Post-dynamic recrystallization behavior of a powder metallurgy Ni-Co-Cr based superalloy under different deformation conditions

Qiao, Shi-chang; Wang, Yan; Lv, Liangxing; Tan, Gang; Cheng, Tianwei; He, Jingjun

doi:10.1016/j.jallcom.2021.162961

Cited by 6 publications

(8 citation statements)

References 37 publications

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“…Figure 6 quantifies the recrystallization fraction and the proportion of LAGBs, the relation of recrystallization fraction and the ratio of LAGBs exhibits similar patterns in other studies [ 7 , 11 , 30 ]. Annealing for the same time after deformation, as the strain rate increases from 0.001 to 0.01 s −1 , increases the recrystallization fraction from 10.5% to 20.2%.…”

Section: Resultssupporting

confidence: 78%

“…Further recrystallization occurs, for instance, meta-dynamic recrystallization (MDRX) originated from DRX grains and static recrystallization (SRX) merged by recrystallization nucleation and sub-grains rotation [ 9 , 10 ]. They are also collectively referred to as post-dynamic recrystallization (PDRX), that have a great influence on microstructural uniformity [ 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

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Strain Rate Dependence and Recrystallization Modeling for TC18 Alloy during Post-Deformation Annealing

Kong³

et al. 2023

Materials

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In this paper, the dependence of dynamic recrystallization (DRX) and post-dynamic recrystallization (PDRX) of TC18 alloy on strain rate within the range of 0.001 s−1~1 s−1 was investigated through isothermal compression and subsequent annealing in the single-phase region. Electron backscatter diffraction (EBSD) characterization was employed to quantify microstructure evolution and to reveal the recrystallization mechanism. At the thermo-deformation stage, the DRX fraction does not exceed 10% at different strain rates, due to the high stacking fault energy of the β phase. During the subsequent annealing process, the total recrystallization fraction increases from 10.5% to 79.6% with the strain rate increasing from 0.001 s−1 to 1 s−1. The variations in the geometrically necessary dislocation (GND) density before and after annealing exhibit a significant discrepancy with the increasing strain rate, indicating that the GND density is a key factor affecting the PDRX rate. The PDRX mechanisms, namely meta-dynamic recrystallization (MDRX), continuous static recrystallization (CSRX) and discontinuous static recrystallization (DSRX), were also revealed during the annealing process. A new kinetic model coupling DRX and PDRX was proposed to further describe the correlation between recrystallization and the strain rate during continuous deformation and annealing. This new model facilitates the prediction of recrystallization fraction during isothermal deformation and annealing of titanium alloys.

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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Strain Rate Dependence and Recrystallization Modeling for TC18 Alloy during Post-Deformation Annealing

Kong³

et al. 2023

Materials

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“…Where, σm are stress at interruption point; σy1 and σy2 refer to 2% offset yield stress during first-pass and the second-pass compression, respectively. Considerable subgrains are generated by dynamic softening during thermoforming, and then migrate via the subgrain boundaries to form new recrystallized grains [4]. During the holding stage, the subgrains can be regarded as the nuclei of MDRX and grow continuously by consuming the surrounding deformed grains, when the interruption strain exceeds the critical strain for DRX [13].…”

Section: Resultsmentioning

confidence: 99%

“…During the thermoforming stage, dynamic recrystallization (DRX) is the principal mechanism of softening behaviour, contributing to controlling the evolution of microstructure and reducing the deformation resistance [3]. The microstructure of the components is still evolving after deformation, which can be also regarded as post dynamic recrystallization (PDRX), suggesting that the effect of static softening behaviour on the ultimate microstructure and subsequent deformation process of the component is considerably imperative [4][5]. Therefore, it is indispensable to research the behaviour of static softening of GH4500 superalloy under different deformation conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The relationship of static softening fraction versus interval time at different deformation temperatures is plotted in figure 3(b). The softening fraction has attained about 0.3 at 1333 K for the interval time of 10 s, indicating commonly acknowledged fact that MDRX has no incubation period.Considerable subgrains are generated by dynamic softening during thermoforming, and then migrate via the subgrain boundaries to form new recrystallized grains[4]. During the holding stage, the subgrains can be regarded as the nuclei of MDRX and grow continuously by consuming the surrounding deformed grains, when the interruption strain exceeds the critical strain for DRX[13].…”

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confidence: 99%

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Model for characterizing static softening behaviour of GH4500 superalloy during two-pass thermal compression

Zhou

Wang

Zhu

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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In this work, the static softening behaviour of GH4500 superalloy during the two-pass thermal deformation was investigated via thermal-simulation compression experiments at the temperature range of 1293 K to 1373 K, strain rate range of 0.01 s−1 to 1 s−1 and interval time range of 0 s to 180 s. The metallographic structure acquired from optical microscope (OM) indicated that both static recovery (SRV) and post dynamic recrystallization (PDRX) would occur during the holding stage. Meanwhile, the influence of interval time, deformation temperatures and strain rates on static softening behaviour were revealed. The results showed that the softening effects principally induced by PDRX strengthened with the increase of the interval time, deformation temperatures and strain rates. To quantitatively describe the PDRX kinetic process of GH4500 superalloy, a model on grounds of Avrami kinetics was established to predict the PDRX softening fraction via eliminating the effect of static recovery. The predicted data of the PDRX softening fraction were well consistent with the experimental data, manifesting that the model could precisely evaluate the PDRX softening behaviour in the stage of inter-pass holding.

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Thermal Deformation Characteristics and Dynamic Recrystallization Mechanism of Incoloy 800H Alloy under Different Deformations

Jia,

Zhang,

Wang

et al. 2023

Adv Eng Mater

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Incoloy 800H alloy has excellent high‐temperature mechanical properties and broad application prospects. However, the dynamic recrystallization (DRX) behavior of this alloy at different deformations has been little studied. The thermal deformation characteristics and DRX mechanisms of Incoloy 800H alloy are studied by thermal compression tests. Quantitative analysis of grain size, DRX fraction, misorientation distribution, and twin boundaries under different deformation degrees is conducted using electron‐backscattered diffraction. Furthermore, the evolution characteristics of dislocations and grains are observed through transmission electron microscopy. It is found that the proportion of DRX improves with increasing deformation significantly. In the DRX process, discontinuous DRX (DDRX) is the main nucleation mechanism, while continuous DRX (CDRX) serves as an auxiliary nucleation mechanism. As the deformation increases, the CDRX + DDRX mechanisms can also be observed simultaneously in the high‐density dislocation region near the grain boundary. In addition, the ratio of ∑3 boundaries first decreases and then increases as the deformation increases. The initial twins gradually disappear due to the increase in deformation, and new twins are formed within the DRX grains. Twins can promote grain boundary bulging, provide more nucleation sites for DRX, and have a significant promoting effect on DRX.

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Post-dynamic recrystallization behavior of a powder metallurgy Ni-Co-Cr based superalloy under different deformation conditions

Cited by 6 publications

References 37 publications

Strain Rate Dependence and Recrystallization Modeling for TC18 Alloy during Post-Deformation Annealing

Strain Rate Dependence and Recrystallization Modeling for TC18 Alloy during Post-Deformation Annealing

Model for characterizing static softening behaviour of GH4500 superalloy during two-pass thermal compression

Thermal Deformation Characteristics and Dynamic Recrystallization Mechanism of Incoloy 800H Alloy under Different Deformations

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