Effect Of Processes On Microstructure And Properties Of AlSi10Mg Alloy Produced By Selective Laser Melting

Selective Laser Melting?SLM?technology is a rapid prototyping technology that has been rapidly developed in recent years.Construct a 3D model from a computer,use a laser beam to melt the metal powder,and directly form high-performance complex metal parts through material accumulation.AlSi10Mg alloy is one of the most widely used cast aluminum alloys,and is widely used in aerospace,automobile engines and other fields.In this paper,AlSi10Mg molded parts were prepared by selective laser melting technology,and the influence of the forming process under relatively high laser power and the subsequent heat treatment process on the microstructure and properties of the material was studied.The results show as following:Increasing the scanning speed or hatch spacing will reduce the density of the sample.To get high-density parts,a small hatch spacing and layer thickness should be selected.The optimized process parameters range is:laser power is 350 W,laser hatch spacing is0.06⁰.08 mm,laser scanning speed is 1200¹400 mm/s and the layer thickness is 30?m.The microstructure of the AlSi10Mg alloy sample prepared by SLM is composed of fine equiaxed?-Al matrix grains and eutectic structure between matrix grains??-Al+Si?.A high-energy laser is used as a heat source to form a supersaturated Si element in the?-Al matrix,and the?-Al matrix has a grain size of less than 1?m.The formed part is formed by melting multiple layers,and the microstructure of the single molten pool and the lap joint can be divided into a fine crystal region?middle of the molten pool?,a coarse crystal region?the junction between the molten pool and the molten pool,and a remelted region?and heat affected zone;the micro-hardness can reach 174 HV_0.2.Under the T6 heat treatment process,the laser scanning trajectory has been unresolved,supersaturated Si precipitates from the?-Al matrix and is uniformly distributed in the?-Al matrix in a spherical shape.After heat treatment,the lattice constant of?-Al becomes larger.The precipitated Si coalesces and grows by the time of solution treatment increases.The microhardness decreases after T6 heat treatment.The ultimate tensile strength and yield strength of SLM-formed AlSi10Mg alloy in the form of forming are 483 MPa and 330 MPa,which is 1.6 times that of conventional castings,and the elongation is equivalent to that of castings.After solution treatment and artificial aging,the tensile strength and yield strength of SLM-formed AlSi10Mg samples prepared by SLM decreased,and the elongation increased to 7.9%,which is about 3 times that of traditional castings;the micro-hardness decreased to 88.3⁹2.6 HV_0.2 after T6 heat treatment.