油气管道焊缝凹陷韧性损伤研究

Study on ductile damage of oil and gas pipeline weld dent

针对含焊缝凹陷管道的失效问题,以X80管线钢为研究对象,采用临界空穴扩张比韧性失效准则与数值模拟相结合的方法对管道焊缝凹陷损伤程度进行了研究,探讨了焊接残余应力应变、焊缝余高、凹陷深度、压头尺寸、内压和偏移距离对焊缝凹陷损伤的影响。结果表明:焊接残余应力应变和焊缝余高使管道焊缝凹陷损伤值增大;焊缝凹陷损伤值随凹陷深度的增加而增大;随着内压的增加,损伤值增幅最大值点在凹陷侧部;压头与管道接触面积越小,焊缝凹陷损伤值越大;凹陷偏移达到一定距离时,凹陷附近的损伤值超过焊缝附近的损伤值,此时凹陷可以视作普通凹陷。

Aiming at the failure problem of pipelines containing weld dent,taking the X80 pipeline steel as the research object,the damage degree of the pipeline weld dent was studied combining the critical hole expansion ratio ductile failure criterion and numerical simulation,and the influence of welding residual stress and strain,weld residual height,dent depth,indenter size,internal pressure and offset distance on weld dent damage was discussed.The results show that the welding residual stress and strain and weld residual height increase the damage value of the pipeline dent.The damage value of weld dent increases with the increase of dent depth.With the increase of internal pressure,the maximum increment point of damage value is on the side of the dent.The smaller the contact area between the indenter and the pipeline,the greater the damage value of the weld dent.When the dent offset reaches a certain distance,the damage value near the dent exceeds the damage value near the weld,and the dent can be regarded as an ordinary dent.