Tribological Behavior of Duplex Stainless Steel with Laser Peening Treatments Without Coating

In this research, the effects of laser shock peening without coating (LSPwC) on surface microstructural changes of duplex stainless steel (DSS) SAF 2205 and its related tribological behavior are studied. Dry sliding tests using ball-on-disc configuration with an aluminum oxide ball as a counterface were carried out on as received (AR) and on LSPwC treated materials with two laser power densities. The analysis of surface features induced by LSPwC and its correlation with friction and wear behavior is attempted. In order to achieve this goal, microstructural studies were carried out by x-ray diffraction (XRD), optical (OM), scanning electron (SEM) and transmission electron microscopy (TEM). Moreover, knoop hardness, roughness and surface residual stress measurements were performed. Regardless of the surface condition, AR or LSPwC, the worn surfaces of materials are characterized by a combination of ploughing and delamination. LSPwC treated specimens exhibits an initially lower friction coefficient but also lower wear resistance in comparison with AR sample. These results are mainly explained by the thermal effects and the higher strain localization at phase boundaries caused by the LSPwC treatments.