Microstructure and abrasion resistance of high-chromium open arc hardfacing alloys

Wear-resisting alloys containing Cr 21%~23%, C 3.5%~4.2%, Si 1.4%~1.6%, B 0%~1.8%(mass fraction) were deposited by metal powdered-type flux-cored wire self-shielded open arc welding.The effects of B₄C content in flux-cored wire on the microstructure and abrasion resistance as well as the solidifying characteristics of weld puddles and the effects of Si, B on the deoxidization of weld beads were studied by the methods of optical microscopy(OM), X-ray diffraction(XRD), scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS).It shows that Si₅C₃ can act as a good homogeneous nucleate core of primary M₇C₃ grain.With the addition of B₄C particles, the volume fraction and the size of primary M₇C₃ grains increase remarkably and their morphology changes from dispersion to aggregation.In addition, the results of wet sand rubber wear tests and the analysis of worn morphology indicate that abrasion resistance depends on the size and the morphology of primary M₇C₃ grains and micro-spalling is the dominating wear mechanism.