Research On Self-Adaptive Control Method And Microstructure Evolution In Rolling Process Of Super-Large Stainless Steel Ring

The research object of this topic is the Φ16 meter stainless steel seamless support ring for the fast reactor,which is made of 316 austenitic stainless steel.Radial and axial rolling is the optimal forming process for this type of seamless ring.The structure of the stainless steel ring is super large and overweight,its outer diameter is nearly 16 meters,and its weight is nearly 130 tons.During the forming process,excessive deformation speed can easily lead to cracking,high temperature will lead to the rapid growth of grains and low temperature will lead to greater deformation resistance.Faced with such limitations of forming parameters,traditional manual control is difficult to ensure the coordination of the movement of each roll.The main microstructure evolution behavior that affects the mechanical properties during the rolling of 316 austenitic stainless steel is recrystallization.At present,there is a mixed crystal phenomenon after the 16-meter ring is formed,which easily leads to unstable mechanical properties.Due to the lack of corresponding research methods in the evolution of recrystallization,it is difficult to effectively solve the problems of microstructure and properties.In this paper,the macroscopic control method and microstructure evolution research technology during radial and axial rolling of super-large stainless steel ring is studied through theoretical analysis,finite element modeling technology development,cellular automata(CA)simulation technology development,experimental verification,which can provide theoretical basis and technical methods for the automation of super-large ring productionIn terms of macro control,a finite element simulation auxiliary software based on ABAQUS is developed with reference to the industrial auxiliary control system,which realizes automatic modeling and online monitoring of the rolling process.And virtual sensors are set in the finite element to realize real-time feedback of various parameters in the rolling process through secondary development.Finally,the real-time measurement and feedback control simulation modeling technology for the radial and axial rolling process of super-large ring is developed.Using the above model,the motion characteristics of each roll during the rolling forming process are studied,and an adaptive control method for super-large ring based on the target state is established from the perspective of the stability and dimensional requirements of the rolling process.This method makes the rolling process more stable,reducing the macro defects of the formed ring,and improving the dimensional accuracy of the ring,which finally makes the ring obtain a better shape.In terms of recrystallization evolution,the cellular automata(CA)method is used to establish the dynamic recrystallization,sub-dynamic recrystallization and static recrystallization evolution models of 316 austenitic stainless steel.Finally,the CA and the finite element method are combined to construct a cross-scale structure evolution prediction model and establish the ABAQUS-CA macro-mesoscopic co-simulation method for the recrystallization evolution of the super-large austenitic stainless steel ring during the radial and axial rolling process,finally the C++ language is used to write the simulation software.It provides a research method for locating the key factors that affect the recrystallization evolution process and the final recrystallization grain size and uniformity,and optimizing the forming process parameters.