Modeling of humps formation during deep-penetration laser welding

A 3-D transient modeling based on the numerical resolution of the fluid flow ant the heat transfer equations is developed for deep-penetration laser welding at high-welding speed regime, which results in the humping phenomenon. The physical mechanisms included in our model concern matter melting, vaporization inducing a recoil pressure, and resolidification. The implementation of developed procedures called User Defined Functions (UDFs) working interactively with the CFD Fluent code and a dynamic mesh method allowed us to treat the problem with specific and complex boundary conditions. The recoil pressure, fusion, resolidification, and the temperature dependence of the physical properties were thus taken into account. As a result, regular humps could be observed after resolidification on the weld seam.