WORKING AND HEAT TREATMENT OF ALPHA+BETA TYPE TITANIUM ALLOY

摘要

PURPOSE:To manufacture a Ti alloy having a fine isometric alpha+beta two-phase structure and suitable for superplastic working by working and heat treating an alpha+beta type Ti alloy under specified conditions. CONSTITUTION:An alpha+beta type Ti alloy typified by Ti-6Al-4V as stock is subjected to =50% compressive working at a temp. above 1,000 deg.C as the beta-transformation point of the alloy, heated to a temp. in the alpha+beta temp. range and rolled at =20% draft. The alloy is then heated to the beta-transformation point - (the beta-transformation point + 70 deg.C), held in the temp. range for 30sec-30min and cooled to =500 deg.C at =5 deg.C/sec cooling rate. It is further subjected to =50% working in the temp. range of (the beta-transformation point - 400 deg.C) - (the beta-transformation point - 200 deg.C), heated to 700-800 deg.C and annealed for 30-120min. An alpha+beta type Ti alloy having fine isometric grains and capable of undergoing superplastic working is obtd.