An investigation on the erosion resistance of rare earths nitrocarburized 40 Cr steel

The effect of rare earths (RE) on erosion resistance of nitrocarburized 40 Cr steel is investigated. Results indicate that a significant improvement occurs in erosion resistance of nitrocarburized 40 Cr steel by introducing RE in nitrocarburizing processes comparing conventional nitrocarburizing processes. Measurement of mechanical properties exhibits that both hardness and toughness of nitrocarburized 40 Cr steel increase in the case using RE nitrocarburizing processes comparing the conventional. Metallurgical microscopy reveals that there is an improvement in the nitrocarburizing layer microstructure attributed to an introduction of RE in nitrocarburizing, which results in an improvement in erosion resistance and mechanical properties. Surface morphology observation of tested samples reveals that predominantly furrow-like peeling from plastic deformation are observed in RE nitrocarburizied 40 Cr steel, while the furrow-like peeling with initial cross crack and large grinding peelings takes place in conventionally nitrocarburized samples.