Microstructure And Performance Of AlSi10Mg Alloy Prepared By Laser Melting Deposition

With the continuous development of the automotive industry and the aviation industry,the requirements for lightweight,large-scale and integrated structural components are becoming higher and higher.Laser melting deposition technology can quickly form large-scale integrated components,which has the advantages of low cost,high material utilization,and short processing cycles.AlSi10Mg alloy has the advantages of high strength,small thermal expansion coefficient,good abrasion and corrosion resistance,etc.,which makes the combination of the two hot topics in recent years.In this paper,the research on LMD forming of AlSi10Mg alloy is carried out.The related research and analysis of the forming process and microstructure are performed.The ANSYS simulation software is used to simulate the temperature field distribution in the molten pool during LMD forming.The reasons were verified,and the mechanical properties of AlSi10Mg alloy laser melt-deposited bulk samples were tested.The main tasks are as follows:The AlSi10Mg alloy single-layer single-pass laser melting deposition test was carried out,and the various process parameters were explored.It was found that as the laser power increased,the width and depth of the deposited layer gradually increased,and the height change was not obvious.The pores in the layer microstructure increase first and then decrease,and the microhardness of the deposited layer increases first and then decreases.As the scanning speed increases,the width and depth of the deposited layer and the height decrease gradually.The pores in the microstructure increase first and then decrease,and the microhardness of the deposited layer first increases and then decreases.As the powder feeding rate increases,the width and penetration depth of the deposited layer gradually decrease,and the height increases continuously.The pores in the microstructure of the sedimentary layer increase first and then decrease,and the microhardness of the deposited layer first increases and then decreases.The process parameters were optimized to: laser power 3000 W,scanning speed 12 mm/s,powder feeding rate 6 g/min;the ANSYS simulation software was used to simulate the temperature field distribution during laser melting deposition,and the laser power and scanning were studied.The influence of velocity on the temperature field distribution makes a qualitative explanation for the transformation of the columnar crystal equiaxed crystal: According to the simulation results,it can be seen that the temperature increases and solidifies in the molten pool as the distance from the bottom of the molten pool increases.The gradient gradually decreases and the cooling rate gradually increases,so that the columnar crystal equiaxed crystal transition occurs in the molten pool.The variation law of sample density under different process parameters was studied,and the best process parameters were obtained: the scanning interval was 0.9 mm,and the height of each rise was 0.6 mm;the optical deposition and scanning electron microscope were used to perform block deposition on the sample Analysis of microstructure: The microstructure of the AlSi10Mg alloy laser melt-deposited block has typical lamellar characteristics,with coarse columnar crystals as the main part in the fusion zone,and it may form between two close fusion zones.Through-growth columnar crystals;mainly equiaxed crystals in the central region of the molten pool;as the distance from the base increases,the grains gradually refine;the deposited bulk samples and spheroidization and aging heat treatment The mechanical properties of the sample were tested: the micro hardness of the deposited sample was 110 HV,the tensile strength was 159 MPa,and the elongation was 8.5%;after heat treatment,the micro hardness of the bulk sample was about 125 HV;the tensile strength was 217 MPa,reaching the level of casting aluminum alloy,and its elongation is 10.6%.