Simulation Of Microstructure Evolution Of Weathering Steel Cu-P-Cr-Ni-Mo During Hot Forming Process

New type Cu-P-Cr-Ni-Mo weathering steel has been widely used for manufacturing the train carriages for its excellent cold formability and weatherability. But with higher requirements for Cu-P-Cr-Ni-Mo weathering steel properties are proposed because of the rapid development of railway transportation and the railways extending to some areas of tough weather conditions, such as tableland. The final properties are obviously affected by the complex changes of the microstructure during hot deformation process. Consequently, it has a important theoretical significance and application value for the forming technology to study the microstructure evolution of Cu-P-Cr-Ni-Mo weathering steel during hot forming.The compression tests on Cu-P-Cr-Ni-Mo weathering steel are carried out by Gleeble thermal simulator. The results indicate that the true stess-strain curves of Cu-P-Cr-Ni-Mo weathering steel show the characteristics of dynamic recrystallization. Peak stress increases with the decrease of temperature or the increase of strain rate; the microstructure evolution is influenced by process parameters, which shows that higher deformation temperature, lower strain rate or larger strain will be conducive to dynamic recrystallization.The mathematical models of dynamic recrystallization of Cu-P-Cr-Ni-Mo weathering steel are set up and the hot compression simulation is carried out by using DEFORM-3D. The simulation results show that there is a kind of inhomogenous deformation, the effective strain, strain rate and temperature of central area of the sample are highest, where the dynamic recrystallization translates completely. The dynamic recrystallization volume fraction and average grain size are obviously influenced by deformation conditions.Dynamic recrystallization models based on cellular automata are established. The microstructure evolution during hot compression process is simulated by the microstructure module of DEFORM-3D and the effect of deformation conditions on dynamic recrystallization is investigated. The results show that dynamic recrystallization translates during hot compression and the simulation results are consistent with the experimental results, which illustrate the rationality of finite element models and the cellular automata models.