Thermo mechanical Finite Element Analysis of the plasma Wire Arc Additive Manufacturing process in DEFORM® 13

Abstract

This study investigates the potential of Finite Element Analysis in DEFORM® to predict the thermal history, deformation, residual stress state and grain growth in the Wire Arc Additive Manufacturing processes of Ti–6Al–4V. The temperature dependent material model for Ti–6Al–4V was extended and adapted to improve the representation of contact boundary conditions within DEFORM®, focusing on Additive Manufacturing. A single layer quad-mesh approach was employed alongside dummy heat sources to simulate the process by accurate layer wise activation within the arc welding module. The model utilized a normalized double-ellipsoid heat source and introduced a power adaptation strategy to account for differences in volumetric deposition. The extracted thermal history showed very good agreement to corresponding thermocouple measurements. The accuracy of the resulting deformation state was validated using a 3D scan, while the predicted grain size distribution was compared against an as-built micrograph. The simulation showed good overall accuracy, though limitations were noted in the grain size model, which was inadequate in predicting the more complex texture of the mixed $\alpha /\beta$-microstructure typical for Ti–6Al–4V. Seven heat treatment strategies were evaluated to address mechanical anisotropy. Solution annealing followed by water quenching and subsequent low temperature aging was found to be most effective.