Research on track overlapping during Selective Laser Melting of powders

The Selective Laser Melting (SLM) process fabricates components from powders by adding material and its processing principle is based on track overlapping regime, which has been studied in this paper. The inter-layer stagger scanning strategy was employed to avoid nonuniform distribution of energy input. By theoretical deduction and experimental observation, three types of overlapping regime were revealed: intra-layer overlapping regime, inter-layer overlapping regime and mixed overlapping regime with coexistence of the first two types. The overlapping patterns and the corresponding microstructures were then discussed. Experimental result showed that specimens fabricated by inter-layer overlapping regime had high relative density when track space was not larger than 0.2 mm. A cooling insert with relative density of about 93% was also obtained at track space of 0.12 mm.