直接淬火石油储罐用钢N610E的回火组织与力学性能

 N610E级石油储备罐用钢(12MnNiVR)常用加热调质处理工艺生产。利用OM、TEM等试验方法，研究了石油储罐用钢N610E直接淬火后，不同回火温度对组织和力学性能的影响。结果表明：直接淬火钢经655℃回火，钢板具有最佳综合力学性能，其抗拉强度640MPa，屈服强度570MPa，伸长率22%，－20℃冲击功273J，不同回火温度的N610E钢韧脆?湮露染冢?0℃以下。随回火温度的升高，板条贝氏体回复作用逐渐加强，位错通过运动、合并、重组，相邻板条合并，组织粗化；回火后钢的力学性能变化趋势的非单调性，归因于回火过程贝氏体中位错亚结构的回复软化与碳的脱溶及第二相的析出强化机制综合作用。

Microstructure and Mechanical Properties of Direct Quenched and Tempered N610E Steel for Oil Storage Tank

N610E grade steel (12MnNiVR) for oil storage tank is normally produced by reheating quenching and tempering process. Effects of tempering temperature on the microstructure and mechanical properties of the direct-quenched N610E steels were investigated by OM, TEM and other experimental methods. The results indicate that: after direct quenched and tempered at 655℃, the tested steel obtains the optimum comprehensive mechanical properties with tensile strength of 640MPa, yield strength of 570MPa, elongation of 22% and impact energy of 273J at -20℃, brittle transition temperature of N610E steel tempered at different temperature are lower than -60℃. The recovery of lath bainite becomes gradually obvious with increasing tempering temperature through motion, merging and reorganization of dislocations, which cause lath wider. Mechanical properties variation with tempering temperature shows non-monotonic nature, which attributes to the comprehensive mechanism including recovery and softening process of substructure, and the strengthening mechanism due to carbon dissolution and the second phase precipitation in bainite during tempering.