Evolution of Microstructures on Stainless Steel induced by Ultra-Short Laser Ablation

Abstract

Ultra-short pulsed laser ablation of stainless steel is accompanied by the evolution of different microstructures. Depending on the fuence, accumulated energy and number of laser passes cones from impurities, laser induced periodic surface structures and conelike protrusion (CLP) evolve at the surface. These often unwanted morphologies can be inhibited by carefully choosing the strategy and laser parameters. Here, the identifed region shows a small processing window for designed 515nm sub 1 ps ablation leading to low surface roughness. CLP are still not well understood and here a pre-cursor structure is reported. Subsequently, the CLP growth is grain orientation and polarization dependent and studied in more depth. Preferentially, CLP start to evolve at the (101) grain orientations with linear polarized laser radiation. Moreover, a nanoindentation study reveals robust mechanical properties, which could be beneficial for tribology applications in the hydrodynamic regime.