硼及回火温度对超高强海洋工程用钢板组织及性能的影响

为改进调质态超高强海洋工程用钢的力学性能,研究了2炉不同硼含量的钢。经控制轧制后,在实验室条件下采用不同回火温度处理以确定最佳热处理温度,并对实验钢板进行金相组织观察,利用扫描电镜和透射电镜讨论分析了硼及回火温度对组织、性能的影响。实验结果表明,硼有利于提高钢板的淬透性,含硼钢600℃回火可以满足E690的性能要求;随回火温度的提高,含硼钢和无硼钢的强度降低,伸长率升高,含硼钢的变化幅度比无硼钢大;含硼钢在630~660℃存在明显的回火脆性区,而无硼钢具有较好的回火稳定性;无硼钢在650℃回火可以满足E550的性能要求。

Effects of B and Tempering Temperature on Microstructure and Mechanical Properties of Extra High Strength Offshore Plate

In order to improve the mechanical properties of quenched and tempered offshore plate, two kinds of steels with different B contents were studied. After controlled rolling, the samples were quenched and tempered at different temperatures under laboratory condition. The microstructures were examined by microscope, SEM and TEM to investigate the effects of B and tempering temperature on the microstructure and mechanical properties. The results show that B can improve hardenability of the steel. When tempered at 600??, the mechanical properties of B-bearing steel can meet the requirements of E690. As tempering temperature increased, the strengths of both B-bearing steel and B-free steel decrease while the elongations increase. But the changes in strength and elongation of B-bearing steel are larger than that of B-free steel. There is a temper brittleness zone at 630-660?? for B-bearing steel, while B-free steel has a better tempering stability. When tempered at 650??, the mechanical properties of B-free steel can meet the requirements of E550.