采用Gleeble-3500热模拟实验机, 对铌微合金钢Q345B进行热压缩实验. 基于所获实验结果, 充分考虑了热变形工艺参数(应变速率和变形温度)和动态软化机制(动态回复和动态再结晶)对流变应力的影响, 建立了一种考虑动态软化机制影响的高温变形显式本构模型, 给出了本构方程求解的方法, 确定了模型中与工艺参数相关的主要参数的定量关系式; 其主要特点是能够较准确地描述材料在高应力区域的动态回复软化阶段、动态再结晶软化阶段和稳定流变阶段的应力-应变关系. 模型验证表明, 所建立模型预测出的流变曲线与实验结果吻合良好.
The flow stress curves of Nb microalloyed steel Q345B during hot compression deformation were obtained on Gleeble-3500 thermo-simulation machine. Based on the experimental results, the constitutive model of Nb microalloyed steel during high temperature deformation was established to describe the stress-strain relationship during dynamic softening (dynamic recovery and dynamic recrystallization) and in the steady flow state, in which the influences of the thermal deformation parameters (strain rate and deformation temperature) and dynamic softening mechanism (dynamic recovery and dynamic recrystallization) on the flow stress were considered. A method was provided to solve constitutive equation and establish the mathematic expressions of the correlation coefficients. It is shown that the predicted results by the model are in good agreement with the experimental ones.
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