42CrMo钢形变奥氏体的静态再结晶

Static recrystallization behaviors of deformed 42CrMo steel

利用双道次热压缩的方法,在Gleeble-1500热模拟实验机上研究42CrMo钢在高温变形道次间隔时间内的静态软化行为。讨论变形温度、应变速率、变形程度与初始奥氏体晶粒尺寸对其静态再结晶行为的影响。根据实验结果,建立42CrMo钢静态再结晶动力学模型,相应的静态再结晶激活能约为187.68kJ/mol。结果表明:变形程度对42CrMo钢的静态再结晶影响最大,变形温度和应变速率次之,初始奥氏体晶粒尺寸对其影响较小;在变形温度较低(850℃)时,随着道次间隔时间的增加,静态再结晶分数逐渐趋于稳定(约为0.4),这是因为在变形温度较低时,道次间不能发生完全的静态再结晶。在变形程度较小、道次间隔时间较短时,几乎不发生静态再结晶。将静态再结晶动力学模型的预测结果与实验结果进行比较,二者较吻合。

The static recrystallization behaviors in 42CrMo steel were investigated by two-pass hot compression tests on Gleeble-1500 thermo-simulation machine. The effects of deformation temperature, strain rate, deformation degree, and initial austenite grain size on the static recrystallization behaviors were studied. Based on experimental results, the kinetic equations for the static recrystallization behaviors of 42CrMo steel were proposed with the activation energy of 187.68 kJ/mol. The Results indicate that the effect of deformation degree on the static softening is significant, while that of the initial austenitic grain size is slight. With the increase of the inter-pass time, the static recrystallization fraction falls into a stable value （about 0.4） when the deformation temperature is 850℃. This indicates that the incomplete static recrystallization occurs when the deformation temperature is relatively low. A good agreement between the experimental and predicted results show that the proposed kinetic equations can give an accurate estimation of the static softening behaviors for hot deformed 42CrMo steel.