Forging State 2.25 Cr1mo0. 25 V Steel Thermal Deformation Structure Evolution Prediction And Numerical Simulation

In recent years,2.25Cr-1Mo-0.25Vsteel becomes the priority material ofhydrogenation reactor. It is required to have good internal quality, dimensionalaccuracy and operational performance in the production and use. Finite elementnumerical simulation method can not only predict and the internal mechanicalproperties in process of forging forming, but also be able to predict themicrostructure evolution process in the forging. Through the control of theproduction process conditions and the thermal forming process parameters, canrealize the control of the microstructure evolution in the process of forming, canget the forgings organization with good mechanical properties.Firstly, the2.25Cr1Mo0.25V steel forging state material which the forgingratio is9.79has been got by the multidirectional forging method, by heattreatment after forging determined that the material grains are relatively uniform.Then the austenite grain growth law has been studied, and the grain growthmodel has been established. The results show that the grain coarseningtemperature of this steel is1100℃, when the temperature reaches1250℃, grainsize reached120μm regardless of insulation3h5h8h, there will not beparticularly significant growth trend.Secondly, three different groups of grain size which as the initial grain sizeof the hot compression test material have been chosen from the grain growth ofthe experimental data. Stress-strain relationship of the material in the process ofhot compression deformation has been studied by gleeble-1500D thermalcompression experiments. The grains of hot compressed sample by grinding,polishing and corrosion have been observed under the optical microscope, theimpact of different deformation conditions on stress strain curve andmicrostructure have been analyzed. The models of the hot deformation equation,the critical strain, dynamic recrystallization volume fraction, the dynamicrecrystallization grain size and dislocation density have been set up. Thedislocation values in different conditions are calculated according to the formulaof dislocation, the influence of deformation parameters on dislocation density has been analysed.The quantitative and qualitative researches have been obtained for dynamicrecrystallization grain size, recrystallization volume fraction and dynamicrecrystallization microstructure variation under different deformation conditionsduring hot compression. These researches are based on material model andmacro and micro modules of DEFORM-3D software. The results are in linewith the actual situation.The predicted results of the2.25Cr1Mo0.25V steel are consistent with thetheoretical basis, which provides certain organizational guarantee for the nextprocess and has a certain significance to improve the performance of the steel.