12Cr1MoVG焊管环焊缝开裂失效分析  

Failure Analysis of 12Cr1MoVG Welded Pipe Girth Weld

作　　者：陈峥 马亚鑫 CHEN Zheng;MA Yaxin(NCS Chengdu Testing and Certification Co.,Ltd.,Chengdu 610213,China;Chengdu Aeronautic Polytechnic,Chengdu 610100,China)

机构地区：[1]钢研纳克成都检测认证有限公司,成都610213 [2]成都航空职业技术学院,成都610100

出　　处：《焊管》2024年第12期87-91,共5页Welded Pipe and Tube

摘　　要：针对某12Cr1MoVG管道在使用过程中出现的环焊缝开裂问题,对管道环焊缝裂纹表面宏观和微观形貌进行观察、断口及腐蚀产物等进行分析,并对裂纹附近组织进行金相、硬度及残余应力等检测。结果表明:裂纹起源于钢管外壁点蚀区,沿径向向内壁扩展;裂纹源区和断面附近的微观裂纹均可见沿晶开裂特征,局部裂纹分叉,末端尖锐,排除了发生晶间腐蚀的可能;另外,焊缝表面存在补焊痕迹,焊缝组织晶粒异常粗大,焊缝存在错边;同时管件内外壁和断面腐蚀产物基本一致,因此焊缝裂纹性质为应力腐蚀开裂。For the girth weld cracking of a 12Cr1MoVG pipeline in the process of using the macroscopic and microscopic morphology,fracture and corrosion products of the crack surface of the pipeline girth weld were analyzed,and the microstructure,hardness and residual stress near the crack were detected.The results show that the cracks originated from the pitting zone of the outer wall,originated from the outer wall of the weld,and expanded radially to the inner wall.The micro cracks in the crack source area and near the section can be seen the characteristics of intergranular cracking.The local cracks are bifurcated and the ends are sharp,which precludes the possibility of intergranular corrosion.In addition,there are repair marks on the surface of the weld,the microstructure and grain of the weld are abnormally thick,and there are misalignment in the weld.At the same time,the corrosion products of the inner and outer walls and the section of the pipe fittings are basically the same.It is concluded that the weld cracks are stress corrosion cracking.

关 键 词：12Cr1MoVG管道 焊缝裂纹 沿晶开裂 应力腐蚀 

分 类 号：TG115.2[金属学及工艺—物理冶金]