Study of dynamic recrystallization in a Ni-based superalloy by experiments and cellular automaton model
Study of dynamic recrystallization in a Ni-based superalloy by experiments and cellular automaton model
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镍基高温合金动态再结晶的实验和元胞自动机模型研究
DOI：
10.1016/j.msea.2014.12.092
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发表时间：
2015-02-25
期刊：
影响因子：
6.4
通讯作者：
Chen, Ming-Song
中科院分区：
文献类型：
--
作者：
Liu, Yan-Xing;Lin, Y. C.;Chen, Ming-Song
通过热压缩试验，研究了一种典型镍基高温合金在应变速率为0.001 ~ 1 s（-1）、变形温度为920-1040 ℃条件下的热压缩行为。结果表明，动态再结晶是该合金热变形软化的主要机制。变形温度和应变速率对动态再结晶晶粒尺寸有显著影响。根据实验结果，建立了动态再结晶晶粒尺寸与稳态流变应力之间的逆幂律关系式。建立了具有概率状态切换的元胞自动机模型，模拟了该合金的动态再结晶行为。该模型能较好地预测合金的流变应力和动态再结晶晶粒尺寸。在此基础上，研究了动态再结晶动力学以及平均晶粒尺寸和晶界分数的演化规律。模拟结果表明，动态再结晶初始为不均匀的，随着动态再结晶体积分数的增加，动态再结晶逐渐趋于均匀。随着应变的增加，平均晶粒尺寸减小，晶界分数增加。此外，当变形处于稳定状态时，平均晶粒尺寸和晶界分数保持相对恒定。(C)2014爱思唯尔有限公司版权所有。
The hot compressive behaviors of a typical Ni-based superalloy are investigated by hot compression tests under the strain rates of 0.001-1 s(-1) and deformation temperatures of 920-1040 degrees C. It is found that the dynamic recrystallization is the main softening mechanism for the studied superalloy during hot deformation. The deformation temperature and strain rate have a significant influence on the dynamically recrystallized grain size. Based on the experimental results, an inverse power law equation is established to describe the relationship between the dynamically recrystallized grain size and the steady-state flow stress. A cellular automaton model with probabilistic state switches is established to simulate the dynamic recrystallization behaviors of the studied superalloy. The flow stress and the dynamically recrystallized grain size can be well predicted by the established model. Then, the dynamic recrystallization kinetic and the evolutions of the average grain size and grain boundary fraction are studied based on the simulated results. The simulated results show that the dynamic recrystallization is initially heterogeneous, and gradually becomes homogeneous with the increase of the volume fraction of dynamic recrystallization. With the increase of strain, the average grain size decreases, while the grain boundary fraction increases. Furthermore, the average grain size and the grain boundary fraction remain relatively constant when the deformation is under a steady state. (C) 2014 Elsevier B.V. All rights reserved.