A Comparative Study On The Performance Of Aluminum Alloy Parts With Selective Laser Melting And Casting

As the demand for stable electricity increases,the stable operation of the grid metal parts becomes increasingly important.In the case of sudden failure of the grid metal parts without spare parts,the repurchase of the entire grid equipment greatly increase the time and economic costs.The use of Selective Laser Melting(SLM)technology to quickly create or repair parts that cause grid failure can reduce the dependence on spare parts and greatly reduce the power outage time.It has important significance for solving grid component failure and improve the efficiency of electric power construction.The possibility to achieve these applications depends on the performance comparison between SLM parts or repair parts and traditional products.This article takes performance of AlSi10 Mg alloy selection laser melting forming parts and traditional casting as the research object,compare the reasons for the differences,provide data accumulation and theoretical basis for rapid prototyping of grid components is used to replace failed conventional cast grid components.The main research and results are as follows:(1)Firstly,we studied the SLM and casting AlSi10 Mg alloy microstructure and hardness distribution The metallographic structure of the SLM is a typical layer-by-layer overlay characteristics,including laser scanning of the weld line,the remelting area between the layers and a small amount of fine pores in the remelting area.Cooling speed in molten pool leads to fine grain and good microstructure.Laser energy of Remelting area is low and there are many times to melt and solidify lead to grain growth.Due to the rapid melting and rapid cooling of the forming process lead to its grain smaller than the casting Microhardness results show that microhardness of the SLM AlSi10 Mg alloy varies in a small cycle with wave type.The laser inside the pool is concentrated makes the grain fine and the microhardness higher.The low energy and the heat accumulation in the remelting area lead to the thick grain the low hardness.The overall hardness is average and slightly higher than the cast.XRD analysis shows that Si forms a supersaturated solid solution in the Al matrix lead to solid solution strengthening in the process of SLM.(2)Secondly,The mechanical properties of SLM forming and casting AlSi10 Mg were studied.The results show that the mechanical properties of SLM AlSi10 Mg alloy are good.Compared with the casting,the tensile strength increased by 42%,yield strength increased by 54%,impact toughness increased by 53%,fatigue limit increased by 16%.The fine grain strengthening and solid solution strengthening in the process of SLM are the main reasons for the excellent mechanical properties.Fracture analysis shows that SLM forming mostly dimple rupture and casting mostly cleavage or quasi-cleavage fracture.(3)Finally,the corrosion resistance and electrical conductivity of SLM forming and casting AlSi10 Mg alloy as grid parts were studied.The results show that SLM forming sample corrosion resistance is better,it is due to the uniform distribution of alloy elements and the formation of uniform oxide film.There is a large uneven eutectic Si in casting AlSi10 Mg alloy,which led to the surface oxide film is not continuous and the corrosion resistance is poor.At the same time,the formation of supersaturated solid solution during SLM forming process lead to lattice distortion,which causes the electrons to easily collide with the crystal defects causing scattering.Eventually resulting in increased resistivity.