The Study Of Static And Metadynamic Recrystallization Behavior For LZ50 Steel

The axle is one of the key components of the train.Its performance will directly affect the safety of train travel and the development of railway transportation,so the production of axles must be quality and quantity.Although the forging process of the axle is simple,static or metadynamic recrystallization occurs during processing.Recrystallization can produce fine and even austenite grains.Thereby,fine and uniform microstructure is obtained,and the strength,rigidity,plastic and toughness of the axle are improved.In this paper,the double-pass hot compression test of LZ50 steel was carried out using Gleeble-3500 thermal simulator.According to the obtained stress-strain curve,the static recrystallization softening rate was calculated by stress compensation method.The static recrystallization kinetics equation was established.The influence of deformation parameters on static recrystallization volume fraction and static recrystallization rate was studied.The composition and operation rules of the cellular automaton(CA)model were introduced.The static recrystallization mechanism was combined with the cellular automaton model.The thermal compression process of LZ50 steel was simulated according to the grain deformation technology to be closer to reality.The recrystallization nucleation model,grain growth and coarsening model were established by the relationship between dislocation and distortion energy.The simulation step size was corresponding to the static recrystallization time,and the static recrystallization modeling process was described in detail.The static recrystallization behavior of LZ50 steel was simulated by CA method.The initial microstructure of LZ50 steel was obtained and the complete static recrystallization process was analyzed.The simulation results were consistent with the experimental results.The compressed sample was subjected to a polishing corrosion test and grain size was measured.The effects of deformation parameters on recrystallized grain size and average grain size were analyzed by combining experimental data with simulation results.The effects of different deformation conditions on recrystallization nucleation rate and grain growth rate were obtained.The grain orientation and ratio of grain boundary at different angles were analyzed by electron backscatter diffraction(EBSD).The grain misorientation between the various points in the original grain was obtained,and the static recrystallization nucleation mechanism of LZ50 steel was determined.In this paper,the metadynamic recrystallization behavior of LZ50 steel was studied by double-pass hot compression experiments and stress-strain curve was obtained.The true strain was 0.3 to 0.7,and the other deformation conditions were similar to static recrystallization.The metadynamic recrystallization volume fraction was calculated by the stress compensation method.The influence of deformation conditions on the metadynamic recrystallization volume fraction was analyzed,and the metadynamic recrystallization kinetics equation was established.The grain size after metadynamic recrystallization was measured by experiments,and the influence of deformation conditions on the metadynamic recrystallized grain size was analyzed.The range of technology parameters which can obtain fine microstructure was determined to provide theoretical guidance for production.