W对Co基合金熔覆层组织和耐锌蚀性能的影响

Effect of W on microstructure and zinc corrosion resistance of Co-based alloy cladding layers

为了提高热镀锌生产线关键部件的使用寿命并节约热镀锌成本,采用半导体激光器在316L不锈钢表面制备了具有不同成分的两种钴基合金熔覆层.分别对激光熔覆层的组织形貌、成分、相结构、显微硬度及耐锌蚀性能进行了研究.结果表明,W元素的加入使得熔覆层晶粒发生细化,熔覆层组织主要由γ-Co固溶体、Co_3Mo_2Si相和少量Cr_7C_3相组成,同时还生成了少量弥散分布的Co_6W_6C相.添加W元素后熔覆层的平均硬度可达986 HV,相比未添加W元素的Co基合金熔覆层约增加了114 HV,且约为316L不锈钢的4.5倍.与原Co基合金熔覆层相比,添加了W元素的Co基合金熔覆层中弥散分布的Co_6W_6C相使熔覆层耐锌蚀性能大幅度提高.

In order to improve the service life of key components in the hot dip galvanizing production line and save the cost of hot dip galvanizing,two Co-based alloy cladding layers with different compositions were prepared on the surface of 316 L stainless steel with the semiconductor laser. The microstructural morphology,composition,phase structure,microhardness and zinc corrosion resistance of laser cladding layers were studied,respectively. The results show that the addition of W element makes the grains of cladding layer refine. The microstructure of laser cladding layer is mainly composed of γ-Co solid solution,Co_3Mo_2Si and Cr7C3 phases. Meanwhile,a small amount of Co_6W_6C phase forms. The average hardness of cladding layer reaches 986 HV,which is 114 HV higher than that of Co-based alloy cladding layer without the W element,and is about 4. 5 times as that of 316 L stainless steel. Compared with the orginal Co-based alloy cladding layer,the Co_6W_6C phase sparsely distributes in the Co-based alloy cladding layer with Welement,which significantly improves the zinc corrosion resistance of cladding layer.