轧制冷却工艺对低合金超高强钢Q1300组织性能的影响

以开发屈服强度大于1 300MPa低合金超高强结构钢为目的,采用不同的轧制及冷却工艺并进行再加热淬火和回火处理,研究了轧制冷却工艺对低合金超高强钢组织性能的影响规律。结果表明,试验钢经控制轧制后奥氏体晶粒被拉长成扁条状,水冷至600℃后再空冷至室温所得到的粒状贝氏体组织较直接空冷至室温的组织细小,高温连续轧制后空冷至室温得到的组织为粒状贝氏体+板条贝氏体;相比高温热轧工艺,采用控轧控冷工艺能增大轧态组织的原奥氏体晶界面积,能有效细化再加热原始奥氏体晶粒,晶粒尺寸可减小3.5μm;经控轧控冷及调质热处理后,钢板具有较好的强韧性,屈服强度为1 345MPa,抗拉强度为1 590MPa,-40℃冲击功为44J,各项性能指标均达到相关标准要求。

Influence of rolling and cooling process on microstructure and properties of ultra- high strength low alloy steel Q1300

In order to develop ultra- high strength low alloy structure steel plate which yield strength more than 1 300 MPa,different processes were employed to investigate the effects of rolling and cooling process on its microstructure and mechanical properties.The results showed that austenite grain were elongated into strips after controlled rolling and the granular bainite microstructure was fine when water cooling to 600 ℃ before air cooling.The initial microstructure composed of lath bainite and a few martensite could be obtained under continues rolling at high temperature.Compared to hot rolling process,controlled rolling and controlled cooling process was able to significantly increase the prior austenite grain boundary area.So the finer reheating austenite grain size was acquired,and the grain size could be reduced by 3.5 μm maximally.After the TMCP and quenching and tempering heat treatment,the tested plate had good combination of strength and toughness,yield strength of 1 345 MPa,tensile strength of 1 590 MPa,and the Charpy impact energy at -40 ℃ could be reached 44 J.All indexes could meet the relevant standard requirements.