Mesoscale numerical simulation and experimental study on the selective laser melting process of 17-4PH stainless steel

The forming quality of parts produced by selective laser melting (SLM) are closely related to the melt pool behavior and the melt channel formation. In this study, a mesoscale numerical model incorporating critical factors like surface tension, evaporation recoil pressure and Marangoni convection was established for SLM of 17-4PH stainless steel. The standard deviation coefficient of the melt channel width and the lap rate of the melt channel was calculated, which helped identify a suitable process window. Subsequently, orthogonal tests were designed to explore the effects of various process parameters on forming quality. Results indicate that the temperature field of the melt pool remains stably through SLM. As laser power is below 100W, disconnection occurs in the melt channel. Once the laser power exceeds 250W, the spheroidization of the melt channel becomes pronounced. The melt channel exhibits continuity and uniform when the standard deviation coefficient of the channel width is below 10.15%. Additionally, when the melt channel lap rate ranges between 15% and 45%, the lapping areas appear flat. Orthogonal experiments have confirmed the validity of the numerical model. Finally, a combination of process parameters ( P = 200W, V = 800 mm/s, S = 70 μm) yield the specimens with a relative density of 99.376%.