Effect of Process Parameters on Melt Pool Characteristics and Solidification Process During Laser Powder Bed Fusion of AlSi10Mg Alloy

The laser powder bed fusion (LPBF) process is characterized by a very rapid solidification phase change due to the very small time and length scales of melt pool involved, as a result of which metastable microstructure is usually formed. As the solidification process is controlled by the melt pool characteristics which are governed by the process parameters, it becomes imperative to understand the effect of process parameters on the solidification process and related parameters such as temperature gradient (G) and cooling rate (GR). Hence, in this study, a computational model has been developed and experimentally validated before being put to use in studying the parametric dependence of the solidification parameters during LPBF processing of AlSi10Mg. The thermal and flow field studies are presented to show the melt pool characteristics in real-time and solidification parameters were calculated from the same. The parametric dependence was checked by varying two key process parameters – laser power and scan speed. The results suggest that the melt pool flow field significantly affects the evolution of the solidification parameters which reach magnitudes of the order of 10⁷ K/m (G) and 10⁶ K/s (GR), respectively. In addition, the parametric analysis concludes that different process parameters affect the solidification process differently. While the temperature gradient is more affected by the laser power variation, the scan speed controls the cooling rate.