选区激光熔化MnSi2增强316L不锈钢复合材料的表面质量及耐蚀性能

为改善316L不锈钢在海洋环境下的耐腐蚀性能,通过MnSi₂增强316L不锈钢基体,采用选区激光熔化(SLM)制备MnSi₂/316L不锈钢复合材料。利用Image-Pro Plus软件、光学显微镜、扫描电镜(SEM)及电化学工作站研究了激光功率对316L不锈钢金属基复合材料致密度及耐腐蚀性能的影响,通过Tafel极化曲线和阻抗谱表征其耐腐蚀性能的强弱,并通过点蚀形貌揭示了其腐蚀机理。结果表明:添加MnSi₂是提高316L不锈钢耐腐蚀性能的有效途径。随着激光功率的增大,耐腐蚀性能呈现先提高后降低的趋势,当激光功率达到190 W时,2%MnSi₂/316L不锈钢复合材料的致密度为99.80%,其腐蚀电位为－0.053 V (vs SCE)。同时,2%MnSi₂可以显著改善316L不锈钢的成形质量,提高其耐腐蚀性能,其腐蚀形式为氯离子诱导氯化物生成的点蚀,且点蚀产生位置主要集中在孔隙边界处。

Surface quality and corrosion resistance of MnSi2-reinforced 316 L stainless steel composites fabricated by selective laser melting

In order to improve the corrosion resistance of 316L stainless steel in marine environment, MnSi₂-reinforced 316L stainless steel composites were prepared by selective laser melting(SLM). The effect of laser power on density and corrosion resistance of the 316L stainless steel metal matrix composites was investigated by using Image-Pro Plus software, metallographic microscope, scanning electron microscope(SEM) and electrochemical work station. The corrosion resistance was evaluated by Tafel polarization curve and impedance spectrum, and the corrosion mechanism was revealed by pitting topography. The results show that adding MnSi₂ is an effective way to improve the corrosion resistance of 316L stainless steel. When the laser power reaches 190 W, the density of 2%MnSi₂/316L stainless steel composites is 99.80% and the corrosion potential is －0.053 V (vs SCE). At the same time, the 2% MnSi₂ can significantly improve the forming quality and corrosion resistance of the 316L stainless steel. The corrosion form is the corrosive pitting of chloride induced by chloride ions, and the pitting corrosion is mainly concentrated at the pore boundary.