碳当量对油气输送管道环焊缝热影响区韧性的影响规律  

Effect of Carbon Equivalent on Toughness of Girth Weld HAZ in Oil and Gas Transportation Pipelines

作　　者：牛辉 张君[1,2] 王磊 毕宗岳[1,2] 崔绍华 韦奉 张鹤松[4] 燕铸 NIU Hui;ZHANG Jun;WANG Lei;BI Zongyue;CUI Shaohua;WEI Feng;ZHANG Hesong;YAN Zhu(Chinese National Engineering Research Center for Petroleum and Natural Gas Tubular Goods Co.,Ltd.,Xi'an 710018,China;CNPC Baoji Petroleum Steel Pipe Co.,Ltd.,Baoji 721008,Shaanxi,China;China Oil&Gas Piping Network Corporation,Beijing 100013,China;Central Iron and Steel Research Institute,Institute for Engineering Steel,Beijing 100081,China;China Petroleum Technology&Development Corporation(CPTDC),Beijing 100028,China)

机构地区：[1]中油国家石油天然气管材工程技术研究中心有限公司,西安710018 [2]中国石油宝鸡石油钢管有限责任公司,陕西宝鸡721008 [3]国家石油天然气管网集团有限公司,北京100013 [4]钢铁研究总院有限公司工程用钢研究院,北京100081 [5]中国石油技术开发有限公司,北京100028

出　　处：《焊管》2023年第12期14-19,共6页Welded Pipe and Tube

基　　金：中国石油天然气集团有限公司“超临界二氧化碳长距离管道关键技术研究”(项目编号2021ZZ01-02);中国石油天然气集团有限公司前瞻性基础性及战略性技术攻关课题“中长距离管道纯氢/掺氢输送关键技术研究”(项目编号2021DJ(JT))。

摘　　要：针对高钢级油气长输管道环焊接头热影响区韧性波动的问题,通过热模拟试验机、金相显微镜、扫描电子显微镜、维氏硬度计以及夏比冲击试验机对试验钢的组织及力学性能进行测试,对比分析了不同碳当量的高钢级管线钢一次粗晶区经不同峰值温度二次热循环后组织和低温韧性的变化规律。结果表明,经二次热循环后,在环焊接头热影响区会出现脆化区,且即使母材韧性处于较高水平,在经历多次热循环后,其低温韧性也有可能减小,通过冶金成分的优化设计可以减小低韧性组织所占比例,从而提高焊缝热影响区的低温韧性;不同试验钢在不同温度下的组织形貌差异表明,粗大的粒状贝氏体组织和大量大颗粒的M/A组元是导致韧性下降的根本原因。通过研究X80钢级管线钢在不同热影响作用后组织及低温韧性的影响,为适用于全自动环焊的高韧性X80管线钢的开发及应用提供理论支持。In order to solve the problem of toughness fluctuations in the heat affected zone of high grade pipeline girth welded joints,the microstructure and mechanical properties of the experimental steel were tested using thermal simulation testing machines,metallographic microscopes,scanning electron microscopes,Vickers hardness testers,and Charpy impact testing machines.The changes in microstructure and low temperature toughness of high grade pipeline steel with different carbon equivalents after secondary thermal cycling at different peak temperatures were compared and analyzed.The results show that after secondary thermal cycling,embrittlement zone will appear in the heat affected zone of the girth welded joint,and even if the toughness of the base material is at a high level,its low temperature toughness may also decrease after multiple thermal cycles.By optimizing the design of metallurgical composition,the proportion of low toughness structures can be reduced,thereby improving the low temperature toughness of the weld heat affected zone.The differences in microstructure and morphology of different experimental steels at different temperatures indicate that the coarse granular bainite structure and many large particle M/A components are the fundamental reasons for the decrease in toughness.By studying the impression of microstructure and low temperature toughness of X80 grade pipeline steel under different heat effects,theoretical support is provided for the development and application of high toughness X80 pipeline steel suitable for fully automatic girth welding.

关 键 词：环焊缝 热影响区 碳当量 低温韧性 M/A组元 

分 类 号：TG407[金属学及工艺—焊接]