Study On Asymmetric Roll Forming Process And Warping Mechanism Of Sandwiched Stainless Steel Clad Plate

316L/EH40 clad plate with Ni sandwich has excellent mechanical properties and high bonding strength.Through asymmetric rolling,the precise control of rolling process parameters is the prerequisite to ensure the flatness of clad plate.The mechanical model of asymmetric rolling and the warping variation of clad plate are key bases for determining the rolling process.The purpose of this paper is to prepare a stainless steel composite plate with excellent flatness.Through the methods of theoretical calculation,numerical simulation and experimental verification,the asymmetric rolling forming process of stainless steel composite plate with interlayer and the law of warping variation are investigated.Based on the theory of engineering method,a force analysis on the stainless steel clad plate was performed by directly adding a thin interlayer.Considering the linear distribution of normal and shear stresses in the section of clad plate unit body between the layers of metal,the mathematical model of asymmetric rolling force of sandwiched clad plates was established by means of force balance equation.The effects of shear yield stress ratio,roll speed ratio,and friction factor ratio on the stress distribution of unit body on each layer were studied.Meanwhile,the position change of neutral point and connection point under different reduction rates were discussed,which provide a theoretical basis for the subsequent development of asymmetric rolling processes for sandwiched stainless steel clad plates.Relying on MSC.Marc finite element analysis software,a multi-pass reversible rolling simulation of 316L/EH40 clad plate with Ni interlayer is performed to analyze the temperature field,stress field,strain field and residual stress changes,which verifies the accuracy of the asymmetric rolling force mathematical model.the minimum reduction of interface bonding of the asymmetric hot-rolled the steel clad plate was clarified,which provides theoretical guidance for subsequent asymmetric hot rolling test of sandwiched stainless steel clad plate.Through the MSC.Marc finite element analysis software,a three-dimensional simulation model of 316L/EH40 clad plate with Ni interlayer was established,and the effects of roll speed ratios,friction factor ratios between rolled piece and upper/lower roll and the first reduction ratio on warping deformation,plastic strain and rolling force were studied;considering the influence of each parameter on the length of rolling deformation zone and the warping curvature of clad plate during asymmetric rolling,the preferred process parameters were derived for subsequent tests.Four final rolling samples with the same thickness and different processes were conducted by the two-roller asynchronous hot-rolling experimental machine.The rolling force changes during the forming process and the rolled clad plate warpage were measured.The accuracy of rolling force mathematical model and the warping change rate of clad plate were verified.Through the microstructure observation and the mechanical property test,the variation of microstructure and mechanical properties during the forming process were analyzed.The influence of process on the microstructure and mechanical properties of clad plate was studied,and the rationality of the preferred process parameters were verified.Through the above work,a set of process parameters can be obtained to prepare a high-quality 316L/EH40 clad plate with excellent flatness,which can provide a reference for asymmetric hot-rolled forming of sandwiched stainless steel clad plate.