Effects of rolling curve on recrystallization evolution during hot radial-axial ring rolling of super lager alloy steel ring

Abstract

Hot radial-axial ring rolling is one typical ring rolling method, which is suited to manufacture a large-scale ring at high temperature. Rolling curve describes the changing process of the cross-section of the blank ring to the target ring. For a certain target ring, when the blank ring is determined, different rolling curves can influence the rolling shape and microstructure of the final ring. In this study, effects of rolling curve on recrystallization evolution during hot radial-axial ring rolling of a super lager alloy steel ring were studied. Firstly, based on the material recrystallization mathematical model, a finite element modeling method for recrystallization evolution of large ring rolling process was developed by adopting subroutine in ABAQUS. The dynamic recrystallization, static recrystallization and metadynamic recrystallization were considered. A comparison between simulation and experiment result was made to verify the prediction accuracy. Then, the design method of the rolling curve was given. Finally, the recrystallization evolution including dynamic recrystallization, static recrystallization and meta-dynamic recrystallization during hot radial-axial ring rolling was revealed. Besides, simulations of different rolling curves were made and the effects on recrystallization evolution were analyzed. The results show that a S-type rolling curve is preferred to realize smaller grain size and more uniform grain distribution.