Selective laser remelting of an additive layer manufacturing process on AlSi10Mg

AlSi10Mg samples were fabricated by selective laser melting (SLM) using meander strategy and remelting strategy to gain insight into the variation of the microstructures and microhardness as well as the surface morphology, characteristics of molten pool, relative density and phase identification. The results show that the remelting strategy in SLM improves the surface quality (9.94 mu m) and relative density (99.3%) of AlSi10Mg, at the same time, the shallower melt pool also is attained by remelting step due to the higher thermal conductivity and the reflectivity of laser in solid than powder. The shallower melt pool for second scan remelts the columnar grain near the top of the original melt pool and the solidifies in the same way with as original melt pool, resulting in finer equiaxed grains. The finer microstructures with supersaturated alpha-Al improve the hardness performance of SLMed samples from 117.7 HV0.3 to 121.6 HV0.3.