坡度X70管线钢全自动外焊接头组织与性能  

Microstructures and properties of fully automatic welded joints of X70 pipeline steel with slope

作　　者：韩彬 高建章 周聪 贾彦杰 刘雪光 谢斐 牛盛源 李立英 HAN Bin;GAO Jianzhang;ZHOU Cong;JIA Yanjie;LIU Xueguang;XIE Fei;NIU Shengyuan;LI Liying(School of Materials Science and Engineering in China University of Petroleum(East China),Qingdao 266580,China;Southwest Pipeline Company Limited of PipeChina Group,Chengdu 610095,China;Offshore Oil Engineering Company Limited,Tianjin 300461,China)

机构地区：[1]中国石油大学(华东)材料科学与工程学院,山东青岛266580 [2]国家管网集团西南管道有限责任公司,四川成都610095 [3]海洋石油工程股份有限公司,天津300461

出　　处：《中国石油大学学报（自然科学版）》2024年第3期145-153,共9页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家重点研发计划(2021YFA1000103);国防科技创新特区项目(22-05-CXZX-04-04-29);国家管网集团重点科研计划(CLZB20211);山东省重点研发计划(2020CXGC010207,2022CXGC010202)。

摘　　要：采用全自动外焊工艺对坡度为25°的X70管线钢进行焊接,利用光学显微镜和背散射电子衍射(EBSD)对焊接接头组织进行观察,并对焊接接头进行拉伸、弯曲、硬度、冲击和裂纹尖端张开位移(CTOD)等试验。结果表明:上下坡口的粗晶区宽度和焊接残余应力不同,上坡口粗晶区宽、残余应力大;焊接位置明显影响内表面熔合线冲击功,平焊和立焊位置内表面熔合线冲击功远低于仰焊位置,是接头的韧性薄弱区;焊缝冲击功较高而CTOD值较低,建议评定焊接接头韧性应同时考虑冲击功和CTOD值;根焊区是焊接接头的危险区,易引起环焊缝失效,建议采用等强或高强匹配,焊接工艺评定应区分山区和平原地区,对山区条件下接头进行焊接工艺评定时一定要重点关注根焊区。A fully automatic welding technique was used to weld X70 pipeline steel with a slope of 25°.The microstructures of the welded joint were observed by an optical microscope(OM) and electron backscattered diffraction(EBSD).Meanwhile,the mechanical experiments on the welded joint such as tension,bending,hardness,impact and crack tip opening displacement(CTOD) were performed.The results show that the width of the coarse-grained heat-affected zone(CGHAZ) and the welding residual stress of the upper and lower grooves are different.In the upper groove,the width and the residual stress are both bigger.The welding position obviously affects the impact energy at the fusion line of the inner surface.The impact energy at the fusion line of the inner surface in the flat and vertical welding positions is much lower than that in the overhead welding position,which is the weak toughness zone of the welded joint.The impact energy of the weld is high but the CTOD value is low.Thus it is recommended to consider both the impact energy and CTOD value when evaluating the toughness of the welded joint.The root welding zone is the dangerous area of the welded joint,which is easy to cause the failure of the girth weld.It is recommended to use equal strength or high-strength matching welding materials in the root welding zone.In the welding procedure qualification we should distinguish mountainous areas and plain areas.When performing welding procedure qualification for welded joints under mountainous conditions,the root welding zone must be paid attention to.

关 键 词：大坡度 X70管线钢 全自动焊 显微组织 韧性 

分 类 号：TG442[金属学及工艺—焊接]