Research on the Microstructure and Abrasion Resistance of Hardfacing Alloys of Cr8Nb3CSiMnTi System

Abstract

 For solving the problem of insufficient wear resistance of medium chromium alloy，medium chromium wear-resisting alloys belonging to Cr8Nb3CSiMnTi system were fabricated by submerged arc welding using composite powder particles (CPPs) and H08A solid wire as filler materials.The effects of carbon content on the microstructure and abrasion resistance of the as-prepared hardfacing alloys were investigated by X-ray diffractometer (XRD)，scanning electron microscopy (SEM) and attached energy dispersive spectrometer (EDS).Results showed that the matrix of such medium chromium hardfacing alloys consisted of α-Fe and contained such hard phases as (Fe，Cr)7C3，(Fe，Cr)3C and(Nb，Ti)C.With the increase of carbon content，chromium content in the solid solution of α-Fe matrix decreased continuously and the quantity of intra-granular (Fe，Cr)7C3phase increased，whose morphology changed from an isolated shape into a dendritic one，and then a directional aggregation one.Meanwhile，the gap between intra-granular (Fe，Cr)7C3and (Nb，Ti)C became narrower.From the results of wet sand rubber wheel wear testing，it could be obtained that with the increase of carbon content，the alloys’abrasion resistance increased first and then decreased，which was mainly attributed for the increase of the quantity of intra-granular (Fe，Cr)7C3 and the change of the gap between intragranular (Fe，Cr)7C3and (Nb，Ti)C.Moreover，the toughness of hardfacing alloys decreased firstly and then increased，which was not only determined by the quantity of the matrix，but also related to the morphologies and the distribution of intra-granular carbides.Their wear mechanisms included micro-cutting and micro-spalling，and the former was the dominant.

Keywords

• composite powder particles|solid wire|hardfacing|abrasion resistance|microstructure|abrasion mechanism