Development of a Thermomechanical Model for Prediction of Residual Stress during Laser Powder-Bed Fusion: Evaluation of Inherent Strain Approach

Abstract

The build-up of residual stresses in a part during laser powder-bed fusion (LPBF) provides a significant limitation to the adoption of this process. These residual stresses may cause a part to fail during a build or fall outside the specified tolerances after fabrication. Defectfree production of metallic parts using LPBF requires process optimization, as a crucial step, for effective usage of the process. Development of a numerical model to accurately predict the induced residual stresses and distortion during the LPBF process is of great interest as it allows to effectively investigate the influence of processing parameters on the quality of the parts. In this work, we developed a novel high-fidelity finite element (FE) model based on the inherent strain (local-global) approach to simulate the build process and calculate the residual stress and distortion for Hastelloy X specimens built with a continuous scan strategy. Conclusions from the thermomechanical simulations showed good agreement with X-ray diffraction measurements and 3D scanning data used to determine the residual stresses and distortions in the parts.

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