On the development of part-scale FEM modeling for laser powder bed fusion of AISI 316L stainless steel with experimental verification

In laser powder bed fusion (LPBF), the effects of operating conditions on thermal gradients and residual stresses are the utmost challenges that require significant attention. The magnitudes of residual stress in the printed layers, as well as the distribution along the printed components, have not been well explained for LPBF parts. In this study, a 3D finite element thermo-mechanical model has been established to investigate the effect of operating conditions on thermal distribution, melt pool evolution, residual stress distribution, and part distortion. The printed AISI 316L stainless steel cubes have been characterized experimentally. The results showed a proportional correlation among the number of layers, thermal distribution, and melt pool dimensions. A combination of compressive and tensile stresses was recorded in the LPBF-ed parts. The Cauchy stresses were maximum in magnitude at the bottom and top surfaces along the xx- and yy-orientations, while these stresses increased in magnitude along with the part-build orientation (zz) within the whole printed cube except the top surface. The Von Mises stresses were minimal than Cauchy stresses. A maximum displacement was identified at the printed components' contours, gradually decreasing from top to side walls and top surface. An inverse correlation was identified among average Von Mises stresses (AVMS), laser power (LP), and hatch distance (HD); however, a proportional relationship is presented between laser scanning speed (LSS) and AVMS. The average displacement (AD) presented an inverse relationship with LSS and HD, while a proportional correlation has been presented between LP and AD. Average thermal distribution (ATD) revealed an inverse effect on AVMS and a proportional effect on AD. In the printed parts, only austenite-gamma phase was identified along (111), (200), and (220) orientations, with a lack-of-fusion defect in the morphology.