A critical evaluation on efficacy of recrystallization vs. strain induced boundary migration in achieving grain boundary engineered microstructure in a Ni-base superalloy

Prithiv, T.S.; Bhuyan, P.; Pradhan, S.K.; Sarma, V. Subramanya; Mandal, Sumantra

doi:10.1016/j.actamat.2017.12.045

Cited by 138 publications

(27 citation statements)

References 61 publications

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“…However, annealing twins can resume the growth of stagnant grains during recrystallization with a low driving force according to the literature by Field et al [43], specifically for the GBE process. A typical thermo-mechanical procedure in terms of GBE is pre-strain by a low deformation plus annealing [35,36,44,45,46], as is the method used in this work. The low strain is not always enough to promote the migration of recrystallized front boundaries during annealing [47]; the twinning operation can then alter the misorientation of migrating front boundaries [43,48].…”

Section: Resultsmentioning

confidence: 99%

“…The low strain is not always enough to promote the migration of recrystallized front boundaries during annealing [47]; the twinning operation can then alter the misorientation of migrating front boundaries [43,48]. It is possible that the twinning operation produces a new front boundary with higher mobility, thereby promoting the process of recrystallization [46,48]. Therefore, twinning operations become “necessary incidents” to a large extent to motivate a full recrystallization route during GBE.…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of Grain Boundary Network and Improvement of Intergranular Cracking Resistance in 316L Stainless Steel after Grain Boundary Engineering

et al. 2019

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For understanding the improvement of intergranular stress corrosion cracking (IGSCC) propagation in grain boundary engineering (GBE)-processed metals exposed to a simulated pressurized water reactor (PWR) environment, characteristics of the grain boundary network of 316L stainless steel before and after GBE were investigated and compared, including proportions both in length and in number of ∑3n boundaries, sizes, and topology of grain clusters (or twin-related domains), and connectivity of random boundaries. The term through-view random boundary path (TRBP) was proposed to evaluate the random boundary connectivity. A TRBP is a chain of end-to-end connected crack-susceptible boundaries that passes through the entire mapped microstructure. The work provides the following key findings: (I) the length fraction of ∑3n boundaries was increased to approximately 75% after GBE, but the number fraction was only approximately 50%; (II) a connected non-twin boundary network still existed in the GBE sample due to the formation of grain clusters; (III) the GBE sample exhibited a higher resistance to IGSCC; and (IV) as the twin boundary fraction increased, the number of TRBPs decreased and the normalized length of the minimum TRBP increased monotonically, leading to a higher resistance to IGSCC.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Evaluation of Grain Boundary Network and Improvement of Intergranular Cracking Resistance in 316L Stainless Steel after Grain Boundary Engineering

et al. 2019

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“…GOS is the average difference in the orientation between different points in the grain. Deformed grains have a higher GOS compared to the recrystallized grains [24,25]. High-angle grain boundaries (HAGBs) were characterized as boundaries having a misorientation of more than 15 • .…”

Section: Methodsmentioning

confidence: 99%

The Influence of Segregation Bands and Hot Rolling on the Precipitation of Secondary Phases during Aging at 750 °C for Nickel Alloy 625

Malej

Medved²,

Batič

et al. 2019

Metals

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For Inconel 625, where the γ” and δ phases precipitate, the influence of prior hot rolling on the process is not well covered. The influence of segregation bands and prior hot rolling on the precipitation of secondary phases during aging at 750 °C for different times was investigated. Prior hot-rolling was conducted on a hot rolling mill at 1050 °C and 1150 °C with three different deformation levels. The hot rolled samples were aged at 750 °C for 1, 5, 25 and 125 h. The γ″ precipitated in both the deformed and recrystallized grains in the segregation bands containing a high concentration of niobium and molybdenum and a lower concentration of nickel, chromium and iron. The opposite was observed between the segregation bands where no γ″ precipitate was found. There was a smooth transition in the density and the size of the γ″ particles in the deformed grains at the border of the segregation bands, while a more complex transition occurred in the recrystallized grains. This occurred in the area where the average niobium concentration decreased from 4.5 to 2.7 wt. %, which influenced the mechanical properties.

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“…However, in the recrystallisation process, nuclei with different orientations are produced. The movement of the grain boundaries in the strain-induced boundary migration is towards the distorted regions due to the strain gradients generated [145]. Correspondingly, this would result in the increase of the size of one grain and the disappearance of the other grain.…”

Section: Formation and Effects Of Grain Boundary Migrationmentioning

confidence: 99%

“…These grains were separated by grain boundaries. As stated by some researchers, the straininduced boundary migration may, in fact, be considered as a type of recrystallisation process without the formation of new nuclei [143,145].…”

Section: Formation and Effects Of Grain Boundary Migrationmentioning

confidence: 99%

3D printing of shape memory alloy based smart structures

Khoo¹

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the opportunity to work on this interesting and challenging project. Their invaluable advice and continuous support throughout the course of his research are appreciated. The author is honoured to have the chance to work and learn under the supervisions of both Professors. The author would also like to thank Dr An Jia for his guidance on the writing of thesis and publications. His insightful suggestions have helped to refine the research from various perspectives. The author is grateful to the FYP students,

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A critical evaluation on efficacy of recrystallization vs. strain induced boundary migration in achieving grain boundary engineered microstructure in a Ni-base superalloy

Cited by 138 publications

References 61 publications

Evaluation of Grain Boundary Network and Improvement of Intergranular Cracking Resistance in 316L Stainless Steel after Grain Boundary Engineering

Evaluation of Grain Boundary Network and Improvement of Intergranular Cracking Resistance in 316L Stainless Steel after Grain Boundary Engineering

The Influence of Segregation Bands and Hot Rolling on the Precipitation of Secondary Phases during Aging at 750 °C for Nickel Alloy 625

3D printing of shape memory alloy based smart structures

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