CrWMn钢中添加微量Mo对网状碳化物的影响

Effect of adding little Mo on network carbide in Cr WMn steel

依靠相平衡热力学方法，基于crWMn钢容易出现网状碳化物的分析，研究了CrWMn钢中添加微量Mo对避免沉淀析出网状碳化物的作用，并计算了加微量Mo的crwMn钢的热处理工艺及其硬度。结果表明：当CrWMn钢中添加0．3％-0．4％Mo时，在奥氏体相区M，C消失而M23C6增加，并因M23C6与M6C相互转变，降低了碳化物优先在奥氏体晶界上沉淀析出的程度；降温至铁素体区后，M23C6也参与沉淀析出和聚集长大的竞争，减轻了在晶界集中的可能性。并且，使钢中碳化物分布更均匀细化。试验和应用表明，在同样的热加工和冷却条件下，含0．3％-0．4％Mo的CrWMn钢能够避免或减轻碳化物网状，碳化物颗粒尺寸约0．5μm，850℃淬火加200℃回火后硬度为62-64HRC，与合金设计预测相符。

By means of phase equilibrium thermodynamic method and based on the analysis resuh of the easy-emergence law of carbides network in CrWMn steel, the effect of Mo content added in CrWMn steel on avoiding carbides network was researched, and the heat treatment process and hardness of CrWMn steel adding a small quantity of Mo content were calculated. The results show that when CrWMn steel adding 0.3% -0.4% Mo, the M3 C carbide disappears and M23 C6 carbide increases in austenite area of its phase diagram, and the precipitation extent of carbides on the austenite grain boundary is reduced due to the M6 C carbide transforming into Mz3 C6 carbide. As the temperature decreasing to the ferrite area of the phase diagram, the competition of the precipitating and the growing of Mz3 C6 lowers the possibility of carbide network to form on the austenite boundary, and meantime, the distribution of the carbides becomes finer. The experimental results and application experience of CrWMn steel with 0.3% -0.4% Mo show that the carbides size reaches about 0.5 μm, and the carbide network can be avoided or reduced under the conventional use conditions. The hardness after quenching at 850℃ and tempering at 200℃ is 62-64 HRC, which is in agreement with the predicted results of the alloy design.