钴铬钨合金堆焊接头的组织与断裂分析

Analysis on Microstructure and Fracture of Co Cr W Alloy Surfacing Joint

利用电子显微技术对钴铬钨合金堆焊接头进行了组织和断口分析，结果表明堆焊层组织由钴基固溶体和碳化物构成，在常温冲击下呈准解理断裂．低碳钢上直接堆焊和加不锈钢过渡层堆焊接头的熔合区，组织主要是钴基固溶体，在冲击作用下出现韧性断裂，但前者熔合线出现脆硬组织，后者熔合区与堆焊层间有剥离现象，这些均不利于接头的结合．然而前者的熔合线组织是可改善的，因此在低碳钢上直接堆焊钴铬钨合金是可行的．

The microstucture and impact fracture of Co Cr W alloy surfacing joint are investigated by means of SEM.The results show that the microstructure of surfacing metal are coposed of Co based solid solution and carbide,and that structure presents quasi cleavage fracture under room temperature impact test.For the fusion zone of two different joints-surfacing directly on mild steel and surfacing on an additional transition metal layer,the microstructure is mainly Co based solid solution,and the fracture characteries is toughness fracture. Besides,in the former case there is hard and brittle microstructure in fusion line;and in the latter case peeling between surfacing metal and fusion zone is observed,which are harnful to jioning of metals.However,it is found that the structure in fusion line of the former can be improved.As a result,it is practicable for Co Ce W alloy to surface directly on mild steel.