轧后冷却工艺对大输量X80M管线钢显微组织的影响  

Effect of post-rolling cooling process on microstructure of large-transmission X80M pipeline steel

作　　者：刘干 孔祥磊 黄明浩 王杨 张英慧 LIU Gan;KONG Xianglei;HUANG Minghao;WANG Yang;ZHANG Yinghui(State Key Laboratory of Metal Materials and Application for Marine Equipment,Anshan 114009,Liaoning,China;Iron&Steel Research Institute,Ansteel Group,Anshan 114009,Liaoning,China)

机构地区：[1]海洋装备用金属材料及其应用国家重点实验室,辽宁鞍山114009 [2]鞍钢集团钢铁研究院,辽宁鞍山114009

出　　处：《中国冶金》2023年第11期81-87,共7页China Metallurgy

摘　　要：为保证大输量X80M管线钢高强度的同时进一步提高其低温韧性,实现强韧性良好匹配,采用Gleeble-3800型热模拟试验机对其进行模拟轧制研究。利用热膨胀法结合金相法建立X80M管线钢的动态CCT(Continuous Cooling Transformation)曲线,并通过OM、SEM、硬度检测等分析方法,研究了冷速、终冷温度等冷却工艺参数对其组织和硬度的影响。研究发现,随冷速增大,其组织发生多边形铁素体(PF)+珠光体(P)→粒状贝氏体(GB)→针状铁素体(AF)→贝氏体铁素体(BF)的转变,维氏显微硬度也逐渐增加;当冷速为15~25℃/s时可获得以细小均匀AF为主和弥散分布M/A(马氏体-奥氏体)岛组成的理想显微组织;终冷温度对其相组成有明显的影响,随着终冷温度的降低,M/A岛尺寸变小,数量增多,组织逐渐细化。将试验研究与生产实践相结合,最终设定工业化TMCP参数为终轧温度780℃+终冷温度360℃+冷速20℃/s,得到的X80M管线钢板卷具有高强度和优异低温韧性,满足其工程技术要求,并成功应用于西气东输四线重大管道工程。本研究为高强高韧管线用钢的研发提供了技术参考,有力支撑了国家重大管道工程的建设。In order to ensure the high strength of large-transmission X80M pipeline steel and further improve its low temperature toughness,and achieve a good match of strength and toughness,Gleeble-3800 thermal simulation tester was used to simulate rolling.The dynamic CCT curve was established by thermal expansion method combined with microstructure analysis,and the effects of cooling rate and final cooling temperature on the microstructure and hardness were studied by OM,SEM,hardness testing and other analytical methods.The results show that with the increase of cooling rate,the microstructure produces the transition of PF+P→GB→AF→BF,and the Vickers microhardness gradually increases.The ideal microstructure consisting of fine uniform AF and diffusely distributed M/A islands can be obtained when the cooling rate is in the range of 15-25℃/s.Final cooling temperature has an obvious effect on its phase composition.As the final cooling temperature decreases,the M/A island size becomes smaller,the number increases and its microstructure gradually refines.Combining experimental research with production practice,the final industrialized TMCP parameters are set to final rolling temperature of 780℃+final cooling temperature of 360℃+cooling speed of 20℃/s.The obtained X80M pipeline steel coil has high strength and excellent low temperature toughness,which meets its engineering and technical requirements,and is successfully applied in the major pipeline project of West-East Gas Transmission Line IV.This study provides technical reference for the research and development of high-strength and high-toughness pipeline steel and strongly supports the construction of national major pipeline projects.

关 键 词：大输量X80M管线钢 CCT曲线 冷却速度 轧后冷却工艺 针状铁素体 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TE973[金属学及工艺—金属材料]