Numerical Investigation of Keyhole and Melt Pool Stability in Laser Welding of Stainless Steel

Abstract

During the laser welding process, the weld seam geometry and the occurrence of defects such as porosity, humping, or cracks exhibit nonlinear behavior. Laser welding simulations have the advantage that they allow the investigation of these complex processes with a very high temporal resolution, thereby providing deeper insight into them. The aim of this work is to analyze the laser welding of 316L stainless steel up to a plate thickness of 4 mm using a high-fidelity multiphysical simulation model. The investigation focuses on a three-dimensional parameter space defined by power, feed rate, and beam shape. The study shows that, in a physically reasonable parameter space, two different keyhole modes with satisfactory welding results exist, as well as a transition region with welding defects. In addition, an explanation for the stability of the different keyhole modes is provided.