Analytical investigation of residual stress in samples with variable cross-sectional surfaces in the laser powder bed fusion process

Abstract

One of the primary challenges associated with the laser powder bed fusion process is the presence of residual stress. These residual stresses arise from the significant thermal gradients induced by the rapid heating and cooling of the material, which are inherent to the laser powder bed fusion process. Such stresses can contribute to crack formation, distortion, and, ultimately, failure of the component. Consequently, effective control of residual stress is of paramount importance. In this study, an analytical approach was employed to establish the relationship between the distribution of residual stresses within samples exhibiting two variable cross-sectional geometries. Utilizing the principles of force and moment equilibrium, the distribution of residual stresses in each layer of the sample was determined. To validate the analytical method, experimental measurements of residual stresses in both the surface layer and the interlayer region of Inconel 625 samples were conducted. Additionally, the impact of hatch distance on the residual stress within the experimental samples was examined. Residual stress measurements were performed using a non-destructive X-ray diffraction technique. The results from the experimental analysis indicate that an increase in hatch distance correlates with a reduction in residual stress. Furthermore, a comparison between the residual stress at the center of the surface layer and that at the interface of the variable cross-sectional sample reveals that the residual stress at the interface is approximately halved.