High temperature creep behavior of hydrogenated Ti-6Al-4V alloy

Abstract

The thermal creep forming and thermo-hydrogen processing of titanium alloys have been used in industry production. The combination of these methods is a potential way to improve the plasticity of titanium alloys and the formability of complex components. The effect of hydrogen addition on high temperature creep behavior of Ti-6Al-4V alloy was investigated by creep tests and microstructural observations. The results show that β/α phase ratio increases with hydrogen content while α′ and αʺ martensites continuously precipitate in β phase. The α/β or α/α phase boundaries become wider. Hydrogen can promote creep rate through softening effect during primary and steady creep stage. However, the embrittlement happens in the tertiary creep stage. The hydrogenated alloy is more sensitive to initial stress and creep temperature. The creep strain of hydrogenated alloy with 0.2 wt%H is similar to that of as-received one. Meanwhile, the creep strain of hydrogenated alloy with 0.4 wt%H significantly decreases. Besides, the smaller initial stress is beneficial to obtain the larger creep strain.