Effects of LPBF printing parameters on the columnar-to-equiaxed grain transition in FeCoCrNiMn alloys

In this research, laser powder bed fusion (LPBF) technology was utilized to fabricate FeCoCrNiMn high-entropy alloys (HEAs). An integrated approach combining simulation and experimental research was employed to investigate the influence of process parameters on the columnar-to-equiaxed transition (CET) within the molten pool during the LPBF process. Initially, a finite element model was developed to simulate the multi-layer LPBF printing process. This study delved into the effects of various printing parameters, namely laser power, scanning speed, and hatch spacing, on the solidification parameters. Experimental characterization was conducted to provide specific solidification model parameters, thereby validating the accuracy and reasonability of the simulation model. The research systematically and quantitatively constructed a solidification map, which correlates LPBF printing parameters with temperature gradient and solidification rate. This map unveiled a potential relationship between the LPBF solidification parameters and the microstructural morphology of the HEAs. Ultimately, mechanical property tests were performed, confirming that adjustments to the parameters could facilitate the CET to a certain extent, leading to an effective enhancement in the microhardness of the HEAs produced using LPBF technology. This study systematically investigated the LPBF printing of HEA, fine-tuned process parameters to control microstructure, and studied the effects on printed parts. This provides a valuable foundation for optimizing LPBF printing HEAs.