Microstructure And Properties Of Selective Laser Melting AlSi10Mg Alloy

As a new technology of Additive Manufacturing,more attention has been payed to Selective Laser Melting(SLM).Comparing with the traditional casting,the strength of aluminum alloy has been significantly improved by the process of Selective Laser Melting.However,molding performance of AlSi10 Mg alloy by SLM remains to be further studied.In this paper,AlSi10 Mg alloy moldings were prepared by selective laser melting technique.The influences of process parameters and heat treatment on the microstructure,surface roughness,relative density and mechanical properties of the molded parts were analyzed by X-Ray Diffraction(XRD),metallographic microscope,scanning electron microscope,microhardness tester and tensile testing machine.The results show that:(1)Most of the particle size distribution of AlSi10 Mg alloy powder is between 5 and45?m.The average particle size of the SLM powder can not be too small,because the powder particle size that below 10 ?m will be easily blown by the protective gas and suspended in the molding cavity,which will cause the scattering of the laser beam.So that the output of laser energy will be interfered and the service life of the air filtration system will be reduced.So,It is possible to reduce the use of a powder having a particle diameter of 10 ?m or less in the ratio of powder particle size.(2)The microstructure of the specimens is scaly in the vertical section of the laser scanning and elongated in parallel with the laser scanning.Phase Si is evenly distributed as shape of ring-island in Al matrix,and Al matrix is divided into the shape of small islands after gathering.(3)When the laser scanning speed ranging from 800 to 1000mm/s and the laser power reached 180 W,the defects of inner hole increased with the acceleration of the scanning speed.And the relative density of the tissue is increased by remelting,which reduced the hole defects.The relative density increased by 4.15% and the tensile strength increased by 23.21%.(4)In the same heat input,the higher power and scanning speed,the higher strength of the parts.The tensile strength is 420 MPa when the laser power is 320 W and the scanning speed 1600mm/s.(5)The microhardness and tensile strength of the parts can be significantly improved with heat treatment.After aging at 170 ? for 2 hours,,the microhardness of the molded article was increased from 15 to 30 HV,and the tensile strength increased about 30 MPa.