Study on energy input and its influences on single-track,multi-track, and multi-layer in SLM

Abstract

Energy input is crucial in the manufacturing of high-density metal part with smooth surface. In this article, the authors had studied the single-track, multi-track, and multi-layer and had obtained four types of typical tracks, including regular and thick shape, regular and thin shape, regular but occasionally broken shape, irregular and pre-balling shape. The analysis of single- and multi-track experiments showed that the regular and thin shape was the most suitable for selective laser melting (SLM) fabrication. Multi-track experiments proved that dense and smooth surface can be obtained when the overlapping rate was around 30% based on the regular- and thin-shaped track. As a result of the heat accumulation effect during multi-track and multi-layer fabrication, it was possible to obtain ideal track type with less energy input. In multi-layer experiment, the gradually thicken layer was the reason for the surface quality deterioration. The inter-layer stagger scanning strategy, which can improve the quality of the end-use part, was used in this experiment. By testing the 316 L stainless steel samples fabricated by the SLM process, the microstructure can be identified as composed of fine equiaxed and columnar grains, and the samples had higher tensile strength and hardness than castings of the same material, but with lower elongation. The experiments had proved that SLM process can directly produce high dense 316 L stainless steel part with smooth surface.