Three-Dimensional Dynamic Modeling of Keyhole and Plume During Pulse Laser Welding

A self-consistent model of laser keyhole welding is developed by having a comprehensive consideration of the three-dimensional fluid flow and heat transfer together with the dynamic evolution of keyhole wall. A sharp interface level-set model is adopted to track the keyhole wall, and all the important phenomena occurring on the keyhole wall, including Fresnel absorption of laser radiation, evaporation across kinetic Knudsen layer, recoil pressure and capillary/thermo-capillary force, are incorporated into the formulation. A species equation is also included to calculate the distribution of metallic vapor in the keyhole. A ray-tracing model is built to simulate the multiple-reflection phenomenon and evaluate the Inverse Bremsstrahlung absorption by plasma and Fresnel absorption by the keyhole wall. The complete model is applied to predict the dynamic process of pulsed laser keyhole welding. The keyhole shape and the liquid flow pattern are studied, and the distributions of metallic vapor and its effects on plasma property are investigated.