The effects of rolling process and tempering temperature on microstructure and mechanical performance of experimental steel are studied. The results show that the yield ratio and elongation of the experimental steel are lower under noncontrolled rolling; under off-line tempering after controlled rolling, the tensile and yield strength decrease slightly with the increase in quenching temperature, the yield ratio decreases and the elongation increases; under the condition of controlled rolling, ultrafast cooling (UFC), and off-line tempering, the microstructure is fine martensite lath and a large number of fine precipitates, the steel has the highest strength and elongation. With the increase in tempering temperature, the tensile strength of the experimental steel decreases gradually, the elongation increases monotonously, the yield ratio and impact energy increase first, and then decrease. After comparison and analysis, it is found that the best performance can be obtained by direct online UFC after controlled rolling, and then tempering at 630 °C, that is, tensile strength 908 MPa, yield strength 863 MPa, yield ratio 0.95, elongation 21.41%, and impact energy 94 J at −100 °C.

中文翻译：

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轧制和热处理工艺回火对Cr-Ni-Mo高强船用钢组织和力学性能的影响

研究了轧制工艺和回火温度对实验钢组织和力学性能的影响。结果表明，非控制轧制试验钢的屈服比和延伸率较低；控轧后离线回火时，抗拉强度和屈服强度随淬火温度升高略有下降，屈服比降低，延伸率增加；在控轧、超快冷（UFC）和离线回火条件下，组织为细小的马氏体板条和大量的细小析出物，该钢具有最高的强度和延伸率。随着回火温度的升高，实验钢的抗拉强度逐渐降低，延伸率单调增加，屈服比和冲击功先增大后减小。经过对比分析发现，控制轧制后直接在线UFC，然后在630℃回火可以获得最佳性能，即抗拉强度908 MPa，屈服强度863 MPa，屈服比0.95，延伸率21.41 %，-100 °C 时的冲击能量为 94 J。