Nanosecond pulsed laser surface processing of AISI 301LN steel: effect on surface topography and mechanical properties

Samples of the metastable austenitic stainless steel AISI 301LN were subjected to laser treatment with a nanosecond pulsed laser. Scanning speed and laser power were considered as the main process input variables, while the geometrical dimensions of laser tracks (depth and width) and surface roughness were the process responses. The effects of the input parameters on the responses were statistically investigated using analysis of variance (ANOVA). Microstructural characterization of the laser-treated zone was carried out via optical and focus ion beam microscopy, X-ray diffraction, and electron backscattered diffraction, mainly to discern the induced martensitic transformation. Also, tensile tests were performed in specimens with and without laser modification, in order to assess a possible effect on the mechanical response of the steel. The results show that, by increasing the laser power and decreasing the scanning speed, the geometrical dimensions of the laser tracks augment, the surface becomes rougher, and the higher heat input induces more martensitic transformation, whereas tensile properties are not significantly affected.
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