Cr5钢等温贝氏体相变的研究

Study on Isothermal Bainite Transformation of Cr5 Steel

采用热膨胀仪测试了Cr5钢加热、冷却和贝氏体等温过程中的热膨胀曲线,研究了Cr5钢在不同温度和时间保温后的贝氏体/马氏体。结果表明,Cr5钢奥氏体化后在380、350、320℃保温,在350℃保温时贝氏体转变的孕育期最短,在320℃保温时贝氏体片最细。在350℃分别保温10、30、60、360min,随保温时间延长,组织中下贝氏体含量逐渐增加,马氏体量逐渐下降。贝氏体片条对奥氏体晶粒的分割产生细晶强化。贝氏体内部大量弥散析出的细小碳化物以及高硬度的马氏体基体,使贝氏体/马氏体复合组织有望获得较佳的强度和韧性。

The thermal dilatometer was used to test the dilatation curve of Cr5 steel in the whole heat treatment process, and the microstructure of the material after isothermal bainite holding for different keeping time and temperatures was studied. The results show that the bainite isothermal holding at 350℃ exhibits the shortest incubation time and the width of the bainite plates holding at 320 ℃ is narrowest. As the bainite holding at 350℃ for different time（10 min, 30 min,60 min, 360 min）, the lower bainite content increases and martensite reduces with the preservation time getting longer. The grain refinement effects of bainite plate and a great number of tiny dispersed carbides, togethering with hard martensite substrate, which can result in a good performance in strength and roughness for material promisingly.