Phase Transformations and their Effects on Hardness in Ti-6Al-4V Alloy

Abstract

The phase transformations and their effects on hardness in Ti-6Al-4V during solution treatment and aging were investigated using the α and β alloys containing the same amounts of Al and V in the α and β phases which are in equilibrium in Ti-6Al-4V at temperatures from 770 to 1000°C. In Ti-6Al-4V solution treated at 750°C, a small amount of the β phase is retained and the existence of the β phase causes remarkable softening of the alloy. For the examination of the aging process of the alloy, considerations should be given not only to the phase transformations in the α and the β grains present at the solution treatment temperatures but also to those in the vicinity of the interface between α and β which arise from the movement of the interface and the migration of solutes. The latter transformations exert a remarkable influence on the hardness of the alloy.