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设计了X80级抗大变形管线钢的合金成分,采用TMCP热轧及轧后两阶段控制冷却技术,完成了试验室制备并实现了工业试制。利用SEM、TEM和拉伸、冲击试验等分析方法研究了不同冷却条件对组织与性能的影响。研究结果表明,采用空冷+水冷两阶段冷却工艺后可得到铁素体+贝氏体双相组织的X80抗大变形管线钢,当加速冷却中终冷温度为450℃、冷却速度为20℃/s时,组织中铁素体与贝氏体相得到最佳配比,M/A相尺寸约为1μm,组织均匀性良好,试样得到最优的强度塑性匹配。
The alloy composition of X80 grade large strain pipeline steel was designed. The TMCP hot rolling and post-rolling two-stage controlled cooling technology were used to complete the laboratory preparation and industrial trial production. The effects of different cooling conditions on microstructure and properties were studied by SEM, TEM, tensile and impact tests. The results show that X80 large strain pipeline steel with ferrite + bainite dual phase structure can be obtained by air-cooled + water-cooled two-stage cooling process. When the final cooling temperature is 450 ℃ and the cooling rate is 20 ℃ / s, the optimal ratio of ferrite to bainite was obtained. The size of M / A phase was about 1μm, and the microstructure was well homogenized. The optimal strength plastic matching was obtained.