摘要
采用Gleeble-3500热模拟试验机,在变形温度为900～1100 ℃、应变速率为0.01～0.1 s-1条件下对Fe-13Mn-4.4Al-0.64C-0.1Ti低密度钢进行热压缩试验,在传统本构模型基础上建立应变补偿本构方程,并进行验证与分析,研究了低密度钢的热变形行为.采用电子背散射衍射技术研究了不同变形条件对试验钢热变形行为和显微组织演变规律的影响.结果表明,试验钢在温度为900～1100℃,应变速率为0.01～0.1 s-1条件下的变形行为为动态再结晶型.随着变形温度的上升或应变速率的下降,流变应力降低,同时小角晶界向大角晶界迁移,促进动态再结晶的发生.此外,试验钢的热变形激活能为396.44 kJ/mol,应变补偿本构方程的平均相对误差为5.4％,线性拟合相关系数为0.987,表明构建的应变补偿本构方程能够较为准确地预测试验钢在不同变形条件下的流变应力.
Abstract
Hot compression experiments were carried out on Fe-13Mn-4.4Al-0.64C-0.1Ti low density steel at deformation temperature of 900-1100℃ and strain rate of 0.01-0.1 s-1 by Gleeble-3500 thermal simulation testing machine.The strain-compensated constitutive equation was established on the basis of the traditional constitutive model.The hot deformation behavior of the experimental steel was studied by verification and analysis.The influence of deformation conditions on hot deformation behavior and microstructure evolution was studied by electron backscattering diffraction.The results show that the deformation behavior of the Fe-13Mn-4.4Al-0.64C-0.1Ti low density steel is dynamic recrystallization type at the temperature of 900-1100 ℃ and strain rate of 0.01-0.1 s-1.The flow stress decreases with the increase of deformation temperature or the decrease of strain rate.The migration of small angle boundary to large angle boundary promotes dynamic recrystallization.The hot deformation activation energy of the material is 396.44 kJ/mol.The relative absolute error of the strain-compensated constitutive equation is 5.4％,and the linear fitting correlation coefficient is 0.987,which indicates that the constructed strain-compensated constitutive equation can accurately predict the flow stress behavior of the low density steel under different deformation conditions.
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