Development of a Heat Source Model for Narrow-gap Hot-wire Laser Welding

Abstract

Three-dimensional finite element analysis with a special subroutine was carried out to obtain the temperature distribution during hot-wire laser welding with a narrow-gap joint. A moving heat source was modeled with the element rebirth technique, and laser reflection was modeled by heat flux distributed around the front of the weld pool. The model was used to reproduce the phenomenon of hot-wire laser welding with a narrow gap investigated by in-situ observation. The thermal strain for different weld shapes was then calculated to evaluate the susceptibility to solidification cracking. The simulation results were validated with experimental measurements in terms of the thermal cycle history of the molten pool, peak temperature distribution close to the fusion zone, and cross section of the weld bead. The thermal simulation was found to agree reasonably well with the experimental results and it was revealed that hot-wire laser welding is an interesting alternative process that reduces solidification cracking in a narrow-gap joint.