Mechanical properties of fully martensite microstructure in Ti-6Al-4V alloy transformed from refined beta grains obtained by rapid heat treatment (RHT)

Fully martensite microstructures transformed from refined beta grains were obtained in a Ti-6A1-4V alloy by rapid heat treatment (RHT) into a single beta phase region followed by water quenching. Ultrafine-grained equiaxed alpha + beta microstructure obtained by hot compression of martensite was used as the starting microstructure for subsequent RHT. By increasing the heating rate from 10 degrees C/s to 50 degrees C/s, the resulting beta grain size was refined from 40 mu m to 8 mu m, which was the smallest size of beta reported so far. Both strength and ductility increased with decreasing the beta grain size, which was attributed to the reduced micro-crack lengths by fractography analysis. (C) 2017 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.