Ti-6Al-4V 合金の二相組織における変形挙動の結晶塑性解析

Vanadium contents in the β phase in the Ti-6Al-4V alloy (Ti-64) changes by the heat treatment, plastic working, and so on, and its mechanical properties are also changed; it would affect the deformation mechanisms of microstructures in Ti-64; however, it is not fully understood. In this study, a sandwiched microstructure of α and β phases, where the crystal orientations satisfied Burgers orientation relation, was assumed, and the uniaxial tensile analysis was conducted using a crystal plasticity finite element method (CPFEM). The results showed that the elastic constants of the β phase was higher than that of α phase when the vanadium content of the β phase was high and the tensile direction corresponded to the direction perpendicular to the c-axis; it resulted in higher stress within the β phase in the range of elastic deformation. In contrast, there was a possibility that such relationship of stresses between α and β phases was not established by conditions in the range of plastic deformation.