摘要
管道上体积缺陷与凹陷共同存在是管道损伤中严重的破坏形式。为此开展X80管线钢管的外腐蚀复合凹陷预制,进行凹陷区应变采集和残余应力测试,讨论外腐蚀凹陷状态下的应力应变分布,并分析凹陷区微观组织变化。试验结果表明,外腐蚀凹陷状态下,管道凹陷中心的外壁承受压应力,内壁承受拉应力;凹陷区外壁轴向的压应力随着与凹陷中心距离的增加而增大,出现峰值后压应力逐渐减小,转变为拉应力;凹陷区钢管内壁的径向与轴向均承受拉应力。含外腐蚀凹陷的钢管,承受应力最大的区域位于外壁凹陷区的腐蚀坑边缘,且含腐蚀凹陷的钢管在凹陷变形中承受的应力峰值远高于单纯凹陷。腐蚀凹陷区的应变增量与凹陷深度呈线性相关,凹陷深度≥5%时,应变增幅急剧上升。凹陷区底部和侧壁的晶粒沿着变形最大的方向被拉长,使得凹陷区不同部位表现出不同的残余应力分布状态。
The existence of volume defect and dent on pipelines is a serious damage form. Thus, the prefabricating of X80 pipeline steel pipeline with external corrosion and composite dent is carried out, tests of strain acquisition and residual stress in dent area are conducted,stress and strain distribution under the condition of external corrosion and dent is discussed,and the microstructure change of the dent area is analyzed. The test results show that under the condition of external corrosion and dent,the outer wall of the dent center bears compressive stress and the inner wall bears tensile stress. The axial com - pressive stress of the outer wall increases with the distance from the dent center and decreases gradually after the peak value, then it transforms into tensile stress. The inner wall of steel pipe in the dent area bears tensile stress both in radial and axial directions. For steel pipelines with external corrosion and dent, the maximum stress- bearing area is located at the edge of external corrosion pit, and the peak stress in dent area is much higher than that of steel pipes with plain dent. The strain increment in the dent area is linearly related to the dent depth. The strain increment increases rapidly when the dent depth is more than 5%. The grains at the bottom and side walls of the dent are elongated along the direction of maximum deformation, and the lattice is distorted, which makes the different parts of the dent show different residual stress distribution.
作者
田野
罗金恒
徐春燕
邹斌
朱丽霞
赵新伟
TIAN Ye;LUO Jinheng;XU Chunyan;ZOU Bin;ZHU Lixia;ZHAO Xinwei(West Branch of Petrochina Pipeline Co.,Ltd.;CNPC Tubular Goods Research Institute;National Key Laboratory of Service Behavior and Structural Safety for Petroleum Tubular and Equipment Materials)
出处
《油气田地面工程》
2019年第5期11-15,共5页
Oil-Gas Field Surface Engineering
关键词
X80管线钢
腐蚀凹陷
应变
残余应力
组织形态
X80 pipeline steel
corrosion dent
strain
residual stress
form of organization
