A step-by-step thermo-elastoplastic analysis of laser beam welding

In recent years, laser beam welding has emerged as a significant contact-free fusion method due to its advantages such as high laser advance speed and minimal thermal distortion. Automation further increases its attractiveness in various industries. However, specific conditions related to temperature gradient, chemical composition, welding speed and mechanical boundary conditions can lead to solidification cracks. These cracks originate from microcracks within the weld and occur during solidification. The mushy zone is particularly prone to solidification cracking due to the dendritic morphology and entrapped liquid phases. To address this problem, this study makes a step-by-step approach using finite element simulations on the macro- and microscale. It first locates the mushy zone macroscopically using a heat source model and then analyzes the evolving dendritic microstructure at the microscopic level in a simplified manner, considering thermal and elastoplastic effects. This enables a more thorough understanding of the critical states at micro- and macroscale which may lead to solidification cracking.