油气输送用大直径厚壁埋弧焊管残余应力及控制研究

针对油气输送用大直径厚壁埋弧焊管的残余应力问题，采用盲孔法测试了螺旋焊管和直缝焊管的残余应力，归纳了焊管制造过程中残余应力的演变规律，探讨了钢管制造过程中不同工序下残余应力的分布及其影响因素和控制方法。研究结果显示，板材矫直和钢管成型后的残余应力保持在150～200 MPa，且螺旋成型略大于直缝成型，成型过程的压下量对残余应力的影响有限；钢管焊接是在成型应力的拘束环境下进行的，直接影响焊缝的横向变形与残余应力，使得残余应力峰值不在焊缝中心，而是靠近焊缝区，螺旋焊管和直缝焊管的该区域残余应力均最高；制管过程中后续的水压试验、喷砂和防锈涂敷等工序，使残余应力得到大幅度降低，且分布更加均匀，螺旋焊管和直缝焊管残余应力峰值均保持在200 MPa左右，直缝管更低一些。研究表明，可以通过适当提高水压试验压力和涂敷温度的方法调节焊管残余应力。

Research on Residual Stress and Control of Large Diameter Thick Wall Submerged Arc Welded Pipe Used for Oil and Gas Transportation

In view of the residual stress of large diameter thick wall submerged arc welded pipe for oil and gas transportation, the blind hole method is used to measure the residual stress of the spiral welded pipe and longitudinal welded pipe. The evolution law of the residual stress during the manufacturing process of welded pipe is summarized, and the distribution, influencing factors and control methods of residual stress in different processes of the pipe manufacturing are discussed. The results show that the residual stresses of the straightening plate and the forming steel pipe are maintained at 150～200 MPa, and the residual stress of spiral weld forming is slightly larger than that of longitudinal weld forming. The influence of the press quantity on the residual stresses is limited during the forming process. Pipe welding is carried out under the restrained environment of forming stress, which directly affects the transverse deformation and residual stress of the weld, so that the peak value of residual stress is not in the center of the weld, but near the weld zone, where the residual stress of the spiral welded pipe and the longitudinal welded pipe is the highest. The peak value of residual stress of the spiral welded pipe and the longitudinal welded pipe are kept at about 200 MPa, and the residual stress of the longitudinal welded pipe is lower than that of spiral welded pipe. The research shows that the residual stress of welded pipe can be adjusted by properly increasing the pressure of hydraulic test and coating temperature.