Modeling and Validation of Heat Source Effects on Keyhole Formation in Single-Pass Laser Processing of Ti-6Al-4V Alloy

This study addresses the lack of accurate predictive models for laser surface treatment of Ti-6Al-4V, particularly under keyhole-mode conditions. An air-cooled ytterbium fiber laser was used at powers of 80, 90 and 100 W with fixed scanning speed to investigate effects on microstructure and hardness. Experimental results revealed martensitic (α’) phase formation, a Ti-oxide layer, with hardness increases of 33%, 40% and 45%, respectively. Finite element simulations using DEFORM-3D™, coupled with a custom subroutine, accurately predicted molten pool geometry and hardness profiles. Among several heat source models, a Gaussian polynomial profile provided the best match with experimental data. A novel modelling approach is proposed, calibrating the heat source via process temperature rather than predefined flux shapes. This strategy enhances simulation flexibility and accuracy. The integrated approach improves understanding of laser–material interactions and supports process optimization for aerospace and biomedical applications.