Research On The Deformation Behavior Of Typical Inclusions In Automotive Steel During Hot Rolling

With the rapid development of China’s automotive industry,people have increasingly high requirements for the performance of automotive steel,and inclusions in steel seriously affect the surface quality and product performance of strip steel.Therefore,relevant scholars have conducted extensive research on the control of inclusions in steel,but most of the research has focused on the control of inclusions in molten steel.The rolling process affects the size and distribution of inclusions,as well as the bonding between inclusions and the surrounding matrix,thereby affecting the performance of steel.Therefore,studying the deformation laws of inclusions during the rolling process is of great significance for improving the performance of automotive plates and strips.In view of this,this article adopts a combination of numerical simulation and experimental methods to study the deformation behavior of typical inclusions Al₂O₃ and Mn S in automotive steel during the hot rolling process,and analyzes the binding situation between the inclusions and the surrounding matrix.The research results can provide guidance for controlling the morphology and distribution of inclusions in the rolling process of strip steel,and are of great significance for improving the quality and performance of automotive steel.The main research content and results obtained in this article are as follows:（1）The morphology and composition of inclusions inside the billet were analyzed using scanning electron microscopy and energy dispersive spectroscopy.The hot deformation law of the experimental steel was studied through hot compression experiments,and the physical parameters were measured.The results show that the main inclusions inside the matrix are Al₂O₃ and Mn S;The flow stress of the experimental steel increases with the decrease of temperature and the increase of strain rate.（2）The deformation behavior of inclusions Al₂O₃ and Mn S during hot rolling was simulated using finite element software.The effects of deformation conditions and inclusion properties on the deformation law of inclusions were analyzed,and verified through experiments.The results indicate that both types of inclusions transform from spherical to flat spherical in shape during the rolling process and migrate towards the surface of the substrate.During the rolling process,there is a strain gradient between the inclusion and the matrix.For Al₂O₃ inclusions,the maximum strain mainly occurs in the matrix near the inclusion,while for Mn S inclusions,the maximum strain mainly occurs on the inclusion.（3）The influence of the interaction between different inclusions during the rolling process on their deformation behavior was simulated,and the mechanism of the effect of the distance between the centers of the inclusions and the size of the inclusions on their deformation was analyzed.The results indicate that the strain distribution between inclusions and matrix is related to the distance between the centers of the inclusions.When the distance between the centers of the inclusions exceeds the critical value,the effect of the distance between the centers of the inclusions on the strain distribution between the inclusions and matrix during the rolling process is not significant.The larger the size of the inclusion,the greater the strain between the inclusion and the substrate during the rolling process.（4）The deformation behavior of inclusions with different deformation abilities during the rolling process was simulated,and the formation and evolution of voids at the contact between the inclusions and the substrate were analyzed.The results indicate that when the ratio of the maximum flow stress of the matrix to the maximum flow stress of the inclusion is less than 1,voids are formed between the inclusion and the contact matrix during the rolling process.