Nb对微合金非调质钢热加工过程的影响

Effect of Niobium on Microstructure of Micro-alloyed Steel During Hot Deformation Process

通过Gleeble-3800热模拟试验机模拟了微合金非调质钢38MnVS和C38N2在变形温度950～1150℃,应变速率0.1～10s-1,变形量为60%的单道次压缩试验。结果表明:变形温度越高,应变速率越低,越易发生再结晶;变形温度越低,应变速率越高,越易产生更加细小的再结晶晶粒尺寸;试验钢C38N2的动态再结晶变形激活能较试验钢38MnVS的高,这是因为Nb具有拖曳阻止再结晶的作用,推迟了试验钢C38N2的动态再结晶过程。微合金元素Nb的添加,具有细化晶粒,降低珠光体层片间距及扩宽热加工区间的作用。

The micro-alloying forging steel C38N2 and 38MnVS was compressed by Gleeble-3800 thermo-mechanical simulator at high temperature （950-1150 ℃） under strain rate of 0.1 s-1 to 10s-1. Based on the analysis of the curves of the flow stress and the microstructure, the effects of thermo-mechanical treatment parameters on the dynamic recrystallization （DRX） behavior of the steel were investigated. The results show that the addition of Nb produces a retardation of dynamic recrystallization and grain growth because of the increased active energy of dynamic recrystallization due to the solid solution drawing and precipitate pinning. In addition, the results show that the deformation conditions （temperature, strain and strain rate） can affect the dynamic recrystallization kinetics as well. The addition of Nb produces a retardation of dynamic recrystallization, grain growth and pearlite formation in micro-alloyed steel, thus in tttm refines the pearlite grain size, reduces lamellar pearlite spacing and widens the thermal processing interval during transformation process.