TA15合金粉体制备及其SLM成形性能

Preparation and selective laser melting formability of TA15 alloy powder

采用气雾化法制备激光选区熔化成型用TA15粉体,研究了雾化压力与熔炼功率对粉体粒径、收得率、松装密度及流动性的影响,用SLM成形TA15合金样品。结果表明:随雾化压力增大,15~53μm段粉体D50先减后增,15~53μm段收得率先增后减,松装密度减小,流动性逐渐变差;随熔炼功率增大,15~53μm段粉体D50减小,15~53μm段收得率增加,松装密度先增后减,流动性先好后差;随熔炼功率增大,粉体卫星球减少,球形度较好;随雾化压力增大,粉体卫星球增多,球形度较差;TA15合金粉末SLM成型样品在横截面上可观察到独特的棋盘状格子形貌,格子内部存在交错分布的马氏体组织;纵截面上分布着外延生长的β柱状晶;其拉伸断口有大量韧窝存在α/β相界、α/α晶界中,分布较均匀,均为等轴状小韧窝,且拉伸断口均存在未熔的圆球状金属粉末。

The TA15 alloy powders for selective laser melting were prepared by gas atomizing process. The effects of atomization pressure and melting power on the particle size,yield,loose packing density and fluidity of powders were investigated. Besides,the TA15 alloy sample was prepared by SLM. The results show that with the increase of atomization pressure,for the powders with particle size ranging from 15 μm to 53 μm,D50 increases at beginning and then decreases,the yield shows opposite regularity,the loose packing density decreases and the fluidity gradually deteriorates. When the melting powder increases,for the powders with particle size ranging from 15 μm to 53 μm,D50 decreases,the yield increases,the loose packing density increases firstly and then decreases and fluidity becomes better firstly,and then becomes worse. The increase in melting power leads to a decrease in the number of satellite particles and a better sphericity,while the increase of atomization pressure results opposite regularity. The cross section of TA15 sample fabricated by SLM shows a chessboard like microstructure,in which the martensite exhibits an interlaced distribution,and longitudinal section of that shows epitaxial β-columnar grains. Tremendous equiaxed dimples are uniformly distributed at α/β interface and α/α grain boundary on the surface of fracture of tensile sample.Besides,unmelted spherical powders can be found on the surface of fracture of tensile sample.