基于机理法的考虑动态再结晶的黏塑性本构模型参数取值范围的确定

Determination of Parameter Value Domain for Macro-micro Coupled Viscoplastic Constitutive Model Consider Dynamic Recrystallization

宏微观耦合本构模型的参数识别往往通过反分析方法进行,为了使参数识别结果具有高的置信度,需要确定合适的参数取值范围。基于考虑动态再结晶的黏塑性本构模型的物理机理,提出该模型参数取值范围确定方法。为了提高模型参数识别结果的鲁棒性,对考虑动态再结晶的黏塑性模型进行修改,使模型中的稳态流动应力由Tanaka模型描述。根据模型构造机理,提出通过6步确定该模型参数取值范围的方法;对300M低合金钢进行不同温度、应变速率下的热变形试验,测试其流动应力-应变曲线、再结晶体积分数、再结晶晶粒尺寸、未再结晶晶粒尺寸、最大晶粒尺寸差,基于流动应力-应变曲线,提取再结晶区稳态流动应力和未再结晶区稳态流动应力。通过提出的方法并应用相应的算法,根据提取试验数据,确定模型的参数取值范围,为参数识别提供基础。

Parameter identification of macro-micro coupled constitutive model is generally taken through inverse analysis.To make the identified result with high confidence degree,the reasonable parameter value domain must be given.Based on the physical mechanism,a procedure is proposed.The procedure can be applied to determine the value domain of the parameter,which is involved in a macro-micro coupled constitutive model considering dynamic recrystallizaton.To improve the robustness of the parameter identification result,some parts of the model is revised and the steady flow stress is described by Tanaka model; a six-step method for the determination of the parameter value domain is given based on the physical mechanism involved in the model; the hot compression deformation of low alloy steel 300M is carried out under different combination of temperature and strain rate,the datum on true stress-strain curve,recrystallized volume fraction,recrystallized grain size,unrecrystallized grain size,maximum grain size difference are obtained,and the steady flow stress in unrecrystallized zone and recrystallized zone is determined,based on the true stress-strain curves.Based on the proposed procedure and the corresponding experimental data,the reasonable parameter ranges are given.The research provides a foundation for parameter identification of macro-micro coupled constitutive model.