| EH40 steel as the base and 316 L steel as the composite plate,the surface properties of 316 L steel and the mechanical strength and processing properties of EH40 steel are combined.Hot rolling has become one of the main methods for producing stainless steel clad plates because of its advantages of economy,high efficiency and smooth interface.However,non-uniform deformation and non-uniform structure distribution will occur during hot rolling,which seriously affects the uniformity of sheet properties,while the internal micro-structure of metal materials directly affects its external characteristics.Therefore,it is very important for improving the uniform distribution of structure in the thickness direction of stainless steel clad plate to master the evolution of grain size during rolling and to study the influence of various factors on the uniformity of grain distribution.In order to realize the uniform rolling of 316L/EH40 composite plate along the thickness direction of the rolled piece,the effects of rolling process on the uniformity of forming performance were studied from macro and mesoscopic scales.The thermo-mechanical coupling model of 316L/EH40 composite plate hot rolling was established by DEFORM-3D finite element software.The hot rolling simulation of316L/EH40 composite plate under different rolling processes was carried out.The interface bonding of stainless steel composite plate was determined according to the interface stress and strain conditions.The rolling reduction rate of interface bonding at different initial rolling temperatures was obtained.Based on the rheological stress curve of bimetal,316 L and EH40 composite plate hot rolling were established.Based on the dynamic recrystallization model of EH40 and the macroscopic simulation results,mesoscopic simulation of 316L/EH40 composite plate with interface bonding was carried out.The effects of different initial rolling temperature,rolling reduction rate and rolling speed on grain size at different locations in the thickness direction of base and clad plate were studied.The simulation scheme was designed by orthogonal test method,and the effects of blooming temperature,rolling reduction rate and rolling speed on the uniformity of grainstructure were obtained.The significance of the influence factors was analyzed.The hot rolling simulation analysis was carried out for the optimized parameters combination of orthogonal test,and the grain size distribution and its evolution along the thickness direction of 316L/EH40 composite plate under different rolling processes were obtained.The rolling parameters with good uniformity of grain structure were determined.Based on the optimized parameters of orthogonal test,the multi-pass rolling schedule was formulated,and the numerical simulation of 316L/EH40 composite plate was carried out for multi-pass reversible rolling.The temperature,stress/strain distribution along the thickness direction of the plate was obtained.Based on the results of macro-scale,the grain structure changes of each layer during five-pass hot rolling were analyzed,and the uniformity of grain structure in each pass was obtained.The law of change.Using Gleeble-3800 hot compression test machine,the compression specimens were obtained under the condition of optimum parameters combination.The hot compression test was carried out with the random combination of two sets of parameters in the orthogonal test table,and the compression specimens were compared with the compression specimens under the optimum rolling parameters.The metallographic structure of three groups of specimens was observed,and the grain size distribution at each position under each technological parameter was obtained,and the process was analyzed.The homogeneity of the lower grain structure was compared with the simulation value to verify the accuracy of the numerical simulation.Tensile tests were carried out on the specimens with better rolling parameters to verify the correctness of the optimized process method. |
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