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An Investigation on Constitutive Relation and Dynamic Recrystallization of Hastelloy C-276 Alloy During Hot Deformation
Journal of Materials Engineering and Performance ( IF 2.3 ) Pub Date : 2020-09-04 , DOI: 10.1007/s11665-020-05057-5
Shengli Guo , Jiachen Liu , Bin Du , Shengpu Liu , Xiaoyu Zhang , Defu Li

Hot compression tests of Hastelloy C-276 alloy were conducted at the temperature ranging from 1000 to 1250 °C and strain rate ranging from 0.01 to 10 s−1. The constitutive relation and critical points of dynamic recrystallization (DRX) of the Hastelloy C-276 alloy were analyzed. The flow stress curves were corrected to tackle the problems of the influence of the adiabatic heating and friction. It was revealed that a five-order polynomial was suitable to solve the problem of the influence of strain. The critical strains of DRX could be expressed by the calculation from strain hardening rate as \( \varepsilon_{c} = 7.67 \times 10^{ - 4} Z^{0.144} {\text{and }}\varepsilon_{c} \approx 0.78\varepsilon_{p} \). Microstructural evolution revealed that the development of DRX of the alloy was complete at high temperature and low strain rate and the DRX grain size increased with the increase in temperature. The volume fraction of DRX was increased, and the grain size of DRX was also slightly increased with the increase in strain. The main nucleation mechanism of DRX was discontinuous dynamic recrystallization (DDRX), which was characterized by the grain boundary bowing nucleation mechanism coupled with the twinning-induced nucleation mechanism. Σ3 twins also contribute to the grain refinement and homogenization during hot deformation. The grains of C-276 alloy were refined significantly, and the microstructural homogeneity was improved effectively during hot deformation at high temperature and low strain rate. By choosing the suitable hot working processing parameters, the refinement and uniform distribution of grains of Hastelloy C-276 alloy could be obtained.



中文翻译:

哈氏合金C-276合金热变形本构关系及动态再结晶研究

Hastelloy C-276合金的热压缩试验在1000至1250°C的温度范围内以及0.01至10 s -1的应变速率下进行。分析了哈氏合金C-276合金的本构关系和动态再结晶的临界点。修正了流动应力曲线,以解决绝热加热和摩擦影响的问题。揭示了五阶多项式适合解决应变影响的问题。DRX的临界应变可以通过应变硬化率的计算表示为\(\ varepsilon_ {c} = 7.67 \ times 10 ^ {-4} Z ^ {0.144} {\ text {and}} \ varepsilon_ {c} \ approx 0.78 \ varepsilon_ {p} \)。显微组织演变表明,合金的DRX在高温和低应变速率下完全完成,DRX晶粒尺寸随温度的升高而增加。随着应变的增加,DRX的体积分数增加,DRX的晶粒尺寸也略有增加。DRX的主要成核机制是不连续动态重结晶(DDRX),其特征在于晶界弯曲成核机制与孪生诱导成核机制。Σ3双晶也有助于热变形过程中的晶粒细化和均质化。C-276合金的晶粒细化,在高温低应变率热变形过程中有效地改善了组织均匀性。

更新日期:2020-09-05
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