Co对CrNiMo双相不锈钢组织及耐蚀性能的影响

采用TIG粉末堆焊的方式,在304奥氏体不锈钢基板上制备Co含量分别为0%、1%、2%和3%的CrNiMo双相不锈钢堆焊层。经1 100℃固溶处理后,通过金相组织观察、显微硬度测试、动电位极化曲线和交流阻抗谱(EIS)测试研究了Co对CrNiMo双相不锈钢的显微组织、硬度及耐蚀性能的影响。结果表明:随Co含量的增加,CrNiMo双相不锈钢堆焊层中奥氏体相的比例从52%增大至61%后逐渐减小到41%,奥氏体相的形貌由条状或岛状转变为网格状;Co元素固溶于基体中,促进了富Cr、Mo金属间相的析出,提升了堆焊层的硬度,破坏了钝化膜的稳定性,致使堆焊层的耐蚀性能减弱。

Effect of Co content on the microstructures and corrosion resistance of CrNiMo duplex stainless steel

CrNiMo duplex stainless steel surfacing layers with Co content of 0%,1%,2%and 3%are prepared on 304 austenitic stainless steel substrate by TIG powder surfacing.After solution treatment at 1100℃,the effect of Co content on the microstructures,hardness and corrosion resistance of CrNiMo duplex stainless steel is studied by metallographic observation,microhardness test,potentiodynamic polarization curve and electrochemical impedance spectroscopy(EIS).The results show that with the increase of Co content,the proportion of austenite phase increases from 52%to 61%and then decreases to 41%,and the morphology of austenite phase changes from strip-like or island-like to grid-like;the solid solution of Co element in the matrix promotes the precipitation of Cr-rich and Mo-rich intermetallic phases,improves the hardness of the surfacing layer,destroys the stability of the passivation film,and weakens the corrosion resistance of the surfacing layer.