Study On The Microstructure And Mechanical Properties Of AlSi10Mg Selective Laser Melting Sample

Additive manufacturing technology is greatly different from the traditional casting and forging process characterized by “subtractive manufacturing”.Additive manufacturing technology has fast cooling rate and huge thermal gradient,resulting in microstructure and excellent mechanical properties.In order to give full play to the design potential and application prospect of additive manufacturing technology,Al Si10 Mg is designed by selective laser melting process,and the process parameters,layered microstructure,mechanical properties and heat treatment of SLM Al Si10 Mg were studied.The microstructure and mechanical properties of SLM Al Si10 Mg was studied.When the laser power is 280 W,the mechanical properties and density of the sample are the best.The relationship between laser power and density,melt pool structure,microstructure and mechanical properties is revealed.When the laser power is low,the laser energy can not fully melt particles due to the material absorbs less energy,resulting in spheroidization effect,therefore there are many defects such as holes、unfused particles.Materials will also overheat due to ultra-high temperature when the laser power is 320 W,resulting in evaporation,mass loss of metal materials,and the certain reduction in density.The effect of melt pool boundary(MPB)orientation on mechanical properties and fracture path of SLM Al Si10 Mg alloy was studied.The melt pool presents a "fish scale" shape in the SLM Al Si10 Mg due to the laser scanning characteristics.The grain growth direction is parallel to the building direction,and has obvious directional structure.In the process of tensile deformation,the residual stress mainly concentrates on the melt pool boundary,the cracks mainly fracture along the coarse melt pool of MPB in the longitudinal sample.However,the cracks mainly pass through the fine melt pool and deflect at the MPB in the transverse sample.The anisotropy of mechanical properties of 308℃/4h and 530℃/4h samples was found to be gradually reduced.In the original sample,the anisotropy of mechanical properties is caused by the difference of the loading area at the molten pool boundary.In the 308℃/4h longitudinal sample,the equiaxed grains are perpendicular to the loading direction,and the heterogeneity of fine equiaxed grains and columnar grains is the largest,leading to stress concentration and premature fracture at the junction.In the transverse sample,the equiaxed grains were parallel to the loading direction,and the degree of heterogeneity was reduced.The overall deformation was uniform.After530℃/4h heat treatment,the microstructure was highly homogeneous,but the sample still had plastic anisotropy,which was related to the local stress concentration caused by the uneven distribution of columnar grains.