Microstructural and processing factors influencing the formation of annealing twins

Cahoon, J. R.; Li, Qiangyong; Richards, N.L.

doi:10.1016/j.msea.2009.07.021

Cited by 65 publications

(38 citation statements)

References 25 publications

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“…calculate the overall twin density via Equation (1). There is a strong inverse correlation of the twin density with the average grain size; similar trends have already been reported in the literature for different FCC metals and alloys [7,[15][16][17][18]. According to Pande [18], the annealing twin evolution depends on the grain boundary migration driving force and on the grain boundary migration distance (and therefore, on grain size).…”

Section: Experimental Results and Discussion Of The Underlying Mechansupporting

confidence: 77%

“…The total twin boundary length and the surface of the overall microstructure are used to calculate the overall twin density via Equation (1). There is a strong inverse correlation of the twin density with the average grain size; similar trends have already been reported in the literature for different FCC metals and alloys [7,[15][16][17][18]. calculate the overall twin density via Equation (1).…”

Section: Experimental Results and Discussion Of The Underlying Mechansupporting

confidence: 72%

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Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

Jin

Bernacki

Agnoli

et al. 2015

Metals

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Abstract:Grain growth experiments were performed on Inconel™ 718 to investigate the possible correlation of the annealing twin density with grain size and with annealing temperature. Those experiments were conducted at different temperatures in the δ supersolvus domain and under such conditions that only capillarity forces were involved in the grain boundary migration process. In the investigated range, there is a strong inverse correlation of the twin density with the average grain size. On the other hand, the twin density at a given average grain size is not sensitive to annealing temperature. Consistent with previous results for pure nickel, the twin density evolution in Inconel™ 718 is likely to be mainly controlled by the propagation of the pre-existing twins of the growing grains; i.e., the largest ones of the initial microstructure. Almost no new twin boundaries are created during the grain growth process itself. Therefore, the twin density at a given average grain size is mainly dependent on the twin density in the largest grains of the initial microstructure and independent of the temperature at which grains grow. Based on the observations, a mean field model is proposed to predict annealing twin density as a function of grain size during grain growth.

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Section: Experimental Results and Discussion Of The Underlying Mechansupporting

confidence: 77%

Section: Experimental Results and Discussion Of The Underlying Mechansupporting

confidence: 72%

Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

Jin

Bernacki

Agnoli

et al. 2015

Metals

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“…This suggests that the development of annealing twins slows down as the recrystallized grains coarsen. Similar results were obtained in other studies on the annealing twin development [38][39][40]. A rapid increase in twin density was observed during the recrystallization development [40], whereas subsequent grain growth was accompanied by an apparent decrease in the twin density [39].…”

supporting

confidence: 89%

“…, which is consistent with experimental data for the change in the twin density during grain growth [39,42,44]. The number fraction of Σ3 n CSL boundaries (F CSL ) in the annealed microstructure can be estimated by a ratio of the number of Σ3 n CSL boundaries in a grain to the total number of boundaries per grain: Philosophical Magazine 4191…”

supporting

confidence: 83%

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Tikhonova

Kuzminova

Fang

et al. 2014

Philosophical Magazine

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The effect of processing and annealing temperatures on the grain boundary characters in the ultrafine-grained structure of a 304-type austenitic stainless steel was studied. An S304H steel was subjected to multidirectional forging (MDF) at 500-800°C to total strains of~4, followed by annealing at 800-1,000°C for 30 min. The MDF resulted in the formation of ultrafine-grained microstructures with mean grain sizes of 0.28-0.85 μm depending on the processing temperature. The annealing behaviour of the ultrafine-grained steel was characterized by the development of continuous post-dynamic recrystallization including a rapid recovery followed by a gradual grain growth. The post-dynamically recrystallized grain size depended on both the deformation temperature and the annealing temperature. The recrystallization kinetics was reduced with an increase in the temperature of the preceding deformation. The grain growth during post-dynamic recrystallization was accompanied by an increase in the fraction of Σ3 n CSL boundaries, which was defined by a relative change in the grain size, i.e. a ratio of the annealed grain size to that evolved by preceding warm working (D/D 0 ). The fraction of Σ3 n CSL boundaries sharply rose to approximately 0.5 in the range of D/D 0 from 1 to 5, which can be considered as early stage of continuous post-dynamic recrystallization. Then, the rate of increase in the fraction of Σ3 n CSL boundaries slowed down significantly in the range of D/D 0 > 5. A fivefold increase in the grain size by annealing is a necessary condition to obtain approximately 50% Σ3 n CSL boundaries in the recrystallized microstructure.

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“…From the experimental results, constitutive models commonly used for describing the formation of twin boundaries in polycrystalline materials were used to quantify the density and length fraction of Σ3 boundaries as a function of the grain size [63]. The models were further modified to account for the influence of deformation based on the magnitude of strain energy [59] similar to the work of Li et al on cold rolling [64,65]. The resulting density and length fraction of Σ3 boundaries as a function of the average grain size are expressed in Eqs.…”

Section: Grain Boundary Engineeringmentioning

confidence: 99%

Tailoring the Properties of a Ni-Based Superalloy via Modification of the Forging Process: an ICME Approach to Fatigue Performance

Detrois

Rotella

Hardy

et al. 2017

Integr Mater Manuf Innov

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Traditionally, material design and property modifications are usually associated with compositional changes. Yet, subtle changes in the manufacturing process parameters can also have a dramatic effect on the resulting material properties. In this work, an integrated computational materials engineering (ICME) framework is adopted to tailor the fatigue performance of a Ni-based superalloy, RR1000. An existing fatigue model is used to identify microstructural features that promote enhanced fatigue life, namely a uniform, fine grain size distribution, random orientation, a distinct grain boundary distribution (specifically high twin boundary density and limited low-angle grain boundaries). A deformation mechanism map and process models for grain boundary engineering of RR1000 are used to identify the optimal thermo-mechanical processing parameters to realize these desirable microstructural features. For validation, small-scale forgings of RR1000 were produced and heat-treated to attain fine grain and coarse grain microstructures that represent the conventionally processed and grain boundary engineered (GBE) conditions, respectively. For each of the four microstructural variants of RR1000, the twin density and grain size were characterized and were in agreement with the desired microstructural attributes. In order to validate the deformation mechanisms and fatigue behavior of the material, high-resolution digital image correlation was performed to generate strain maps relative to the microstructural features. The high density of twin boundaries was confirmed to inhibit the length of slip bands, which is directly attributed to extended fatigue life. Thus, this study demonstrated the successful role of models, both process and performance, in the design and manufacture of Ni-based superalloy disk forgings.

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Microstructural and processing factors influencing the formation of annealing twins

Cited by 65 publications

References 25 publications

Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

Σ3 CSL boundary distributions in an austenitic stainless steel subjected to multidirectional forging followed by annealing

Tailoring the Properties of a Ni-Based Superalloy via Modification of the Forging Process: an ICME Approach to Fatigue Performance

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