Effects of Abrasive Rock Type on CVF-Dependent Performance Trends of White Cast Irons in the Inner Circumference Abrasion Test

Although the trends of abrasion performance versus carbide volume fraction (CVF) of white cast irons (WCIs) have been studied to some extent, there remain gaps in understanding of the factors controlling performance. This study addresses three knowledge gaps. Firstly, the influence of testing conditions, more closely reproducing ore chute service, has been determined using the inner circumference abrasion test (ICAT), which included different natural rock types. The benefit of WCI compared to steels was much greater in basalt than in granite or greywacke. Secondly, the current work shows monotonic behavior for granite and greywacke but performance reversal in basalt, demonstrating that the reversal is not due to "more severe" or "high stress" conditions. The literature variously shows monotonic, plateauing, or reversing CVF dependence but has not convincingly explained these behaviors. Thirdly, the Cr/C ratio (previously neglected) shows no effect in granite, but lower Cr/C gives poorer performance in basalt. The trends are explained by relative responses of the microconstituents to different minerals. Basalt abrades both steel and the WCI matrix but not M7C3, thus maximizing the benefit of WCI but creating roughened surfaces with protruding carbides. This promotes carbide fracture in hypereutectic alloys and, hence, the reversal. Harder minerals create less differential and hence less protrusion and no plateau.