Effect of Retained β Phase on Mechanical Properties of Cast Ti-6Al-4V Alloy

Abstract

We investigated effect of retained β phase on mechanical properties of cast Ti-6Al-4V alloy, after solution treatment and subsequent aging for a short time. The alloy was solution-treated at 1123, 1223 K in the α + β phase region and 1323 K in the β phase region for 1800 s, followed by water quenching. After that, as-quenched specimens were aged at 823 K for 300 s. The peak hardness of heat-treated specimens was obtained by solution treatment at each solution temperature and followed by aging at 823 K for 300 s. It was due to ne α phase transformed from the retained β phase. The tensile strength of specimen as-quenched at 1223 K and subsequent aged at 823 K for 300 s was increased, without signi cantly decreased ductility. This was due to the ne α phase transformed from the retained β phase by subsequent aging for 300 s. This behavior of increased strength without dramatically decreased ductility might be caused by the transformation induced plasticity (TRIP) effect, which is the strain-induced martensite transformation from the retained β phase throughout deformation, even after aging at 823 K for 300 s.