Achieving Superior Strength and Ductility of AlSi10Mg Alloy Fabricated by Selective Laser Melting with Large Laser Power and High Scanning Speed

AlSi10Mg alloy was prepared by selected laser melting(SLM)in a high laser power range 300–400 W.The effects of energy density on the relative density,microstructure and mechanical properties of the SLMed AlSi10Mg alloy were studied.The results showed that the SLMed AlSi10Mg alloy fabricated at a laser power of 400 W and a scanning speed of 1800 mm/s had a relative density of 99.4%,a hardness of 147.8 HV,a tensile strength of 471.3 MPa,a yield strength of 307.1 MPa,and an elongation of 9.6%,exhibiting excellent comprehensive mechanical properties.The unique combination of the melt pool structure and microstructure caused by the large laser power and fast scanning was responsible for the excellent performance.The wide and shallow melt pool structure with few defects and proper overlapping between the continuous melt pools were obtained.The growth of columnar crystals was inhibited by a large proportion of equiaxed grains formed at the border of melt pools,and numerous sub-structures were observed within theα-Al grains.This study provided a more efficient process parameters for the preparation of the SLMed AlSi10Mg alloy.The enhanced mechanical property will help to broaden the application of the AlSi10Mg alloy in industry.