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Research On Microstructure Evolution And Prediction Of30Cr2Ni4MoV Steel In Hot Deformation

Posted on:2014-02-06Degree:MasterType:Thesis
Country:ChinaCandidate:L Y PanFull Text:PDF
GTID:2251330392464414Subject:Mechanical engineering
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Research on the multiple microstructure evolution rule of30Cr2Ni4MoV steelapplied to heavy forging and building the prediction model of microstructure distributionare of great significance for controlling the quality of large forgings during the hotforming. Based on the data analysis, which is obtained by the Gleebe-1500thermo-mechanical simulation tests, the evolvement mechanisms of material, includingdynamic recrystallization, metadynamic recrystallization, static recrystallization and graingrowth, have been systematically studied and kinetic equations are established. Then thesekinetic equations are applied to finite element software of Deform-3D, in order to predictthe distribution of microstructure. Compared the result of tests in the same hotdeformation conditions with the value of simulation, the error is small, which validated thereliability of microstructure models.By the hot compression simulation test, the stress-strain curves under differentdeformation conditions are acquired. These models of models of grain growth, DRX,MDRX and SRX are built. All parameters of these models are obtained through thedata-fitting method. And then these models are to prove correct by the metallographicexperiment.Analyzes the importance of thermal physical parameters to numerical simulation oftemperature distribution field, and designs a simple experiment method to acquireequivalent thermal parameter. Combining the heat transfer experiment and the numericalsimulation software, the parameters can be deduced by using the approximation method ofsimulated data and the measured data. Through the method, the equivalent black degreecoefficient is measured which is0.25-0.30in the forging interval from850℃to1260℃.And the coefficient of the die steel loading equivalent heat transferring is also confirmedwhich is1.0kW/(m~2· K).Through the finite element software, simulates the hot deforming process strictlyaccording to the parameters in the actual processing and thermo-physical parameterswhich are measured by trials. Experiment results are closed to simulation results in termsof the percentage and grain size distribution of recrystallization which indicate the validity of those models.
Keywords/Search Tags:30Cr2Ni4MoV steel, hot deforming, prediction of microstructure, finiteelement simulation
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