Prediction of residual stress and deformation based on the temperature distribution in 3D-printed parts

Abstract

Selective laser melting (SLM) is a promising additive manufacturing (AM) technique that has the potential to produce almost any three-dimensional (3D) metallic parts with complicated structures. During the SLM process, the thermal behavior of metal powder plays a significant role in maintaining the product quality during 3D printing. Furthermore, due to high heating and cooling rates within the selective laser melting (SLM) process, a high-temperature gradient forms in the heat-affected zone, which generates significant residual stresses within the fabricated parts. In this study, a thermo-mechanical coupling model was developed for studying thermal behavior, residual stress, and deformation during the SLM process of Ti6Al4V alloy. In the experiments, a TELOPS FAST-IR (M350) thermal imager was applied to determine the temperature profile of the melting pool and powder bed along the scanning direction during the SLM fabrication using Ti6Al4V powder. The numerically calculated results were compared with the experimentally determined temperature distribution. The comparison showed that the calculated peak temperature for single track by the developed thermal model was in good agreement with the experiment results. Through the simulation, an effective prediction method for investigating the effects of process parameters such as the laser power and scanning speed on the temperature distribution, residual stress, and deformation was established. The findings showed that the development of residual stress on the fabricated parts gradually increased throughout the SLM process, produced by a heat accumulation effect.