Study To The Forming Process Of Composite Seamless Steel Tube Of Carbon Steel/Stainless Steel Piercing And Multiple Pass Rolling

The carbon steel/stainless steel composite seamless steel tube can take advantage ofcarbon steel seamless pipe excellent mechanical properties and low cost characteristics andexcellent corrosion resistance of stainless steel, and have a broad application space in thepetroleum, petrochemical, marine and some other corrosive territories. To research theforming process of the carbon steel/stainless steel composite seamless steel tube have animportant significance and application value in forming process and dimensional accuracy.The forming process of the carbon steel/stainless steel composite seamless steel tubeskew rolling perforation, carbon steel/stainless steel composite seamless steel tubecross-rolling and multiple pass rolling are simulated using advanced nonlinear finite elementsoftware MSC.Marc with element remeshing, thermo-mechanical coupling, and materials,geometry and boundary conditions nonlinear finite element method. The principal researchwork as follows:(1) The forming process of the carbon steel/stainless steel composite seamless steel tubeskew rolling perforation and cross-rolling were simulated. Based on the numerical simulation,the character of stress, strain, temperature distribution parameters and billet trajectory duringthe two roll cross-rolling were obtained by the finite element analysis, and acquired therolling force distribution. The mechanism of tube cross-rolling process was explainedaccording to the stress distribution.(2) The numerical simulation of the Y-type three-roller two stands cold rolling steel tubeforming process was conducted through the finite element analysis. Based on the numericalsimulation, the character of stress and strain distribution parameters during the Y-typethree-roller two stands cold rolling were obtained by the finite element analysis, and acquiredthe section pass metal flow deformation figure. The distribution of the axial stress, circlestress, radial stress and residual stress were drawn in the cold rolling forming process. Themechanism of the tube cold rolling process and the effect of the forming steel tube both thediameter and wall thickness accuracy were explained according to the stress distribution.Based on the residual stress，and then, the hydraulic cylinder bearing capacity with initialresidual stresses under the hydraulic load was studied, compared with the hydraulic cylinderbearing capacity without initial residual stresses, and obtained the connection between theresidual stress and the loads of the hydraulic cylinder. The numerical simulation results showthat the residual stress of the cold continuous rolling steel tube can reduce the hydrauliccylinder circle and radial deformation, which are favorable for reducing the cylinder wear,increasing life expectancy and improving the hydraulic cylinder sealing performance to work,but the residual stress also increases the hydraulic cylinder external wall local area equivalentstress, and will have some impact to the cylinder strength. (3) The numerical simulation of the Y shape three roll two stands cold-rolling carbonsteel/stainless steel composite seamless steel tube process was conducted through the finiteelement analysis. Based on the numerical simulation, the character of stress and straindistribution parameters during the Y shape three roll two cold-rolling were obtained by thefinite element analysis, and acquired the section pass metal flow deformation figure. Thedistribution of the axial stress, circle stress and radial stress were drawn below the Y shaperolling mill along the circle and steel tube. The mechanism of the steel tube cold-rollingprocess and the effect of the forming steel tube both the diameter and wall thickness accuracywere explained according to the stress distribution.(4) The numerical simulation of the Y shape three roll two hot-rolling seamless steel tubeprocess was conducted through the finite element analysis of the three-dimensionalthermo-mechanical coupled elastic-plastic by applying the MSC.Marc software. Based on thenumerical simulation, the character of stress，strain and temperature distribution during the Yshape three roll two cold-rolling were obtained by the finite element analysis. The finiteelement model of the Y shape three roll two stands hot-rolling stainless steel/carbon steeldouble metal composite seamless steel tube was conducted through the finite element analysis.At last, the future study direction on the forming process of hot-rolling carbon steel/stainlesssteel composite seamless steel tube.