Effect of microstructure on wear resistance for multiple ceramic phases

Fe-Cr-B-C hardfacing alloys with four different Cr contents were produced by plasma transferred arc weld-surfacing process(PTA).The microstructure and ceramic phases morphology were investigated by means of optical microscopy(OP),scanning electron microscopy(SEM) and X-ray diffraction(XRD).The results showed that the alloys were hypoeutectic with primary austenite dendrites interspersed by eutectic carbides and borides.The hard phases consisted of BC₄,Cr₂B,M₇C₃,M₂₃C₆,M₂₃(C,B)₆.The borides with plate,rosette shape were observed in the alloys.The volume fraction of ceramic phases increased as the Cr content increased.In addition,the effects of Cr content on wear resistance were evaluated.The wear resistance of cladding layer increased with Cr content.When the volume fraction of Cr reached 15.9%,a multitude of ceramic phases distributed dispersely in the matrix which formed excellent wear resistant structure;and the well-distributed primary austenite enhanced bond strength between borides and matrix,as a result,the wear resistance reached optimum value.