Hydrogen-induced hot workability in Ti-6Al-4V alloy
(1.黑龙江省哈尔滨市哈尔滨工业大学材料科学与工程学院
2.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
2.School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: The effect of hydrogen on hot deformability of Ti-6Al-4V alloy was investigated by isothermal hot compression test with temperature of 800 ℃ and velocity of 0.1 mm/s. By optical microscopy (OM) and transmission electron microscopy (TEM), the influence of hydrogen on the microstructural features was systematically examined including the morphology of α grain, volume fraction of α phase and dynamic recrystallization (DRX). The flow stress shows an initial decrease but a later increase with the increase of hydrogen content. The minimum of peak compression flow stress is obtained when 0.2% hydrogen is added into the alloy. The hydrogen-induced softening of Ti-6Al-4V alloy may be that hydrogen induces the increase of proportion of soft b phase, the increase of DRX and the increase of extent of twins.
Key words: Ti-6Al-4V alloy; hydrogen; flow stress; hot workability; microstructural evolution