Knowledge of residual resilience of welded steel pipes

　　Residual stress of welded steel pipe caused by the residual elastic bending moment in the billet has a significant impact on the service performance of welded steel pipe. Therefore, in order to ensure the safety and reliability of pipeline operation, the customer usually carries out a clear quantitative restriction on the residual elastic bending control of welded steel pipe and attaches it to the requirements of more. Strict technical requirements for replenishment of steel pipe orders. This practice has become a common practice at present. In the manufacturing process of AISI 304 Stainless Steel Welded Steel Pipe, the strip is fed into the up-coil shaper along a certain angle and direction. After the bending deformation of the three-roller bender, the sizing and forming of the outer or inner supporting rollers, and the welding of the inner and outer welding devices, a part of the elastic bending moment will remain in the finished tube blank. This part of the elastic bending moment is balanced with the moment needed to keep the billet round, and the billet itself is in a state of elastic recovery at all times. If the tube blank is cut along its axis and the circumferential restraint is removed, the residual elastic-complex bending moment will be freely released, resulting in the tube blank elastic-complex. This is known as the residual resilience problem of welded steel pipe.