Hot deformation behavior and flow stress modeling of a Ni-based superalloy
Hot deformation behavior and flow stress modeling of a Ni-based superalloy
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DOI：
10.1016/j.matchar.2019.109915
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发表时间：
2019-11-01
影响因子：
4.7
通讯作者：
Hawk, Jeffrey A.
中科院分区：
文献类型：
--
作者：
Detrois, Martin;Antonov, Stoichko;Hawk, Jeffrey A.
采用Gleeble系统研究了一种新型镍基高温合金在1050 ~ 1210 ℃、0.001 ~ 0.1 s（-1）应变速率下的等温压缩变形行为。流动应力曲线和电子背散射衍射图进行了实验，以确定在变形过程中的各种流动机制。在低于1130 ℃的温度下的变形呈现出强的加工硬化，在动态软化期间具有有限的恢复，导致部分再结晶的微观结构。将变形温度提高到1130摄氏度或更高，增强了位错和晶界迁移的驱动力，从而使动态回复（DRV）和动态再结晶（DRX）机制能够更好地运行。在此温度下，应变速率的影响在变形过程中更为明显。应变速率从0.001 s（-1）增加到0.1 s（-1）导致主要软化机制从DRY转变为DRX。采用Zener-Hollomon参数建立了流变应力模型，得到了合金热变形的激活能和本构方程。流动行为的强烈变化影响了流动应力模型的准确性，因此，该模型交替用于识别与各种流动状态相关的变形参数。在这样做的过程中，激活能和其他方程常数获得实验观察到的每个变形机制。
The deformation behavior of a novel Ni-based superalloy was investigated using isothermal compression on a Gleeble system at temperatures between 1050 and 1210 degrees C with strain rates between 0.001 and 0.1 s(-1). Flow-stress curves and electron backscatter diffraction maps were employed to experimentally identify the various flow mechanisms operative during deformation. Deformation at temperatures below 1130 degrees C presented strong work hardening with limited restoration during dynamic softening leading to partially recrystallized microstructures. Increasing the deformation temperature to and above 1130 degrees C enhanced the driving force for dislocation and grain boundary mobility thereby enabling dynamic recovery (DRV) and dynamic recrystallization (DRX) mechanisms to better operate. The influence of the strain rate was more evident during deformation at these temperatures. Increasing the strain rate from 0.001 s(-1) to 0.1 s(-1) resulted in a transition in dominant softening mechanism from DRY to DRX. Flow stress modeling using the Zener-Hollomon parameter was performed to obtain the activation energy and the constitutive equation for hot deformation of the alloy. Strong changes in flow behavior affected the accuracy of the flow stress model, and thus, the model was used alternatively to identify deformation parameters associated with various flow regimes. In doing so, the activation energy and the other equation constants were obtained for each deformation mechanism observed experimentally.