Investigation into the laser polishing of an austenitic stainless steel

Abstract

Gas shielding is critical for improving the quality of laser polishing. The processing effects of laser polishing under the chamber and nozzle gas shielding were compared and analyzed. The influence of the volume flow rate on the surface roughness of the polished workpiece was analyzed, determining the optimal volume flow rate (Q = 5 L/min). At the optimum volume flow rate, the effects of laser power and scanning speed on surface roughness were explored in further research on nozzle gas shielding laser polishing with wider application prospects. A shielding gas jet model for nozzle gas shielding laser polishing was established and verified. The influence mechanism of the shielding gas jet on the polished surface topography was explored using the established shielding gas jet model and laser polishing model, revealing the formation mechanism of surface ripples on the polished surface: the shielding gas jet acts as a perturbation of the molten pool, causing the Marangoni instability of the molten pool when the Marangoni number exceeds the critical Marangoni number.