Three-dimension Simulation Of Dynamic Recrystallization Microstructure Of Q420qE Steel During Hot Deformation

The national twelfth five-year plan presents that:high performance property steel has been one of the six new materials in focus. Recent years, with the huge development of transportation industry and large scale construction of bridge engineering, optimizing the quality of the bridge steel becomes more and more important. Comparing with the development situation of the bridge steel aboard, the domestic bridge steel still needs to be enhanced in the aspects of strength, roughness weldability and weather resistance.During the hot rolling manufacturing process of the bridge steel, the evolution of the microstructure during this process has determined the final microstructure and the property of the steel largely, Therefore, It is essential to research on the rules and mechanism of dynamic recrystallization which could be a guideline when optimizing the hot rolling process. Since the deforming trait of the hot compression process is identified with that of the hot rolling process, the dynamic recrystallization phenomenon of bridge steel during this two processes also has some similarities. So, not only researching on the simulation of the dynamic recrystallization evolution of the hot compression process is easy to perform, but also could provide some important reference value to the dynamic recrystallization evolution rules of hot rolling process.By taking the Q420qE bridge steel as the investigated object and using thermal mechanical coupled rigid visco-plastic FEM, this article established the mathematical model of dynamic recrystallization of hot compression process according to the mathematical model port the software provided and emulated the dynamic recrystallization evolution of this steel and influencing rules of different deforming parameters of phenomenological macroscopic and mesoscopic scale based on the integrated researching ways of hot compression tests finite-mathematical coupled model and Cellular Automaton models. The innovation point of this research is simulating the mesostructure evolution and researching the effect of the deforming parameter to it by using the Cellular Automaton method and accomplishing the simulation result of the evolution process of macroscopic-mesoscopic dynamic recrystallization.The experimental results present:①the results of the phenomenological, the macroscopic and the mesoscopic simulation research all indicate the same rules of the influence to the dynamic recrystallization from the same deforming parameter, that is the higher the strain rate and the lower the deformation temperature are, the harder the dynamic recrystallization occurs.②there is a necessary connection between the equivalent strain distribution the dynamic recrystallization fraction distribution and the average grain size distribution of the specimen.③The relative error of the quantitative result given by the three simulation methods lay in a certain range, which means the established model the simulation process and the result are credible.This research not only provides some relative models and simulation methods of the virtual experiment to reveal the microstructure evolution rules of Q420qE bridge steel during hot rolling process, but also is beneficial to analyze the dynamic recrystallizaion behavior and distribution state. The emulation result of the hot rolling process of this steel will guide the rolling control potential to unleash of the dynamic recrystallization area, thus can realize the optimization of the rolling process so that could improve the structure and property.