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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 expansion curves of Cr5 steel in heating, cooling and bainite isothermal process were tested by thermal dilatometer. The bainite / martensite of Cr5 steel after different temperature and time were studied. The results show that the austenitizing temperature of Cr5 steel is 380 ℃, 350 ℃ and 320 ℃, and the incubation period of bainite is the shortest at 350 ℃. The bainite is the thinnest at 320 ℃. At 350 ℃ for 10,30,60,360min respectively, with the holding time prolonging, the content of middle and lower bainite gradually increased and the amount of martensite gradually decreased. Bainite strips produce austenite grain refinement in the division of austenite grains. Bainite a large number of internal precipitation of small carbides and high hardness martensite matrix, bainite / martensite composite tissue is expected to obtain better strength and toughness.