SHORT-TERM AND STRESS-RUPTURE STRENGTH OF A BETA-ALLOY OF THE Ti-Mo-Cr-Fe-Al SYSTEM AT HIGH TEMPERATURES,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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To clarify whether it was possible to use a titanium beta-alloy Ti, 7 percent, Mo, 5.5 percent, Cr, 3 percent, Fe, 3 percent A1 quenched from 800 C 1 hr in water and aged at 550 and 525 C for 15 hr modes 1 and 2, 500 C for 20 hr mode 3, 450 C for 50 hr mode 4 with subseuent air cooling at elevated temperatures, as well as to make a comparative evaluation of these modes of aging, the high-temperature resistance of the metal was studied by the centrifugal bending method. Mode 1 proved to be most effective. A study was also made of the alloy properties at temperatures from 20 to 700 C. Of the two aging modes 1 and 2, the former resulted better mechanical properties. The alloy aged at 550 C, for 15 hr may be used as a high-temperature resistant material to 450 C since at these temperatures the alloy keeps the same strength value 130-127 kpmm with a plasticity of 6 to 8 percent. In stress-rupture strength tests at 350,400, and 500 C it was found that by selecting the modes of mechanicothermal treatment, for the purpose of giving the beta-grains a polygonal structure which leads to more uniform distribution of the separated alpha-phase along the dislocation walls, high heat-resistant properties may be obtained in the alloy.
- Metallurgy and Metallography