Exploring the Effects of Laser Surface Modification on AISI 301LN Steel: A Micro-Mechanical Study

This article investigates the surface hardening capability of a metastable austenitic TRansformation Induced Plasticity (TRIP) stainless steel, particularly on AISI 301LN, by laser texturing. This technology produces microstructural surface changes in terms of both phase transformation and grain size modification and, as a direct consequence, the laser influences the surface characteristics, mainly hardness and roughness. In this sense, the key parameters (laser power, scanning speed and position of the focal length) were investigated by using a Design of Experiments (DoE) in detail to better understand the correlation between texturing parameters, microstructural and mechanical changes, always at the superficial level. From all the aforementioned information, the results show that the maximum surface hardening is obtained by increasing the laser power and decreasing the scanning speed. Furthermore, by reducing the focal distance, the depth of the microstructural evolution layer is more significant, while the width is less affected. Finally, a suitable model was developed to correlate the processing parameters here investigated with the resulting surface integrity, in terms of mechanical properties, by means of a regression equation.