A 3D computational model of nanosecond pulsed laser texturing of metals for designing engineered surfaces

Abstract

Laser surface texturing uses a pulsed laser that is scanned on the surface, wherein each pulse produces a crater through material ablation. A variety of textures can be generated depending on the laser parameters and the overlap of the laser spots. This work presents a computational model that can predict the topography of a textured surface produced using a nanosecond pulsed laser. The model involves a multi-physics approach that considers laser ablation with plasma effects and the melt pool fluid dynamics to obtain the crater profile for a single pulse. The 3D surface profile obtained from the single pulse model is mathematically superimposed to mimic the spatial overlapping of multiple pulses. The model predicts surface topography when a laser is scanned along a linear track with successive overlapping tracks. The experiments have confirmed that the proposed model has an accuracy greater than 90 % in predicting surface roughness (Sa), as well as volume parameters such as core void volume (Vvc) and valley void volume (Vvv). It was observed that the variation of these surface characteristics is highly non-linear with the process parameters. Furthermore, the model is used to design engineered surfaces to modify friction coefficient, adhesion, and leakage probability. It is demonstrated that the surface parameters for functional requirements can be modified significantly just by varying the overlap of the laser spots in different directions. The proposed model can be used to create textured surfaces for various applications through an appropriate choice of laser parameters and scanning parameters.