The Effect of the Microstructure on the Wear-Resistance in the Welding Deposited Metal

摘要

The microstructure and wear-resistance of the welding deposited metal of Fe-Ti-Nb-V-C and Fe-Cr-W-Mo-C alloy system (with American MG700 as example) are studyed by using SEM , TEM and MM200 wear testing machine. It is revealed that Ti and Nb promote the formation of dispersed MC type carbide granules, while the carbides of Cr and W or Mo tend to precipitate along grain boundary. The formation of MC carbide granules depletes the carbon content in the matrix, and then low carbon martensite matrix can be achieved. The hard and tough matrix and the granular carbides improve the wear-resistance of the deposited metal. But excessive Ti and Nb induce the formation of bigger granules with sharp corner and result too soft matrix, then the wear-resistance decrease. As to the Fe-Cr-W-Mo-C alloy system, network carbides and high carbon martensite matrix make the deposited metal very brittle. During wearing process, the propagating of microcrack in the matrix induces lots of scraps flake off, which decrease the wear-resistance of the deposited metal. The deposited metal of Fe-0.64Ti-1.18Nb-2.18V-1.43Cr-0.97C alloy system in current study achieve the best wear-resistance.