摘要
利用Thermecmastor-Z型热模拟试验机,结合金相显微镜(OM)、扫描电镜(SEM)、维氏硬度计等,系统研究了奥氏体区变形对50CrV4钢连续冷却相变和等温相变规律的影响。建立了试验钢动态CCT曲线。研究结果表明,奥氏体变形能促进连续冷却转变过程中铁素体-珠光体、贝氏体转变,但亦可提高奥氏体的机械稳定性,进而抑制马氏体转变,Ms点由331.6℃(奥氏体未变形)降低至291℃(950℃下变形50%+890℃下变形50%,变形速率均为5s-1,变形后冷速为20℃/s)。当轧后冷速小于0.5℃/s时,试验钢中可获得铁素体+珠光体组织。此外,在研究不同变形量对试验钢等温相变规律影响时发现,650℃等温时,试验钢中发生铁素体-珠光体相变。随着变形量的增加(由30%增加至50%),其等温相变动力学加快(相变完成时间由197.6s减小至136.5s),铁素体体晶粒尺寸、珠光体片层间距减小,硬度增加。
The effect of austenite deformation on the continuous cooling phase transformation behavior and isothermal phase transformation behavior of 50CrV4 steel were systematically investigated by using of Thermecmastor-Z thermal simulation testing machine, OM, SEM and Vickers hardness tester. The dynamic CCT curve of 50CrV4 steel was established. The results show that austenite deformation can promote ferrite-pearlite and bainite transformation during the continuous cool- ing process. And it also enhances the mechanical stability of austenite and inhibites the martensite transformation. While the Ms value decreases from 331.6 ℃ （Austenite non-deformation） to 291 ℃ （The specimens underwent 50% engineering strain at 950 ℃ ＋ 50% engineering strain at 890 ℃, the strain rate is 5 s-1 , and the cooling rate after deformation is 20 ℃/s. ）. When the cooling rate is lower than 0. 5 ℃/s, the microstructure of ferrite and pearlite can be obtained in the ex- perimental steel. Furthermore, the study on the effect of austenite deformation on isothermal phase transformation of tested steel shows that when the tested steel is held at 650 ℃, the transformation from austenite to ferrite and pearlite takes place. And when the deformation increases from 30% to 50%, the isothermal phase transformation kinetics acceler- ate （The phase transformation completion time decreases from 197. 6 s to 136.5 s）, the grain size of ferrite and the interla- mellar spacing of pearlite decreases, the hardness increases.
出处
《钢铁研究学报》
CAS
CSCD
北大核心
2017年第5期411-419,共9页
Journal of Iron and Steel Research
基金
中国博士后科学基金资助项目(2014M562072)
