V-2.5Al ing the the exposures showed that Ti-6A1-4V exhibited a slight trend toward instability at 900 F for 1000 hours, but the degree of instability was not sufficient to warrant concern. The TI-4A1-3Mo-lV alloy showed indications of overaging during 1000-hour exposure at 900 F, but otherwise exhibited good thermal stability. The overaged properties shown were still within the MAB target properties for the DOP-SRP alloys. The Ti-16V-2.5A1 alloy showed some instabtiity under all exposure conditions. Tensile ductility after both exposure times at 500, 600, and 700 F, and after 100 hours at 800 F was below target, and both the yield and ultimate strength values were below target minimum after the 900 F, 1000-hour exposure. After exposure of 100 hours at 900 F, the properties of Ti-16V-2.5A1 were satisfactory in reference to target, but the evidence from the other exposure conditions indicates that the alloy under this condition are already passed through the aging peak, and is in the overaging cycle. (auth)
- Research Organization:
- Battelle Memorial Inst. Defense Metals Information Center, Columbus, Ohio
- NSA Number:
- NSA-13-003810
- OSTI ID:
- 4287556
- Report Number(s):
- DMIC-46E; AD-205778; PB-151061
- Country of Publication:
- United States
- Language:
- English
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