Alloy Design and Application for Avoiding Carbide Network of CrWMn Steel by Phase Equilibrium Thermodynamic Method

Abstract

By the equilibrium phases of the steels with temperature, the causation of being carbide network of CrWMn steel frequently in the manufacture was analyzed, and an alloy design for avoiding carbide network of CrWMn steel was researched. The analyse and research show that in austenite area the boundary precipitation of M3C and M6C carbides during cooling process after forging or hot rolling is preferential origin of carbide network, and in later ferrite area the precipitation and congregation of the carbides should lead on network aggravation. When CrWMn steel adding 0.3~0.4Mo as supplement, in austenite area M3C carbide disappears and M23C6 carbide increases, and it is conceivable of lightenning congregation to austenite boundary as the transformation of M23C6 and M6C reciprocally, and the distribution of diversified carbides should become fine too. The practice results show that the carbide network of CrWMnMo0.35 steel is avoided under normal forging or hot rolling conditions, and the hardness after quenching at 850°C and tempering at 200°C is HRC62~63, which is agreement with alloy design forecast. The experiment and application show that the performance of CrWMnMo0.35 steel is better than that of customary CrWMn steel for machinery knives.