Research On Hot Deformation Behavior Of Cr5 Steel And Microstructure Simulation Technology For Heavy Backup Roll Hot Forging Process

Backup roll is a core component of rolling equipment. Because of its large volume, heavy weight and high quality requirements, backup roll is difficult to process and is a typical representative of large forgings. It is usually produced by small batch even single piece. Because of its high cost, it is not allowed to fail. Obviously, the traditional method of the trial and error can not meet the needs of development. Therefore, by studying on the characteristics of backup roll material in hot deformation, modeling the relationships and simulating the shape and microstructure evolution to optimize the forging processes, replace parts of actual forging experiment, short the production cycle and reduce the costs is the most powerful tool to realize the goal of “control shape and property”.Based on the Gleeble-1500 D thermo-mechanical simulation tests of alloy steel Cr5, a model of flow stress and dynamic recrystallization was modeled.The obtained flow stress curves from the compression tests has a typical dynamic recrystallization. The flow stress values of Cr5 steel predicted by the model based Hansel-Spittel showed a good agreement with the experimental result. Base on hot processing map, the hot-working character of Cr5 steel during high temperature forming process has been investigated and the range of hot working process parameters corresponding with stable region and unstable zone has been determined. By using the method of work hardening rate, the dynamic recrystallization critical strain model of Cr5 steel was established. The dynamic recrystallization model was developed by means of regression analysis of the experiment date. The dynamic recrystallization process of Cr5 steel during hot compression was simulated by importing the developed model into FORGE-3D.The simulation results showed a good agreement with the experimental result. This showed the established model can simulate the microstructure evolution of Cr5 steel during hot deformation. The FORGE-3D was used to predict the macroscopic deformation and microstructure evolution during the forging process of backup roll.