Deformation induced anisotropic responses of Ti–6Al–4V alloy Part II: A strain rate and temperature dependent anisotropic yield criterion

Based on the extensive new experimental results, a yield criterion is proposed to describe the anisotropic yield behavior and tension compression asymmetry characteristics of an electron beam single melt Ti–6Al–4V alloy. In the proposed anisotropic yield criterion, a novel method is introduced to decouple the anisotropy and tension compression asymmetry characteristics; thus the anisotropic coefficients and tension compression asymmetry parameter can be determined independently. The Khan–Huang–Liang (KHL) constitutive model is used as the hardening response of the alloy along different loading directions, and subsequently used to determine the material constants in the proposed yield criterion over wide ranges of strain rate and temperature. Moreover, the newly proposed yield criterion is used to correlate the yield loci of the Ti–6Al–4V alloy at different strain levels, strain rates and temperatures. Good agreements between predicted yield surfaces and corresponding experimental data is obtained. Furthermore, a generalized yield criterion are proposed which can comprehensively predict different types of yield surfaces.