Effect of laser powder bed fusion parameters on solidification, microstructure evolution and defects in IN718: Experimental investigations and analytical formulations

This study investigates the effect of selective laser melting (SLM) based powder bed fusion (PBF) process parameters on the solidification dynamics and microstructure of IN718 using a Non-Dimensional Heat Input (NDHI) parameter. NDHI accounts for both material properties and process variables, offering a systematic approach to analyze their interplay. The correlation between NDHI, grain size, cell spacing, and defect formation has been established and experimentally validated using optical and scanning electron microscopy. This study demonstrates the feasibility of using NDHI as a reliable parameter for understanding the intricate microstructural evolution in SLM-PBF processed IN718. The findings provide valuable insights into the optimization of process parameters, minimizing defects, and enhancing the performance of additively manufactured components. The examination of specimens with constant NDHI revealed that scan power has a more significant influence compared to scan speed and hatch distance. Analytical formulation suggested based on the results can be used to predict the possible microstructures for a given set of SLM-PBF process parameters.