Abstract: Microstructure evolution in hot ring rolling is an important factor affecting its mechanical behaviors. The microstructure evolution during hot ring rolling is studied using the simulation and experimental methods. A 3D coupled thermo-mechanical finite element(FE) model of the whole hot ring rolling process is built using the Simufact software. The effects of the initial temperature, height-diameter ratio and upsetting speed of the initial billet on grain size and dynamic recrystallization of hot rolled rings are investigated and the profile of grain and pearlite are observed. The results show that the grain size and pearlite lamellar spacing of the workpiece gradually decrease in the whole process. With increasing the initial temperature, the average volume fraction of dynamic recrystallization and grain size increase, and the uniformity of dynamic recrystallization and grain size improve. With increasing height-diameter ratio and upsetting speed, the average volume fraction of dynamic recrystallization increases while the average grain size decreases, and the uniformity of dynamic recrystallization and grain size improve. The results provide an important theoretical basis and practical significance for establishing the hot ring rolling theory and improving the microstructure properties of hot rolled rings.

Key words: hot ring rolling;numerical simulation;microstructure;mechanical behaviors