Massively parallel simulation of the melt pool and the solidification grain structure in laser beam welding

• Applicants: Harald Köstler; Dr.-Ing. Matthias Markl
• Subject Area: Joining and Separation Technology ; Computer-Aided Design of Materials and Simulation of Materials Behaviour from Atomic to Microscopic Scale ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434946896

The modeling and simulation of laser beam welding involves a variety of physical effects that continuously interact with each other. In addition to the correct description of the melt pool itself, the effects within the vapor capillary are increasingly becoming the focus of current research. The goal of this subproject is to model the deep welding phenomena in the vapor capillary and their effects on melt pool dynamics as well as solidification conditions, including the resulting grain structure. Through close collaboration with TP2, a suitable model of the vapor capillary will be developed, leading to predictive forecasts of melt pool dynamics and the resulting solidification conditions. The extreme pressure conditions within the vapor capillary, as well as the resulting melt pool velocities, pose a particular challenge to the numerical stability of the melt pool simulation. The underlying Lattice Boltzmann method, including its boundary conditions at the melt pool surface, will be adapted accordingly. The nickel-based material selected in the second phase exhibits a significantly increased susceptibility to solidification cracking, particularly at grain boundaries, compared to the steel from the first phase. Therefore, a cellular automaton for predicting the solidification grain structure will be integrated. The simulated grain structures and solidification conditions will be used by TP6 to predict the dendritic structure on the micro scale as well as the mechanical properties on the grain scale. After thorough validation with experimental results from TP1 and TP2, a directed parameter study will be conducted in combination with the acceleration platform Kadi4Mat from TP7, considering the findings of the entire research group, to determine suitable process parameters for advantageous solidification conditions with minimal solidification cracking probability.

• DFG Programme: Research Units
• Subproject of: FOR 5134: Solidification Cracks during Laser Beam Welding: High Performance Computing for High Performance Processing