Constitutive relationship and fracture mechanism for wide stress triaxiality of titanium alloy

Abstract

It is necessary to determine the fracture criteria and parameters that conform to the plastic deformation and fracture mechanism of titanium alloy under wide stress triaxility. Fourteen different shapes and notch specimens were designed for uniaxial tensile and compression experiments. Based on the analysis of plastic behavior and fracture mechanism, the Swift-Voce hardening model, CPB06 yield criterion and DF2016 fracture criterion were respectively established. The fracture parameters of the ductile fracture model were calculated by the analytic equation solving method. The fracture behavior of forged TC4 titanium alloy was successfully predicted by finite element software. The research results showed that the dimples of fracture morphology become larger and deeper with the increase of stress triaxiality, and the ductile fracture mechanism changes from shear fracture to dimple fracture mechanism. The comparison of experiment and simulation indicated that the Swift-Voce hardening model and CPB06 yield criterion reasonably simulate the plastic deformation. It also proved the DF2016 model can provide the most accurate prediction of fracture behavior for forged TC4 alloy under different stress states.