Investigating the Effect of Nanosecond Laser Surface Texturing on Microstructure and Mechanical Properties of AISI 301LN

Abstract

This study explores pulsed Nd:YLF laser surface modification (LSM) effects on AISI 301LN stainless steel. Laser-treated surfaces underwent SEM characterization, revealing patterns and irregularities. Higher heat input surfaces showed significant microstructural changes, while lower heat input surfaces experienced less alteration. Increased laser spot overlap led to larger exposed areas and higher heat input, influencing groove width, depth, and surface roughness. Three-dimensional reconstructions illustrated the correlation between laser parameters and surface characteristics. XRD (X-ray diffraction analysis) and EBSD (Electron backscatter diffraction) analyses revealed a transformation from austenite to martensite, with an increase in the α’-martensite phase, particularly in patterns with high laser power, attributed to rapid cooling during laser modification. Grain size analysis indicated a 42% reduction post-treatment, enhancing the surface fraction of fine grains. Hardness measurements demonstrated an overall increase in laser-treated samples, linked to fine-grained microstructure formation, induced residual stresses, and the α’-martensitic phase.

Keywords

• metastable austenitic stainless steel
• laser modification
• roughness
• phase transformation