Methods and mechanisms for uniformly refining deformed mixed and coarse grains inside a solution-treated Ni-based superalloy by two-stage heat treatment

Wang, Guan-Qiang; Chen, Mingsong; Li, Hongbin; Lin, Y.C.; Zeng, Weidong; Ma, Yan-Yong

doi:10.1016/j.jmst.2020.11.030

Cited by 49 publications

(12 citation statements)

References 67 publications

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“…The annealing times of the CRT are 10, 20 and 30 min. Moreover, as reported by Wang et al [36], after aging at 900°C for 12 h, the recrystallization rate is also slow when the annealing temperature is 980°C. Thus, the temperature for the primary high-temperature annealing stage of CRT can be defined as higher than 1000°C, while the temperature for the subsequent relatively low-temperature annealing stage of CRT can be defined as lower than 980°C.…”

Section: Materials and Experimentsmentioning

confidence: 52%

“…The growth of recrystallized grain in the direction of the intragranular is only hindered by the dissolving phase. Thus, some recrystallized grains grow to a large size in the direction of intragranular [36]. The mixed annealed grain microstructure will be obtained after a long annealing time, as displayed in Figure 1(b).…”

Section: A New Annealing Methods and Its Design Principlesmentioning

confidence: 97%

“…Generally, the high thermal energy can significantly promote both recrystallization nucleation and grain growth. When the annealing temperature is high, although the SRX nucleation rate is large, all the recrystallized grains will rapidly grow to a large size under the high thermal energy [36]. The coarse and uniform annealed grain microstructure will be obtained after a short annealing time, as shown in Figure 1(a).…”

Section: A New Annealing Methods and Its Design Principlesmentioning

confidence: 99%

“…However, there is a contradiction that the increase of static recrystallization (SRX) nucleation rate needs to raise the annealing temperature while the decrease of grain growth rate needs to reduce the annealing temperature during traditional isothermal recrystallization annealing treatment. It is not easy to obtain the uniform and fine grain by isothermal annealing treatments [36,37] because increasing the SRX nucleation rate and decreasing the grain growth rate are the main ways to obtain uniform and fine grain microstructure. Hence, it is necessary to explore a new method to uniformly refine deformed mixed grains.…”

Section: Introductionmentioning

confidence: 99%

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A novel annealing method to uniformly refine deformed mixed grain microstructure of a solution-treated Ni-based superalloy

Wang

Chen

Lin

et al. 2021

Sci. China Technol. Sci.

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Increasing static recrystallization (SRX) nucleation rate and decreasing grain growth rate are the main ways to obtain uniform and fine grain microstructure by annealing treatment. However, it is contradictory to raise the SRX nucleation rate and reduce grain growth rate during isothermal annealing treatment. This is because the increase of the SRX nucleation rate needs to raise annealing temperature, while the decline of grain growth rate needs to reduce the annealing temperature. To solve the contradiction, a novel method named cooling recrystallization annealing treatment (CRT) is designed and verified. For the CRT, the relatively high annealing temperature in the primary stage can promote SRX nucleation, and the gradually decreased annealing temperature can reduce the growth rate of SRX grains. Besides, an aged treatment is first carried out to precipitate high content of the δ phase before the CRT. Enough δ phases not only provide large numbers of sites for SRX nucleation but also limit the grain growth due to the pinning effect, especially in the primary high-temperature stage. The results show that the novel method can refine deformed mixed grain microstructure well when the suitable cooling rate, start and final recrystallization annealing temperatures are employed. The deformed mixed grain can be uniformly refined to an average size of 8.26 µm with the route of 900°C×12 h+1020°C→970°C×20 min.

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Section: Materials and Experimentsmentioning

confidence: 52%

Section: A New Annealing Methods and Its Design Principlesmentioning

confidence: 97%

Section: A New Annealing Methods and Its Design Principlesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A novel annealing method to uniformly refine deformed mixed grain microstructure of a solution-treated Ni-based superalloy

Wang

Chen

Lin

et al. 2021

Sci. China Technol. Sci.

View full text Add to dashboard Cite

show abstract

“…During tensile deformation, the resistance to slip is larger, and then the strength improves. On the other hand, there are some δ phases in the sample, and it results in a decrease in the fraction of strengthening γ′′ phase after the strengthening heat treatment [ 49 ]. Compared to the hot-upsetting sample (case 1), the fraction of δ phase for annealed samples (cases 3, 4, and 5) is larger.…”

Section: Results and Analysismentioning

confidence: 99%

Effects of Double-Stage Annealing Parameters on Tensile Mechanical Properties of Initial Aging Deformed GH4169 Superalloy

et al. 2021

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This study takes large size samples after hot-upsetting as research objects and aims to investigate the optimization double-stage annealing parameters for improving the mechanical properties of hot-upsetting samples. The double-stage annealing treatments and uniaxial tensile tests for hot-upsetting GH4169 superalloy were finished firstly. Then, the fracture mode was also studied. The results show that the strength of hot-upsetting GH4169 superalloy can be improved by the double-stage annealing treatment, but the effect of annealing parameters on the elongation of GH4169 alloy at high temperature and room temperature is not significant. The fracture mode of annealed samples at high-temperature and room-temperature tensile tests is a mixture of shear fracture and quasi-cleavage fracture while that of hot-upsetting sample is a shear fracture. The macroscopic expressions for the two fracture modes belong to ductile fracture. Moreover, it is also found that the improvement of strength by the double-stage annealing treatment is greater than the single-stage annealing treatment. This is because the homogeneity of grains plays an important role in the improvement of strength for GH4169 superalloy when the average grain size is similar. Based on a comprehensive consideration, the optimal annealing route is determined as 900 °C × 9–12 h(water cooling) + 980 °C × 60 min(water cooling).

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Effects of Deformation Processing Parameters on the Microstructure Evolution and Microhardness of GH4169 Superalloy during Annealing Treatment

et al. 2021

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Effects of deformation processing parameters on the microstructural evolution and microhardness of deformed samples during annealing treatment were analyzed. The results show that the initial aging time has the greatest influence on the refinement of annealed grain compared with other processing parameters. This attributes to more δ phases precipitating with the improving initial aging time. The high content of δ phase hinders the quick dynamic recrystallization (DRX) grain growth during annealing. Thus, the high strain rate helps to refine deformed grain by annealing treatment due to a high content of δ phase retained after deformation. Additionally, the massive appearance of recrystallized nuclei/grains also hinders adjacent grain growth. The appearance of many DRX nuclei at high deformation temperature or true strain will cause the fine annealed grain, although the dissolution of δ phase is enhanced. Thus, the grain deformed at 950–1010 °C can be refined to 11–14 μm during annealing. Furthermore, the high true strain is beneficial to obtain fine and homogeneous microstructure during annealing because the high deformation energy promotes static recrystallization (SRX) nucleation. Besides, the microhardness of GH4169 superalloy depends on the grain size and retained content of δ phase due to the fine‐grain and γ″ phase strengthening.

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Methods and mechanisms for uniformly refining deformed mixed and coarse grains inside a solution-treated Ni-based superalloy by two-stage heat treatment

Cited by 49 publications

References 67 publications

A novel annealing method to uniformly refine deformed mixed grain microstructure of a solution-treated Ni-based superalloy

A novel annealing method to uniformly refine deformed mixed grain microstructure of a solution-treated Ni-based superalloy

Effects of Double-Stage Annealing Parameters on Tensile Mechanical Properties of Initial Aging Deformed GH4169 Superalloy

Effects of Deformation Processing Parameters on the Microstructure Evolution and Microhardness of GH4169 Superalloy during Annealing Treatment

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