Investigation into Laser Surface Modification of Stainless Steel

Abstract

Laser surface modification of metals is performed by irradiating a laser beam at the workpiece surface, where the heating and partial melting of metal take place and in turn alter the physical and/or metallurgical structures of metal surface to be a desired feature. However, the use of improper laser heating conditions can decrease the process performance as well as the quality of workpiece surface obtained. To understand the roles of laser in the metal surface modification, this study therefore investigated the effects of laser heating parameters on the roughness and morphology of metal surface. Stainless steel grade 316L was selected as a work sample in this study. Accordingly, average laser power, laser scanning speed and scan overlap were the major process parameters tested in this work, where the surface roughness of laserscanned area was quantitatively and qualitatively analyzed. The experimental results revealed that using high laser power together with slow scanning speed and no scan overlap provided the average surface roughness of up to 0.701 μm. In addition, the formation of metal recast was evidenced in the laserirradiated surface. The significance of this study could bring a deeper understanding of process behaviors and also recommend a practical guideline for controlling the quality of metal surface induced by laser.