Anisotropy of Mechanical Properties in Ti-6Al-4V Hot Rolled Plates

Abstract

When the α+β type titanium alloys are not subjected to the proper hot rolling process, the anisotropy in the microstructure appears even after the solution treatment and aging. This study was conducted to examine the anisotropy in mechanical properties of two heats (A and B) of Ti-6Al-4V alloy hot rolled plates which are subjected to the solution treatment and aging, and the mechanical anisotropy was correlated with the microstructural anisotropy. Tensile properties shows isotropic nature for both alloys. K_Ic and K_Iscc of alloy A are slightly reduced for transverse direction. On the other hand, K_Ic of alloy B is not reduced in T direction and K_Iscc is markedly increased for T direction. The K_Iscc in T direction is higher than K_Ic in the same direction. It was found that stress corrosion cracking of alloy B in transverse direction which was formed at the tip of prefatigue crack propagated with some branching along the primary α phase boundaries, leading to the apparent increase in K_Iscc.