地磁激励条件下X80钢拉伸疲劳过程磁记忆信号变化特征  

Variation features of MMM signals of X80 steel in tensile fatigue process under geomagnetic excitation

作　　者：孟祥波 史永晋 MENG Xiangbo;SHI Yongjin(Drilling Engineering Technology Company,Sinopec Shengli Petroleum Engineering Co.Ltd.;Drilling Technology Research Institute,Sinopec Shengli Petroleum Engineering Co.Ltd.)

机构地区：[1]中石化胜利石油工程公司海洋钻井公司,山东省东营市257000 [2]中石化胜利石油工程公司钻井工艺研究院

出　　处：《油气储运》2023年第7期774-784,共11页Oil & Gas Storage and Transportation

摘　　要：疲劳破坏和应力性损伤是海洋立管主要损伤形式。为研究地磁激励下拉伸疲劳过程中典型海洋立管材质X80钢表面磁场信号变化规律,利用MTS810250疲劳拉伸试验机对X80钢材质试样进行了典型工况下的疲劳拉伸试验。试验过程中借助磁记忆传感器监测拉伸试样表面的磁场变化,借助手持显微镜观察疲劳过程中试样疲劳破坏情况,借助扫面电镜分析断口形貌。结果表明:磁记忆对拉伸疲劳损伤敏感,提出了以去背景磁记忆信号极值H_(E)(X)、切向梯度信号极值的连线斜率S_(K)(X)为特征值的X80钢拉伸疲劳损伤磁记忆检测特征参数。在裂纹萌生时,H_(E)(X)和S_(K)(X)会出现过零点的现象;随着循环周次的增加,H_(E)(X)和S_(K)(X)增加的速度也逐渐加快,跟疲劳过程裂纹扩展规律一致,H_(E)(X)和S_(K)(X)能够很好地反映试样的疲劳破坏过程,可用于海洋立管疲劳损伤的监测。研究成果可为磁记忆检测方法在海洋立管疲劳损伤检测的现场应用提供参考。Fatigue failure and stress damage are the main damage forms of marine risers.To study the variation rule of surface magnetic field signals of X80 steel during tensile fatigue process under geomagnetic excitation,the fatigue tensile test of X80 steel specimens under typical working conditions was carried out with an MTS810250 fatigue tensile testing machine.During the experiment,the variation of magnetic field on the surface of the tensile specimen was monitored by a magnetic memory sensor,the fatigue failure of the specimen was observed by a handheld microscope,and the morphology of the fracture was analyzed with the help of scanning electron microscope(SEM).The results show that the magnetic memory is sensitive to the tensile fatigue damage.Thus,the characteristic parameters of magnetic memory detection for tensile fatigue damage of X80 steel were proposed,which took the extreme value of magnetic memory signal with background removed H_(E)(X)and the line slope of the extreme value of tangential gradient signal S_(K)(X)as the eigenvalues.As a result,zero crossing phenomena occur to H_(E)(X)and S_(K)(X)in the stage of crack initiation.The acceleration of H_(E)(X)and S_(K)(X)speeds up with the increase of the fatigue cycle,which is consistent with the crack growth law during the fatigue process.Generally,H_(E)(X)and S_(K)(X)can reflect the fatigue failure process of the specimen,and they can be used to monitor the fatigue damage of marine risers.This research results could provide a reference for the field application of the magnetic memory detection method in the fatigue damage detection of marine risers.

关 键 词：海洋立管 X80钢 拉伸疲劳 金属磁记忆 特征参数 

分 类 号：TE973[石油与天然气工程—石油机械设备]