316L不锈钢表面激光熔覆Stellite-F合金层的电化学腐蚀行为

采用CO₂激光器在316L不锈钢表面熔覆Stellite-F合金,通过电化学方法研究了Stellite-F熔覆合金层在5wt%NaCl溶液中的腐蚀行为。结果表明:与316L不锈钢相比,与基材呈冶金结合的Stellite-F合金层自腐蚀电位较正、自腐蚀电流密度较小,无点腐蚀现象出现,耐海水腐蚀性能较好;研究发现,熔覆合金层物相主要由γ-Co固溶体与Ni₃C、Cr₂₃C₆碳化物构成,在盐溶液中其腐蚀失效机制为选择性腐蚀,即固溶体合金相作为阳极被腐蚀浸出,碳化物相得到阴极保护暴露析出,同时固溶体相中的Co、Ni组分优先被腐蚀浸出,其余组分形成海绵状结构。

Electrochemical corrosion behavior of Stellite-F laser cladding layer on surface of 316L stainless steel

Stellite-F alloy was cladded on surface of 316L stainless steel using CO2 laser device. The corrosion behavior of the Stellite-F cladding layer in 5wt% NaCl solution was investigated by electrochemical method. The results show that compared with 316L stainless steel,the Stellite-F cladding layer,which is metallurgically bonded to the substrate,has relatively positive corrosion potential as well as smaller corrosion current density without point corrosion,and presents a better resistance to saltwater corrosion. It is also found that the phases of the cladding layer are mainly γ-Co solid solution and Ni3C,Cr23C6 carbides,and the corrosion failure mechanism of the cladding layer in saline solution is selective corrosion rather than pitting corrosion. That is the solid solution phase is etched and leached as an anode,the carbide phase is protected as a cathode,and the Co and Ni components in the solid solution phase are preferentially leached,then the remaining components form a sponge-like structure.