Nb含量对X70钢级直缝埋弧焊管组织及强韧性的影响  

Effect by Nb Content on Microstructure and Strength/Toughness of X70 LSAW Pipe

作　　者：何小东 张永青 HAN David 陈越峰 杨耀彬 HE Xiaodong;ZHANG Yongqing;HAN David;CHEN Yuefeng;YANG Yaobin(CNPC Institute of Engineering Materials Co.,Ltd.,National Key Laboratory for Service Behavior and Structural Safety of Oil tubular Goods and Equipment,Xi’an 710077,China;International Welding Research Center,Xi’an 710077,China;CITIC Metal Co.,Ltd.,Beijing 100004,China)

机构地区：[1]中国石油集团工程材料研究院有限公司·石油管材及装备材料服役行为与结构安全国家重点实验室,陕西西安710077 [2]国际焊接研究中心,陕西西安710077 [3]中信金属股份有限公司,北京100004

出　　处：《钢管》2024年第1期29-34,共6页Steel Pipe

基　　金：巴西矿冶公司(Companhia Brasileira de Metalurgia e Mineracao)对本项目的支持

摘　　要：检测了Nb含量为0.046%和0.075%的X70直缝埋弧焊管的强韧性,分析了管体的微观组织。结果表明:随着Nb含量升高,管体的平均晶粒尺寸减小,组织由PF+B_(粒)转变为以B_(粒)为主;管体横向拉伸应力-应变曲线均为典型的“拱顶”型,拉伸性能均满足要求,但含量为0.075%Nb的管体的横向屈服强度和抗拉强度较高;Nb含量相同时,C含量越高,其屈服强度和抗拉强度越高;含量为0.075%Nb的钢管具有更好的低温冲击韧性,但含量为0.046%Nb的钢管的韧-脆转变曲线具有更高的上平台能。Nb含量较高、C含量较低的钢管的热影响区也具有更好的低温韧性。探讨了C、Nb元素的含量及组织类型、析出相和位错密度对X70管线钢强韧性的影响。The strength and toughness of the X70 LSAW pipes with 0.046%Nb and 0.075%Nb respectively are tested,and the microstructure of pipe body is analyzed.The analysis reveals that along with the rise of the Nb content,the average grain size of the pipe body is getting reduced,and the microstructure changes from the PF+B particle structure into the structure mainly composed by B particle;the transversal tensile stress-strain curves are all typical dome shape,and all the tensile properties are up to the applicable requirement,whereas the yield strength and tensile strength of the pipe body with 0.075%Nb content are rather high;in case the Nb contents are the same,the higher the C content is,the higher both the yield strength and the tensile strength will be;the steel pipe with 0.075%Nb content shows better lowtemperature impact toughness,while the ductile-brittle transition curve of the steel pipe with 0.046%Nb content shows higher upper platform energy;the HAZ of the steel pipe with high Nb content and low C content also has much better low temperature toughness.Furthermore the effects by the contents of Elements C and Nb and the microstructure types,and the precipitated phase and the dislocation density on the strength and toughness of the X70 linepipe steel are discussed.

关 键 词：直缝埋弧焊管 管线钢 X70 铌含量 微观组织 强韧性 

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]