The effect of nickel, silicon and austenite deep-freezing treatment on the microstructure and wear properties of high chromium white iron containing niobium

摘要

The influence of sub-zero treatments on erosion and abrasion resistance of a high chromium whitecast iron with different amounts of nickel and silicon was investigated. It was found that nickelstabilises the residual austenite in white irons, decreasing their wear resistance. On the other hand, thecorrosion resistance of these alloys is improved by nickel addition. Silicon was found to be anaustenite-destabilising element increasing theγ→M transformation temperature. Up to 58% ofpredominantly austenitic matrix in the alloys containing 3.8% Ni is transformed to martensite by theaddition of 3.6% Si and the application of sub-zero treatments. A tempered martensite matrixstructure was found to offer the best resistance to both erosion and abrasion. SEM observationsrevealed that a martensitic matrix, because of its high hardness, can effectively support the massivecarbides by preventing their fracture during abrasion and erosion processes.