Gao Fei, Gao Zilong, Zhu Qiyong, Liu Zhenyu
School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
Key Laboratory of Lightweight Structural Materials Liaoning Province, Northeastern University, Shenyang 110819, China.
Materials (Basel). 2021 Sep 3;14(17):5022. doi: 10.3390/ma14175022.
The deformation behavior for highly purified Fe-17Cr alloy was investigated at 7001000 °C and 0.510 s. The microstructure evolution and corresponding mechanism during deformation were studied in-depth, using electron backscattering diffraction, transmission electron microscopy and precession electron diffraction. During deformation, dynamic recrystallization (DRX) occurred, along with extensive dynamic recovery, and the active DRX mechanism depended on deformation conditions. At higher Zener-Hollomon parameter ( ≥ 5.93 × 10 s), the development of the shear band was promoted, and then continuous DRX was induced by the formation and intersection shear band. At lower Zener-Hollomon parameter ( ≤ 3.10 × 10 s), the nucleation of the new grain was attributed to the combination of continuous DRX by uniform increase in misorientation between subgrains and discontinuous DRX by grain boundary bulging, and with increasing temperature, the effect of the former became weaker, whereas the effect of the latter became stronger. The DRX grain size increased with the temperature. For alleviating ridging, it seems advantageous to activate the continuous DRX induced by shear band through hot deformation with higher . In addition, the modified Johnson-Cook and Arrhenius-type models by conventional way were developed, and the modified Johnson-Cook model was developed, using the proposed way, by considering strain dependency of the material parameters. The Arrhenius-type model was also modified by using the proposed way, through distinguishing stress levels for acquiring partial parameter and through employing peak stress to determine the activation energy and considering strain dependency of only other parameters for compensating strain. According to our comparative analyses, the modified Arrhenius-type model by the proposed approach, which is suggested to model hot-deformation behavior for metals having only ferrite, could offer a more accurate prediction of flow behavior as compared to other developed models.
研究了高纯Fe-17Cr合金在7001000 °C和0.510 s条件下的变形行为。利用电子背散射衍射、透射电子显微镜和进动电子衍射深入研究了变形过程中的微观组织演变及相应机制。变形过程中发生了动态再结晶（DRX），同时伴随着广泛的动态回复，且活跃的DRX机制取决于变形条件。在较高的齐纳-霍洛蒙参数（≥5.93×10 s）下，促进了剪切带的发展，随后由形成和相交的剪切带诱导连续DRX。在较低的齐纳-霍洛蒙参数（≤3.10×10 s）下，新晶粒的形核归因于亚晶粒间取向差均匀增加导致的连续DRX和晶界鼓胀导致的不连续DRX的结合，并且随着温度升高，前者的作用变弱，而后者的作用变强。DRX晶粒尺寸随温度增加。为了减轻起皱，通过较高的热变形激活由剪切带诱导的连续DRX似乎是有利的。此外，通过常规方法建立了改进的约翰逊-库克模型和阿累尼乌斯型模型，通过考虑材料参数的应变依赖性，采用所提出的方法建立了改进的约翰逊-库克模型。通过区分获取部分参数的应力水平并采用峰值应力来确定激活能，同时仅考虑其他参数的应变依赖性以补偿应变，采用所提出的方法对阿累尼乌斯型模型进行了修正。根据我们的比较分析，与其他已开发的模型相比，所提出方法修正的阿累尼乌斯型模型对仅具有铁素体的金属的热变形行为建模时，能够更准确地预测流变行为。
