Microstructures and mechanical properties of hot-pack rolled Ti-43Al-9V-Y alloy sheet

Ti-43Al-9V-Y alloy sheets with dimensions of 300 mm×100 mm×(1.5-2) mm were produced by hot-pack rolling. After rolling, the microstructure of Ti-43Al-9V-Y alloy sheet becomes near gamma(NG), which is comprised of γ+B2 phases. After heat treatment(HT) at 1 200-1 320 °C for 30 min followed by furnace cooling(FC), network shape structure of B2 phases in as-rolled microstructure is retained on the whole. Moreover, with increasing the HT temperature, precipitation of B2 phase lamellae in equiaxed γ grains is increased. Equiaxed γ grains transform partly to α₂/γ/B2 lamellar structure after the heat treatment at 1 320 °C for 30 min. Tensile test results show that room-temperature yield strength(YS) and ultimate tensile strength(UTS) of the as-rolled material are 509 and 612 MPa, respectively. With the test temperature increasing, the YS and UTS of the as-rolled are decreased, but the elongation is improved. After HT at 1 200 °C, both yield strength and fracture strength of Ti-43Al-9V-Y alloy sheet are the lowest. With HT temperature increasing, fracture strength is increased obviously, but yield strength of the sheet after HT at 1 280 °C is the highest, about 869 MPa.