The dynamic recrystallization behavior of Mn-Nb-Cu-B low carbon bainite steel was investigated via a single-pass reduction test on a Gleeble-1500 thermo-machine simulator at the temperatures ranging from 1 000 to 1 150 ? and strain rates from 0.01 to 0.1 s-1. The equation describing the hot working process was also obtained. The critical condition of dynamic recrystallization was determined by sing the working hardening rate-strain curves of this bainite steel dynamic recrystallization critical strain model and Peak strain model were obtained. The recrystallized fraction at various deformation conditions was measured by using s-e curve and the dynamic recrystallization kinetic model was set up by using the recrystallized fraction of this low carbon bainite steel. The results show that dynamic recrystallization occurs during deformation. As the deformation temperature increases and strain rate decreases, the critical strain of dynamic recrystallization decreases, and softening caused by dynamic recrystallization is more obvious. The activation energy for hot deformation of this kind of bainite steel is calculated to be 328 kJ/mol by regression analysis. The average value of ec/ep is 0.63 during dynamic recrystallization.%利用Gleeble-1500热模拟试验机对Mn-Nb-Cu-B低碳贝氏体钢进行单道次压缩实验,研究其在温度为1 000～1 150℃和应变速率为0.01～0.1 s-1条件下的动态再结晶行为.通过加工硬化率和应变的关系曲线确定该贝氏体钢发生动态再结晶的临界条件,并建立动态再结晶临界应变模型和峰值应变模型.根据应力-应变曲线数据确定不同变形条件下该贝氏体钢的动态再结晶的体积分数,并利用该体积分数建立动态再结晶动力学模型.研究结果表明:Mn-Nb-Cu-B低碳贝氏体钢高温变形存在动态再结晶现象,且随着变形温度的升高,应变速率的降低,动态再结晶临界应变量减小,更容易发生动态再结晶.采用回归法确定该贝氏体钢的动态再结晶激活能为328 kJ/mol,并获得该贝氏体钢的热加工方程.该低碳贝氏体钢发生动态再结晶的临界应变与峰值应变的平均比值εc/εp为0.63.
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