Study On Dynamic Recrystallization Behavior Of PcrNi3MoV Steel

The development of the metal processing industry is moving towards its digitalization.The main purpose of this research is to integrate the hot forming behavior modeling,numerical simulation and laboratory research of PCr Ni3Mo V steel for its digitalization.In this paper,the Gleeble-1500D thermal simulator was used to conduct thermal compression tests on PCr Ni3Mo V steel samples at a deformation temperature of 950?1200?,with a strain rate of 0.01?10 s^-1,and on an engineering strain of 60%to obtain the flow stresses under different deformation conditions mentioned above.The results shown that the flow stress curve characteristics is of dynamic recrystallized type when the strain rate is of 0.01 and 0.1 s^-1,and the curve characteristics is of dynamic recovery type when the strain rate is of 1,10 s^-1.A series of experimental values of critical,peak,and steady state strain and stress of PCr Ni3Mo V steel during dynamic recrystallization were obtained by a work hardening rate method.Based on these test value,the Forge critical strain model,Kopp peak strain and steady state strain models were established,and also based on the critical strain and steady state strain,the dynamic recrystallization diagram of this gun steel was drawn;Based on Sellars model,the peak stress,steady state stress and saturated steady state stress models were established.Based on the hot compression test datum,a typical flow stress models of PCr Ni3Mo V steel were established such as Inoue Katsuro model,Zhou Jihua-Guan Kezhi model,Hansel-Spittel model,Laasraoui two-stage model and three-stage model.Because the accuracy of the results obtained by the Hansel-Spittel model is good,and the model is suitable for Forge software,it was used in Forge numerical simulation.The experimental value of dynamic recrystallization volume fraction of PCr Ni3Mo V steel was obtained by the stress-strain curve method,and the Yada,Kopp and Forge models of its dynamic recrystallization volume fraction were established.According to the metallographic photos of the above hot compression test,the experimental average grain sizes were obtained by the intercept method,and the dynamic recrystallization average grain size Forge model was established.The above models were substituted into the Forge finite element to simulate the thermal compression process,and the temperature field,equivalent strain field,equivalent stress field,dynamic recrystallization volume fraction and average grain sizes were obtained.The rules of these fields were analyzed.The final average grain sizes were compared with experimental results,and we found that was basically consistent with the test results.In the last part of the paper,the physical simulation test of low-temperature precision forging+heat treatment was continued to obtain a uniform and fine equiaxed structure with a grain size of about 20.00?m.The error of the grain size before and after heat treatment was within 20%.