新型低碳含铌热轧H型钢的热变形行为

利用热压缩试验、显微组织分析等手段,研究了一种新型低碳含铌热轧H型钢在1000~1200 ℃变形温度和0.1~5 s^-1应变速率下的热变形行为。分析了变形参数对试验钢微观组织的影响,建立了耦合应变量因素的改进型本构方程,并采用临界比的临界应变模型对发生动态再结晶的临界应变值进行了预测。结果表明:较低应变速率和变形温度下,试验钢的原始奥氏体组织更均匀且平均晶粒尺寸更小;应变速率的升高不利于动态再结晶的发生。发生动态再结晶的临界应变与峰值应变的关系为ε_c/ε_p=0.47。与耦合应变量因素有关的本构方程和临界应变预测模型能较准确地预测各变形温度下低碳含铌热轧H型钢的流变应力和动态再结晶临界应变值。

Thermal deformation behavior of a low carbon hot-rolled H-beam steel containing niobium

Thermal deformation behavior at temperature between 1000-1200 ℃ with strain rate of 0.1-5 s^-1 of a new low-carbon hot-rolled H-beam steel containing niobium was studied by means of hot compression experiment and microstructure analysis. The microstructure of the tested steel affected by deformation parameters was analyzed. At the same time, an improved constitutive equation of coupled strain factor was established, and the critical strain model with critical ratio was adopted to predict the critical strain value for dynamic recrystallization. The results show that the original austenite structure is more uniform and the average grain is smaller at lower strain rate and deformation temperature. And the increase of strain rate is not conducive to the occurrence of dynamic recrystallization. The relationship between the critical strain for dynamic recrystallization and the peak strain is ε_c/ε_p=0.47. The constitutive equation related to the coupled strain factor and critical strain prediction model can accurately predict the flow stress and critical strain values of low-carbon niobium-containing hot-rolled H-beam steel at different deformation temperatures.