激光选区熔化成形Inconel718合金的显微组织以及电化学和摩擦学性能

Microstructure and Electrochemical and Tribological Properties of Inconel718 Alloy Formed by Selective Laser Melting

以气雾化法制备的Inconel718合金粉末为原料,采用激光选区熔化(SLM)技术制备了Inconel718合金,研究了合金的显微组织及性能,并与锻造态合金进行对比。结果表明:SLM成形合金垂直于成形方向的组织呈现明显的带状熔化道,平行于成形方向的组织呈现鱼鳞状熔池的界面结构,晶粒为穿过熔池边界的柱状晶;SLM成形合金平行于成形方向的显微硬度(346 HV)略大于垂直于成形方向(324 HV);与锻造态合金相比,SLM成形合金在质量分数3.5%NaCl溶液中的阻抗曲线半径更大,自腐蚀电位与钝化电位更高,自腐蚀电流密度低2个数量级,耐腐蚀性能更优;当载荷为3~10 N时,成形合金的摩擦因数在0.5~0.8,磨损率在5.4×10^(-5)~14.3×10^(-5) mm^(-3)·N^(-1)·m^(-1),均低于锻造态合金。

The Inconel718 alloy was prepared by laser selective melting(SLM) technique with Inconel718 alloy powder prepared by aerosol method as raw materials.The microstructure and properties of the alloy were studied and compared with those of the forged alloy.The results show that the microstructure of the SLM formed alloy perpendicular to the forming direction presented obvious banded melting channels,and that parallel to the forming direction showed the interface structure of fish-scale molten pool;the grains were columnar crystals passing through the boundary of molten pool.The microhardness of the SLM formed alloy parallel to the forming direction(346 HV) was slightly greater than that perpendicular to the forming direction(324 HV).Compared with those of the forged alloy,the SLM formed alloy exhibited a larger impedance curve radius in 3.5wt%NaCl solution,higher free-corrosion potential and passivation potential,and lower free-corrosion current density by two orders of magnitude,indicating better corrosion resistance.The friction coefficient of the SLM formed alloy was 0.5-0.8,and the wear rate was 5.4×10~(-5)-14.3×10~(-5) mm~(-3)·N~(-1)·m~(-1) under the load of 3-10 N,which were all lower than those of the forged alloy.