Effect of welding on residual stress of ERW steel pipe

　　During the construction of natural gas and oil pipeline stations, the installation of valves, meters and flanges should be tapped in the main channel. It is difficult to identify the straight seam position of the base pipe by high-frequency resistance welding. The installation of some lugs is very close to the welding seam. Therefore, it is very necessary to deeply study and analyze the influence of the boss on the basic pipeline. In this paper, the residual stress distribution of high frequency longitudinal resistance welded pipe is analyzed, and the influence of welding position of different boss on residual stress is analyzed. The stress increases sharply and the longitudinal welding residual stress is affected when the boss installed on the ERW pipe is much larger than the parent pipe.

　　ERW pipeline

　　The distribution of residual stress in welded pipe is closely related to the forming process. HFW resistance welding is the cross section of a circular tube after rolling, which makes use of high frequency current and proximity effect to make the induction current highly concentrated on the edge of the open edge to make the temperature of the tube rise rapidly to the welding temperature, and the extrusion roll is extruded. The dimension and hydraulic pressure test after welding are important processes leading to axial residual stress greater than circumferential residual stress. After high frequency welding, on-line heat treatment can improve the microstructure and properties of weld and heat affected zone, thereby reducing residual stress near weld and weld.

　　The residual stress of the steel tube is small, and the residual stress is greater than the circumferential residual stress. The maximum axial and circumferential yield strength is about 38% and 29% of the base metal. The residual stress of ERW pipe and its longitudinal weld is lower than the residual stress of the tube. The yield strength of base metal is about 24.5%-33.6% and 16.4%-21.5%, and there is stress concentration.

　　http://www.xysteelpipe.com/info/Effect-of-welding-on-residual-stress-of-ERW-steel-pipe-1111-1.htm

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