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研究了自行设计的高强钢 30CrMnSi2NiNb在稍高于Ms点温度经不同等温时间处理后的组织和力学性能。结果发现 ,随等温时间的延长 ,强度和硬度先下降后稍有上升 ,塑性和耐延迟断裂性能则先升高后稍有降低。当等温时间为 30～ 6 0min时 ,强度和硬度为最低而塑性和耐延迟断裂性能达到最高 ,此时抗拉强度约为 15 0 0MPa ,KISCC值约为 2 5MPa·m1/ 2 。组织观察和分析表明 ,随等温时间的延长 ,贝氏体转变趋于完全 ,贝氏体含量增加 ,马氏体含量降低 ,残留奥氏体含量先增加而后降低。可见 ,通过选择合适的等温工艺 ,可以使 30CrMnSi2NiNb钢中的残留奥氏体含量增加 ,从而提高其耐延迟断裂性能
The microstructures and mechanical properties of 30CrMnSi2NiNb high-strength steel designed by ourselves were studied after being treated at different isothermal temperatures slightly above the Ms temperature. The results show that with the extension of isothermal time, the strength and hardness decrease first and then increase slightly, while the plasticity and delayed fracture resistance firstly increase and then decrease slightly. When the isothermal time is 30 ~ 60 min, the strength and hardness are the lowest while the ductility and delayed fracture resistance are the highest. At this moment, the tensile strength is about 15 0 MPa and the KISCC is about 25 MPa · m1 / 2. Tissue observation and analysis showed that the bainite transformation tended to be complete with the increase of isothermal time, the content of bainite increased, the content of martensite decreased, the content of retained austenite first increased and then decreased. Visible, by selecting the appropriate isothermal process, you can make the residual austenite content of 30CrMnSi2NiNb steel increased to improve its delayed fracture resistance