Numerical Simulation of the Effects of Preheating on Electron Beam Additive Manufactured Ti-6Al-4V Build Plate

Abstract

In an earlier study, a 3-D thermomechanical coupled finite element model was built and experimentally validated to investigate the evolution of the thermal residual stresses and distortions in electron beam additive manufactured Ti-6Al-4V build plates. In this study, an investigation using this robust and accurate model was focused on an efficient preheating method, in which the electron beam quickly scanned across the substrate to preheat the build plate prior to the deposition. Various preheat times, beam powers, scan rates, scanning paths and cooling times (between the end of current preheat scan/deposition layer and the beginning of the next preheat scan/deposition layer) were examined, and the maximum distortion along the centerline of the substrate and the maximum longitudinal residual stress along the normal direction on the middle cross-section of the build plate were quantitatively compared. The results show that increasing preheat times and beam powers could effectively reduce both distortion and residual stress for multiple layers/passes components.