Mechanism Study Of Weld With Trailing Impact Rolling For Controlling Crack Of Internal High Pressure Forming Pipe

With the development of Internal High-pressure Forming Technology,the technology has been widely used in industrial fields.Tube billet need to be welded before high pressure forming,welding process can make welding residual stress and deformation.It will affect the internal high pressure forming process.So this article put forward that by weld with trailing impact rolling reduce welding residual stress and control internal high pressure forming pipe crackIn this thesis,304 stainless steel thin tube experiment and numerical analysis was carried out.The study results show that: by weld with trailing impact rolling equipment and selected proper weld parameters,the weld joint residual stress can significantly reduce.It provides a theoretical guidance for weld with trailing impact rolling reduce welding residual stress and control internal high pressure forming pipe crack.Seamless tube,seam tube and weld with trailing impact rolling tube internal high pressure forming numerical analysis was carried out after the welding.Stress and strain in internal high pressure forming process were key analyzed.Research results show that: the seamless tube in the bulging area produced 560 MPa circumferential tensile residual stress and the area wall thickness thinning rate is 4 %.In seam tube internal high pressure forming process,squeezing action of extrusion head can reduce weld joint residual stress,but in the transition region its effect reduce,in the transition zone of seam tube produced 271 MPa axial tensile residual stress.Seam tube crack occurred in the transition zone.Weld with trailing impact rolling tube produced 114 MPa axial tensile residual stress in the transition area.Through the contrast analysis of seamless tube,ordinary seam welded tube and weld with trailing impact rolling tube,it is concluded that the influence rule of welding residual stress to internal high pressure forming: axial welding residual stress is the unfavorable factors of the process of internal high pressure forming process.It make tube after internal high pressure forming axial compressed became axial tensile residual stress.So ordinary seam welded tube rupture is easy.By weld with trailing impact rolling technology can reduce axial tensile residual stress and effectively alleviate rupture in internal high pressure forming process.