Influence of heat treatment on microstructure and microhardness of titanium Grade 4 subjected to HPT

Abstract

In this work, the influence of severe plastic deformation by torsion (HPT) and subsequent heat treatment on the microstructure and microhardness of commercially pure titanium Grade 4 is considered. It is determined that after HPT a homogeneous ultrafine-grained (UFG) structure with a high dislocation density is formed and, as a consequence, a significant increase in microhardness up to 353 ± 7 HV is observed. Subsequent annealing at 700 ?C activates the processes of relaxation and grain growth, which leads to a decrease in microhardness. It was found that the HPT treatment at a temperature of 300 ?C allows obtaining the maximum value of microhardness – 426 ± 10 HV.