微合金超高强度钢的热变形行为及流变应力模型

Flow Behavior and Dynamic Recrystallization Model for Ultra-high-strength Low Carbon Micro-alloyed Complex Phase Steel During Hot Deformation

采用Gleeble-3500热模拟试验机研究微合金超高强度复相钢(CP钢)在变形温度为900～1150℃、应变速率为0.1～10 s-1条件下的热变形行为,观察了不同变形条件下的晶粒组织。根据实验结果,建立了CP钢在热变形过程中的本构方程及动态再结晶过程的物理模型。实验结果表明,微合金元素钛的存在,明显抑制了动态再结晶的发生,提高了变形激活能,其值为439.09 kJ/mol。另外,热变形参数对最终的晶粒大小具有重要影响,随着再结晶变形温度的降低及应变速率的提高,晶粒尺寸明显减小。本构方程、动态再结晶模型能为科学设计和有效控制CP钢的热加工工艺提供依据。

The deformation behavior and evolution process of dynamic recrystallization for ultra-high-strength low carbon micro-alloyed complex phase steel（CP steel） were studied by isothermal compression test in the temperature range of 900～1150 ℃ and the strain rate range of 0.1～10 s-1.The effects of thermodynamic parameters on flow stress and grain size were analyzed.A constitutive relationship was proposed based on the Jonas equation.It is found that the high micro-alloyed elements of Ti restain the recrystallization behavior and improve apparent activity energy（439.09 kJ/mol）.The calculation results of the proposed model well agree with the experimental data.Therefore,the proposed model and results can lay the foundation of the quality control and process design of the rolling process for CP steel.