Abstract
The effects of short-time 2-stage induction heat treatment on the microstructure and mechanical properties of Ti-6Al-4V alloy were investigated. After the alloy was solution-treated at temperatures in the α+β field (1243 K) and in the β field (1373 K) for 60 s and was water-quenched, it was aged at 773 K for 40 s, 0.6 ks and 1.8 ks. Through the above 2-stage heat treatment, the β-phase was transformed to an α′ martensite phase possessing a high hardness, and then fine a α-phase was precipitated in the α′-phase. With this change in the microstructure, the 0.2% proof stress and tensile strength were remarkably improved while the reduction of area was decreased. The decrease of the ductility was especially significant in the alloy solution-treated at 1373 K above β transus and aged. In all of the examined conditions, the appropriate heat treatment was the treatment consisting of solution treatment at 1243 K for 60 s and aging at 773 K for 40 s. This heat treatment increased the 0.2% proof stress and tensile strength by 33% and 31%, respectively, for a short time and held the reduction of area at 17%.
