CA single track simulation of laser conduction welding with stainless steel 316L (1.4404)

The study presents a coupled cellular automata (CA) approach for a single track microstructure simulation for laser conduction welding. A high-power CO2 laser beam (1000 W) traverses the substrate, with the beam shaped by conventional optics, which produces a Gaussian profile. The process parameters produce a shallow melt phase maintaining a conduction limited weld seam. The stainless steel material 1.4404 was used as substrate material with a grain size of approximately 20 µm without any filler material. The cooling rates and initial grain size influence the grain morphology and were determined. The size of a single crystal was simulated for different cooling rates. The simulation outputs of the melt pool boundary are qualitatively and quantitatively compared to experimental results. The micrograph results have shown that fine sub cells are developed. This fine cellular microstructure was only satisfactorily resolved experimentally along the melt pool boundary. The simulation results are in acceptable agreement with the experiments at the melt pool boundary. They match in terms of cooling rate, grain angle, and primary dendrite spacing. However, the simulated grains are longer which indicates the necessity of homogenous nucleation in the liquid melt pool.