Replacement of conventionally complex processing for low alloy steel 20Cr2Ni4A by rare earth carburising at lower temperature

摘要

This paper deals with the effects of rare earth (RE) addition on the microstructure and properties of 20Cr2Ni4A steel carburised at 860 deg C. Compared with conventional 920 deg C carburising and other complex treatments, finer and more dispersed carbide precipitates formed in the surface layers. A superfine martensitic structure and a less residual austenite were obtained by direct quenching after RE 860 deg C carburising. The microstructure exhibited a higher microhardness, a wear resistant surface layer, and it also led to an increase in impact toughness. In addition, the heat treatment period for this steel was remarkably reduced by the replacement of conventional complex treatments by RE 860 deg C carburising.