Effect of texture on the room temperature tensile and creep properties of Ti–6Al–4V plate with large thickness

Abstract

Texture is inevitably generated during the rolling process of titanium alloys, which has a significant impact on mechanical properties. The relationship between microstructure, texture and mechanical properties of the rolled Ti–6Al–4V alloy plate with large thickness was systematically investigated in this study. The texture type varied with the thickness of the plate. The basal pole concentrated in the transverse direction (TD) at the surface of the plate and tilted from TD towards the rolling direction (RD) at the quarter thickness of the plate. For the center of the plate, the basal pole had peaks concentrated close to both TD and RD. Tensile tests indicated that TD samples not only have high strength but also maintain good plasticity compared with RD and the normal direction (ND) samples. The yield anisotropy could be explained by the difficulty of prismatic and basal dislocation slip. The cold creep behavior of the thick plate depended on both Schmid factor of dislocation slip and grain size. Moreover, the strain hardening exponent was positively correlated with cold creep strain. Abundant prismatic <a> and pyramidal <c+a> dislocations were activated, and slip transfer and cross-slip made the dislocation slip distance longer, which contributed to creep strain and thus reduced the creep resistance of ND sample.