Effect of overlapped adjacent tracks on surface morphology in plasma beam polishing of austenitic stainless steel

Abstract The adoption of high energy beam in the area of metallic surface polishing is a novel technique to produce glossy surfaces. In particularly, plasma beam finishing is emerging as a workable and economical option to realize high quality irradiated surfaces. In this paper, effect of overlap between the adjacent tracks on surface morphology during plasma beam finishing was researched through using different offset distances, and AISI 304 austenitic stainless steel was selected to be the test material. Based on considering surface roughness, certain statistic features (e.g. material ratio function and power spectral density function) were analyzed to comprehensively reflect the influence of offset distance. To aid a deeper understanding of the molten pool flow and surface evolution during polishing process, a two-dimension transient model, which consists of magnetic field, electric field, laminar flow and heat transfer, was developed by means of the finite element approach. The multi-track polishing tests showed that although the irradiated surface became smoother, significant bulges were found in the overlapped region between adjacent tracks. The simulation model then verified that these bulges varied with different offset distances, reflecting different dynamic processes. Therefore, the selection of offset distance is important for the optimization of plasma beam polishing.