Research On Rheological Behavior And Dynamic Recrystallization Of Medium Carbon Steel Under High Temperature And Heavy Reduction Rolling

The research and development of high temperature and heavy reduction rolling process theory of iron and steel materials and its related technologies have important practical significance for improving the quality of continuous casting billet and enhancing the performance of the final product.In order to obtain high performance slab by high temperature and heavy reduction rolling process,it is very important to control the high temperature characteristics and process parameters of rolling process.Through the deep study of the rheological behavior and dynamic recrystallization behavior of the experimental steel during high temperature thermal deformation process,the process parameters with practical value can be obtained to guide the industrial practice of continuous casting heavy reduction process.At the same time,in the study of the deformation behavior of steel materials,the research on the rheological properties of steel materials near the solidus temperature range is rarely involved.In this paper,the high-temperature thermal deformation behavior of medium carbon steel in the near-continuous casting solidification zone was studied by thermal simulation experiment.The influence of deformation temperature and strain rate on the flow stress and microstructure of medium carbon steel was studied.And the corresponding constitutive relationship of stress and strain and dynamic recrystallization model are established,which not only enriches the material database,but also has important significance for the development of high temperature and heavy reduction rolling process.In this paper,the specific research work is as follows:(1)The high-temperature flow stress curve of medium-carbon steel was obtained by thermal compression experiment on MMS-300 thermal simulator,and the stress-strain relationship of experimental steel under high temperature hot compression deformation was studied.The high temperature plastic deformation material constant and the experimental high-temperature constitutive model of the material in the experimental condition is established.The calculated value agrees well with the experimental data.(2)Research and analysis of dynamic recrystallization process of experimental steel.Based on the experimental results,the dynamic recrystallization model of experimental steels during high temperature deformation was established,including dynamic recrystallization kinetics model and dynamic recrystallization grain size model.Observe the metallographic microstructure of experimental steel,and get the influence rule of deformation process parameter on micro structure.Analyze the influence of deformation parameters on the critical strain of dynamic recrystallization,dynamic recrystallization fraction and dynamic recrystallization grain size.(3)By using the constitutive model and DEFORM3D finite element simulation software,the material model and the initial boundary conditions of the rolling process under high temperature and heavy reduction rolling process are established.The coupled field of temperature and stress-strain during high temperature and heavy reduction rolling is obtained.According to the results of numerical simulation,the deformation process in the thickness direction of the slab is simulated by high temperature compression thermal simulation experiment,and the dynamic recrystallization and deformation characteristics of each part are analyzed.At the same time,carry out the pilot test of experimental steel under high temperature and heavy reduction,the microstructure of slab after deformation is analyzed.