F22高强钢的热变形行为与晶粒组织预测

Hot deformation behavior and grain structure prediction of F22 high-strength steel

利用Gleeble-3800热模拟试验机研究了F22高强钢在变形温度850~1250℃、应变速率0.01~5 s^(-1)、最大变形量60%下的流变行为,采用Arrhenius模型建立了基于流变曲线的本构方程。此外,基于F22高强钢的显微组织,建立了动态再结晶体积分数模型与晶粒尺寸模型,并通过工字形锻件进行有限元模拟验证了模型的准确性。结果表明,流变曲线对应变速率和变形温度敏感,流变应力随应变速率的增大而增大,随变形温度的增大而减小。动态再结晶体积分数随变形温度的升高、应变速率的降低和应变的增大而增大;与应变的影响相比,动态再结晶晶粒尺寸受变形温度和应变速率的影响更大,随着变形温度的升高和应变速率的降低,再结晶晶粒尺寸增大。通过对再结晶模型的二次开发,模拟并计算了工字形锻件的晶粒组织特点,模拟结果与实际结果一致,证明了再结晶模型的正确性。

The flow behavior of F22 high-strength steel at deformation temperature of 850-1250℃,strain rate of 0.01-5 s^(-1) and the maxi-mum deformation of 60%was studied by Gleeble-3800 thermal simulator,and the constitutive equation based on flow curves was estab-lished by Arrhenius model.In addition,based on the microstructure of F22 high-strength steel,the dynamic recrystallization volume frac-tion model and grain size model were established,and the accuracy of the models was verified by finite element simulation of H-shaped forgings.The results show that the flow curves are sensitive to the strain rate and deformation temperature.The flow stress increases with the increase of strain rate and decreases with the increase of deformation temperature.The dynamic recrystallization volume fraction increa-ses with the increase of deformation temperature,the decrease of strain rate and the increase of strain.Compared with the effect of strain,the effect of deformation temperature and strain rate on grain size of dynamic recrystallization is greater,the recrystallized grain size increa-ses with the increase of deformation temperature and the decrease of strain rate.Through the secondary development for recrystallization model,the grain structure characteristics of H-shaped forgings were simulated and calculated.The simulation results are consistent with the actual results,which verifies the correctness of recrystallization model.