Carbide Precipitation Behavior and Wear Resistance of a Novel Roller Steel

Abstract

High speed steel, which contains more alloy elements, cannot be used to manufacture the forged work roll. Therefore, a novel roller steel was designed on the basis of W6Mo5Cr4V2 (M2) steel. In this study, the carbide precipitation behavior and wear resistance of the novel roller steel were investigated. The Fe-C isopleths were calculated by Thermo-Calc to determine the carbide types, which were precipitated at different temperatures. The phase transformation temperatures were measured by differential scanning calorimeter and then the characteristic temperatures were designed. The phase structures quenched from the characteristic temperatures were measured by x-ray diffraction and transmission electron microscopy. The typical microstructures were observed by field emission scanning electron microscopy with Energy Disperse Spectroscopy. The hardness and wear resistance of the novel roller steel were measured. The results show that the precipitation temperatures of austenite, MC, M6C, M23C6, and ferrite are 1360, 1340, 1230, 926, and 843 °C respectively. When the specimen is quenched from 1300 °C, only MC precipitates from the matrix. At 1220 °C, MC and M2C precipitate. At 1150 °C, all of MC, M2C and M6C precipitate. Relationship between mass fraction of different phases and temperature were also simulated by Thermo-Calc. The hardness of the novel roller steel is a little lower than that of M2 steel, however, the wear resistance of the novel roller steel is a little higher than that of M2 steel with the increase of wear time.