Modeling microstructural alterations and the formation of keyhole-mode melting on TI6AL4V during single-pass laser ablation

Abstract The present study focuses on developing and validating a finite element (FE) model for simulating the thermo-mechanical phenomena during laser surface treatment of Ti6Al4V alloy, particularly the key-hole mode and its impact on surface quality. This research aims to predict the geometry of the laser track, keyhole shape, and associated hardness variations induced by phase transformations. A 3D rotary Gaussian volumetric heat source model, coupled with a custom user subroutine, has been integrated into the FE code to accurately simulate the laser-induced thermal distribution. This approach ensures precise predictions of ablation, phase evolution, and associated hardness changes. Experimental validation, supported by micrographs, hardness measurements, temperature data, and phase analysis, confirms the model’s capability to capture critical phenomena. Notably, the model successfully represents the formation of the Ti-oxide layer resulting from the martensitic phase transformation, which significantly enhances hardness compared to the base material. This research provides valuable insights into numerical modeling with the aim to optimize laser surface treatments, improving the mechanical properties and functional behavior of Ti6Al4V components, and contributes to advancing the broader field of laser-based manufacturing. Additionally, a different methodology for modeling the heat source based on process temperature, rather than traditional geometric heat flux definitions, was proposed.