A Simplified Methodology for Estimating Residual Stresses in Powder-Bed Electron Beam Additive Manufacturing

Abstract

In regard to the dimensional accuracy of additive manufactured parts, the prediction and control of residual stresses constitute a challenging issue. The objective of this research is to develop a simplified method of estimating residual stresses in powder-bed electron beam additive manufacturing (EBAM). We propose a model in which residual stresses arise from thermal strains during the cooling step, and confirmed the validity of the model by X-ray diffraction using the sin²ψ method and the modified internal residual stress method. The stress distribution of the model showed good agreement with the experiment except in local areas such as the side of the additive layer and the interface with the base plate. We clarified that the residual stresses of manufactured parts in powder-bed EBAM can be mostly estimated by thermal strains induced in the additive layer and the base plate during cooling step.