Metastable beta Sheet Alloy Ti-8MO-8V-2FE-3AL, Part I

摘要

A 500-lb. ingot of metastable beta alloy Ti-8Mo-8V-2Fe-3Al was melted and mill processed to plate and sheet for evaluation. No processing problems were encountered. Plate samples were evaluated in 2 in and 1/2 in sections; room temp. and 600F smooth and notched tensile properties and K sub ic values were obtained. Samples taken from both sections of plate, when solution treated and aged for 16 hrs. at 900F, had room temp. yield strengths of 190-200Kpsi; K sub ic values were 45-48Kpsi-square root of (in). Sheets of 0.040 and 0.060 in gage were evaluated by determining 50 and 100% recrystallization parameters, using mill annealed sheet and hot rolled sheet given 25 and 50% cold reduction. Aging response of these materials was then determined at 800-1200F and tensile properties evaluated after selected treatments. From this, 8 conditions of heat treatment were selected for further evaluation by sub-zero and 600F smooth and notched tensile, bend, notched fatigue and K sub ic tests, measurement of creep stability; stress corrosion resistance and oxidation characteristics; and study of welding behavior. Ti-8Mo-8V-2Fe-3Al possessed good notch tensile strength over the range of -65 to 600F; the notched fatigue limit, with a notch configuration of Kt = 3.5, was 30-35Kpsi, and the plane strain crack propagation resistance was 45-60Kpsi-square root of (in). Creep curves were obtained, employing loads of 90% of the yield strength at 600F, for exposure times of 500 hrs. (Author)