Ti微合金化Q390高强钢热变形行为研究

通过单道次压缩实验,研究了屈服强度390 MPa级Ti微合金化高强钢的热变形行为,并建立了实验钢的变形抗力模型和动态再结晶数学模型.结果表明:随着变形温度的降低,变形抗力逐渐增大;随着应变速率的增大,应力-应变曲线由动态再结晶型转变为动态回复型.Q390钢的动态再结晶激活能为257.142 k J/mol.建立的高精度的数学模型可表征Ti微合金化Q390钢的高温变形行为.与常规成分体系相比,Ti微合金化成分设计的实验钢轧制时所需的轧制力较小,更容易发生动态再结晶,有利于奥氏体晶粒的细化,可有效地提高钢材强韧性.

Hot Deformation Behavior of Ti Microalloying Q390 High Strength Steel

The hot deformation behaviors of Ti microalloying high strength steel with yield strength of 390MPa grade (Q390 steel) were investigated by a single-pass compression test. A mathematical model for deformation resistance and dynamic recrystallization of the experimental steel was established. The results show that deformation resistance increases gradually with the decrease of deformation temperature. The feature of stress-strain curves changes from dynamic recrystallization character to dynamic recovery character as increasing the strain rate. The activation energy of dynamic recrystallization for Q390 steel is about 257.142kJ/mol. The mathematical model has been proved to study the hot deformation behavior for Ti microalloying Q390 steel very effectively. Compared with the Q390 steel with the conventional chemical composition， the rolling force of the steel after Ti microalloying is small and dynamic recrystallization occurs more easily， which can facilitate the refining of austenite grain and improve the strength and toughness of the steel more substantially.