Research On Microstructure And Properties Of High Entropy Alloy Reinforced Stainless Steel Composites By Additive Manufacturing

Selective laser melting is one of the important forming methods for additive manufacturing.Due to the advantages of good quality of processed parts,high material utilization,easy forming of complex parts,and excellent comprehensive performance of molded parts,it is used in aerospace,mold,automobile,biomedical engineering,etc.Widely used in many fields,it has gradually become a research hotspot at home and abroad Compared with traditional processing methods,laser melting in selected areas has its unique advantages.Selective laser melting of metal parts with complex structures and personalized structures has been widely used,but there are still many problems in the quality of shaped parts,especially the formation of metal composite materials,and the selective laser melting process parameters affect its forming quality One of the important factors,so this article uses 316L stainless steel powder and high-entropy alloy element powder as raw materials,through different process parameters(laser power,scanning speed,scanning interval)to produce 316L as a matrix composite material,systematically study the process parameters for SLM The main research results of the microstructure and mechanical properties of the technically formed composite materials are as follows:the composite materials formed under different process parameters of laser melting in selected areas,the main defects are micropores,microcracks and a small amount of unmelted metal.By observing the microstructure of the HEA/316L composite material and comparing the metallographic structure under three different laser energy densities,it is found that the austenite structure of the composite material has an increasing trend with the increase of laser energy density.The microstructure of HEA/316L composite material formed by SLM technology is anisotropic in different forming directions.The internal structure is mainly cell crystal and columnar crystal,and the intercrystalline distance is less than 1?m.The defects in the composite material are mainly pores and small size For cracks,the laser power has a significant effect on it,but the laser power does not have much effect on the microstructure distribution.EDS composition analysis shows that the distribution of main elements in different areas of the composite material is almost the same under the same process parameters,and the distribution of main elements in the composite material is almost the same under different process parameters.The element distribution is relatively uniform,and the process parameters have little effect on the element distributionThrough the analysis of the mechanical properties of the composite material,as the laser power,scanning speed,and scanning distance increase,the porosity of the HEA/316L composite material decreases first and then increases.The hardness of the composite material increases with the laser power and the scanning speed.It showed a trend of increasing first and then decreasing,but the effect of scanning interval on the hardness showed a fluctuating change,and the change range was not large.When the laser power is 170W,the porosity is the lowest 0.69%,the hardness reaches the highest 285.7HV,the tensile strength also reaches the maximum 635.9MPa,23%higher than the as-cast 316L stainless steel,the highest elongation is 37.0%,lower than the as-cast 316L stainless steel 39%elongation.When the scanning speed and scanning distance are 700mm/s and 0.09mm respectively,the porosity is also low,and the composite quality is better,the porosity is 1.69%and 1.53%,the hardness is 275.3HV and 269.5HV,tensile The strength is above 620MPa,respectively 634.6MPa and 628.6MPa.In the tensile fracture of the composite material,small tough dimples can be seen,which are mainly manifested as ductile fracture.Based on the above factors,when the laser energy density is 99J/mm3?111J/mm3,the performance of all aspects of forming composite materials is better.The best process parameters of SLM technology forming HEA/316L composite materials are laser power 170W and scanning speed.700mm/s,scan interval 0.09mm.