Investigation of Intergranular Fracture Mechanisms During Quasi-Static Tensile Deformation of Tc6 Titanium Alloy Based on 3d Cpfem-Czm Approach

Abstract

To achieve the reconstruction of non-uniform dual-phase microstructures and investigate the mechanism of 3D intergranular fracture, a 3D representative volume element with grain boundaries was modeled by the developed algorithm based on EBSD data of TC6 titanium alloy. The crystal plasticity finite element method (CPFEM) and cohesive zone model (CZM) were employed to describe the mechanical response of different grains and failure behavior of grain boundaries (GBs). Consequently, the accumulated plastic strains and intergranular fracture were well-predicted based on 3D CPFEM-CZM approach, and the simulation results closely matched those from the in situ tensile tests. Furthermore, the influences of GB position (perpendicular or parallel to the loading direction), GB angle and stress-strain level of the grains on the intergranular fracture were further investigated. Meanwhile, the coordinated deformation mechanisms of different grains were further revealed through the relative activity and Schmid factors of the slip systems. Notably, the slip system <11-23>{10-11} was crucial for the coordinated deformation of grains. This work improves the understanding of intergranular mechanical responses and fracture of titanium alloys, and introduces a new methodology for the exploration of the deformation behavior of titanium alloys considering GB properties.

Keywords: titanium alloy, Three-dimensional representative volume element, Cohesive zone model, Intergranular fracture.