M₇C₃-type carbide and abrasion resistance of Fe-C-Cr-V high chromium hardfacing alloys

High chromium hardfacing alloys containing 0.9-3.0%C,15-20%Cr,2.0-3.0%V(wt.%) were deposited by flux-cored wire submerged arc welding(SAW).The microstructure and carbide morphology were investigated by optical microscopy(OP),scanning electron microscopy(SEM) and X-ray diffraction(XRD).The microstructure consists of martensite,ferrite and austenite,carbide such as primary M₇C₃,(Fe,Cr)₃C and TiC etc.Orientational M₇C₃-type carbide grains distributing in the plane vertical to the hardfacing surface were obtained by the optimization of flux-cored wire and welding speed.The analysis of energy dispersive spectrometer(EDS) indicated that M₇C₃ type carbide was(Fe,Cr,V)₇C₃.In addition,the effects of carbon content on hardness and wear properties were evaluated.Experimental results demonstrated that the abrasion resistance of Fe-C-Cr-V hardfacing alloys was excellent.Dispersed primary carbides of M₇C₃ with the size of 15-25 micron can effectively impede the micro-cutting movement of abrasive particles and deliberately improve abrasion resistance of the hardfacing alloys.