An orthotropic flow rule for superplastic Ti-6A1-4V

Abstract During uniaxial testing of rolled Ti-6Al-4V in the superplastic regime, the initially round cross sections of the test specimens became oval. The relationship between this macroscopic anisotropy and the microstructure was modeled by assuming that the lateral flow during uniaxial tests depends on the α phase grain shape in the lateral plane but is independent of the directional grain size parallel to the axis of deformation. With this assumption, the behavior can be generalized to determine the full, multiaxial compliance in terms of the α grain shape. Therefore, with no additional requirements for material testing and only one additional material parameter, uniaxial superplastic constitutive relations can be extended to estimate anisotropic flow.