Microstructure Evolution and Wear Resistance Control of Water Quenching Si-Mn-Mo Cast Steel

The effect of austenitizing temperatures at 850, 880, 910, 940, 970 and 1000 °C, respectively, and tempering at 250 °C on the microstructure, mechanical properties, strengthening and toughening mechanism, and wear behavior of Si-Mn-Mo cast steel containing 0.45%C-2.0%Si-1.0%Mn-0.3%Mo-0.8%Cr-0.004%B were systematically investigated. The results indicated that the microstructure of water quenching Si-Mn-Mo cast steel was mainly composed of lenticular martensite, martensite/austenite, bainitic ferrite and retained austenite. After tempering, the homogeneity of the microstructure improved. As the austenitizing temperature increased, the hardness of the steel increased first, and then it remained almost constant, the impact toughness decreased significantly, and the wear loss decreased first and then increased. Under low wear load, the steel austenitizing at 910 °C had excellent wear resistance before and after tempering. Under high wear load, after tempering, the steel austenitizing at 850 °C had the optimum wear resistance. The wear mechanisms were mainly abrasive wear, oxidation wear and adhesive wear.