Predicting the complete tensile properties of additively manufactured Ti-6Al-4V by integrating three-dimensional microstructure statistics with a crystal plasticity model

Abstract

A multiscale finite element model integrating microstructure statistics with an enhanced three-dimensional (3D) crystal plasticity model including damage has been developed to predict the complete tensile stress-strain response of Ti-6Al-4V manufactured by selective laser melting. A statistically equivalent representative volume element (SERVE) was constructed from an orthogonal set of electron backscatter diffraction (EBSD) images capturing key statistical information such as the spatial distribution of the grain size and the crystallographic and morphological orientation of the grains. Working from this 3D SERVE as a statistical model of the real microstructure, the crystal plasticity finite element (CP-FE) method was then used to predict the complete tensile stress-strain response of the material, including damage post necking. For the first time, crack-band theory (CBT) was incorporated into the CP-FF model to accurately predict ductility and to minimize mesh size sensitivity, which is a common issue in existing models. The effects of the 3D SERVE size on the stress-strain response was investigated through a rigorous sensitivity analysis. The model was calibrated using one sample and validated against a second sample with a different microstructure and properties. The new multiscale model provides a basis for a comprehensive Integrated Computational Materials Engineering (ICME) tool to enable the rational design of new high-performance materials.