100Cr6轴承钢贝氏体相变行为

Bainite transformation behavior of an 100Cr6 bearing steel

从热力学角度计算了实验钢贝氏体相变温度,分析了不同温度贝氏体相变规律,揭示了相变过程残留奥氏体的稳定性,提出了一种两步短时贝氏体处理方法。实验结果表明：贝氏体相变的鼻尖温度在300～350℃之间,综合考虑相变时间和硬度,选取250℃进行等温处理为最佳工艺;在250℃保温20 min时,存在残留奥氏体含量的最大值,保温时间大于20 min后其稳定性提高,在后续的冷却过程中不发生马氏体相变;在250℃等温处理50 min后升温到270℃保温5 min,相变时间为传统工艺的27%左右,显著缩短贝氏体相变时间的同时并未明显降低硬度和磨损性能。

The bainite transformation temperature of the steel was calculated based on thermodynamic theory. The behavior of bainite transformation of the steel at different temperature was analyzed. The stability of retained austenite during bainite transformation was investigated. The results indicate that the nose temperature of bainite transformation of the steel is in the range of 300 to 350 ℃ , and isothermal temperature of 250 ℃ is recommented for bainitic transformation by takeing into account the transformation time and hardness. The fraction of retained austenite achieves the maximum value when holding at 250 ℃ for 20 min,and the stability of the retained austenite is enhanced with the increasing holding time. The transformation time of two-step （250 ℃ × 50 min-270 ℃ × 5 rain） process, which accelerates the full transformation of austenite without decrease hardness and abrasion performance of the steel,is about 27% of that of traditional bainitic transformation process.