激光熔覆钴基合金组织及其抗腐蚀性能

采用CO2 激光在 2Cr13不锈钢表面熔覆Co基合金 ,对熔覆层的组织结构及腐蚀性能进行了研究。结果表明 ,选择合适的激光辐照工艺参数 ,可获得性能优异的Co基合金熔覆层。熔覆层的组织为极其细密的枝晶组织 ,由于熔覆层富含Co ,Cr等合金元素 ,因而与 2Cr13不锈钢相比 ,同一电位下Co基合金在 2 3℃ 3 5 %NaCl盐溶液中腐蚀电流密度减小一个数量级。PbSO4盐热腐蚀试验结果表明 ,大量的Co ,Cr促进了CoO ,CoO·Cr2 O3致密保护膜的形成 ,因而熔覆层表现出优异的高温腐蚀性能。

Study on Microstructure and Corrosion Resistance of Laser Cladding Co-based Alloy

Surface on 2Cr13 stainless steel was cladded with Co-based alloy using a high power carbon dioxide laser. The microstructure and the constituent phases and corrosion resistance of the clad layer were investigated. The results show that if laser treating parameters were appropriate, the microstructure of clad layer would be very fine and its corrosion resistance is the best. The corrosion resistance was also improved as reflected by a reduction in the current density of least one order of magnitude as compared with the as-received 2Cr13 stainless steel specimen at the same potential. The improvement in corrosion resistance is due to the increase in Co and Cr content in the cladded layer. Under the condition of high temperature PbSO 4 salt corrosion, high Co content promoted the formation of fine CoO, CoO·Cr 2O 3.The fine dendritic structure and the Co-based alloy oxides help to retard the penetration rate of the sulphur ion which induces the intergranular corrosion.