不锈钢表面激光合金化Cr-CrB_2层的腐蚀性研究

Study on corrosion property of laser surface alloyed Cr-CrB_2 layers on stainless steel

为了提高SUS 304不锈钢表面的耐磨损、耐腐蚀性能,采用激光表面合金化的方法制备了Cr-CrB2层,并进行了理论分析和实验验证,取得了合金化层的组织和物相以及电化学腐蚀性数据。结果表明,合金化层组织致密、晶粒细小,与基体形成冶金结合,合金化层由奥氏体、马氏体、铁铬固溶体、碳化物和铬硼化合物组成;合金化层的耐蚀性得到提高,腐蚀速率降低,合金化层的极化曲线具有较长的活化-钝化区间;不锈钢基体发生严重的晶界腐蚀和点蚀,晶界腐蚀以孪晶晶界腐蚀为主,合金化层表面发生晶粒间的晶界腐蚀,伴有晶粒和晶界处的点蚀现象,点蚀坑明显小于基体表面的点蚀坑。这一结果对提高SUS 304不锈钢表面的耐磨损、耐腐蚀性是有帮助的。

： In order to improve the wear and corrosion resistance of SUS 304 stainless steel , an alloyed layer of Cr-CrB2 was fabricated on SUS 304 stainless steel using laser surface alloying .The datum about microstructure , phases and the corrosion property of the alloyed layer were obtained .Dense and homogeneous structure and fine grains were observed in the alloyed layer .A metallurgical bonding interface was formed between the alloyed layer and the substrate .The alloyed layer consists of austenite , martensite, Fe-Cr, chromium carbide and chromium boride .The alloyed layer shows higher corrosion resistance and lower corrosion rate than the substrate .The polarization curve of the alloyed layer has a long activaton-passivation segment .Intergranular corrosion and pitting in the grains and the grain boundaries are observed for substrate , and intergranular corrosion occurs mainly in the boundary .The alloyed layer shows intergranular corrosion in combination with pitting in the grains and grain boundaries .The size of the pitting in the substrate is larger than that in the alloyed layer.The results have a great help on the improvement of the wear and corrosion resistance of SUS 304 stainless steel.