高强钢筋热压缩过程的本构分析及有限元模拟

为了研究Nb/V微合金化钢筋的热变形行为,采用 Gleeble-3500热模拟机对Nb和Nb/V微合金化的20MnSi钢进行单轴热压缩试验。通过对其不同形变条件(变形温度和应变速率)下的真应力-应变曲线进行分析,建立可以表征20MnSiNb和20MnSiNbV钢应力、应变、应变速率和温度四者关系的本构方程,并将该本构方程应用于有限元分析软件DEFORM 3D的材料模块中,对试验钢的热压缩过程进行数值模拟。结果表明,2种试验钢的热压缩过程均呈现了明显的动态再结晶特征,Nb或Nb/V微合金化均导致20MnSi钢的热变形激活能增加;有限元模拟表明压缩试样存在应变场和温度场分布不均匀现象,其中试样芯部相对于其他区域始终处于高应变、高应变速率和高形变温度的状态。在实际生产和研究中,对试样不同区域组织和性能的预测可参考模拟结果,分别进行探究。

Constitutive analysis and finite element simulation of high-strength rebar during hot compression process

Abstract: In order to study the hot deformation behavior of Nb/V microalloyed steel bars, the uniaxial hot compressions experiment of Nb and Nb/V microalloyed 20MnSi steel were carried out by Gleeble-3500 thermal simulator. Based on the true stress-strain curve under different deformation conditions(temperature and strain rate), the constitutive equation that can characterize the relationship between stress, strain, strain rate and temperature of 20MnSiNb and 20MnSiNbV steels were established, and the constitutive equation was applied to the material module of the finite element software DEFORM 3D to simulate the hot compression process of experimental steels. Research shows that the hot compression deformation process of the two alloys exhibits obvious dynamic recrystallization characteristics, and the addition of Nb or Nb/V microalloying elements leads to an increase in the hot deformation activation energy of 20MnSi steel. The simulation results show that there is an uneven distribution of the strain field and temperature field in the compressed sample. The core of the compressed sample is always in a state of high strain, high strain rate and high deformation temperature relative to other regions. In actual production and research, the prediction of the structure and performance for different regions of the sample should refer to the simulation results and explore separately.