Grain Boundary Engineering of Strain-Annealed Hastelloy-X

2021 ◽  
Vol 1016 ◽  
pp. 852-856
Author(s):  
Waqas Muhammad ◽  
Daniel Wei ◽  
Étienne Martin
Keyword(s):  
Grain Boundary ◽  
Boundary Migration ◽  
Applied Strain ◽  
Annihilation Rate ◽  
Grain Boundary Engineering ◽  
Hastelloy X ◽  
Dissociation Mechanism ◽  
Annealing Conditions ◽  
High Annealing ◽  
Annealing Twins

The present study investigates the occurrence and effectiveness of the dissociation mechanism of Σ3 CSL boundaries into its variants such as Σ9 and Σ27a-b during strain-annealed grain boundary engineering (GBE) of Hastelloy-X. Multiple cold-rolling strain levels and annealing conditions are studied and it is observed that the density of ∑3 boundaries decreases proportionally to the amount of strain induced boundary migration (SIBM) during the GBE process. The dissociation mechanism of Σ3 annealing twins is activated at the onset of SIBM, causing an increase in the density of the Σ3n variants. It is shown that at high annealing times or temperatures, the rate of generation of CSL boundaries through dissociation mechanism is lower than their annihilation rate. It is further suggested that the dissociation mechanism of ∑3 boundaries during GB migration is more efficient when the amount of applied strain prior to annealing is kept low, thus promoting disruption of the random GB network.

scholarly journals Formation of Annealing Twins during Recrystallization and Grain Growth in 304L Austenitic Stainless Steel

2013 ◽  
Vol 753 ◽  
pp. 113-116 ◽  
Author(s):  
Yuan Jin ◽  
M. Bernacki ◽  
G.S. Rohrer ◽  
Anthony D. Rollett ◽  
B. Lin ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Migration ◽  
Annealing Twin ◽  
Strain Level ◽  
Grain Boundary Engineering ◽  
Twin Density ◽  
Annealing Twins

Understanding of the mechanisms of annealing twin formation is fundamental for grain boundary engineering. In this work, the formation of annealing twins in a 304L austenitic stainless steel is examined in relation to the thermo-mechanical history. The behaviour of annealing twins of various morphologies is analysed using an in-situ annealing device and EBSD. The results confirm that there is a synergistic effect of prior strain level on annealing twin density generated during recrystallization. The higher the prior strain level, the higher the velocity of grain boundary migration and the higher the annealing twin density in the recrystallized grains. This effect decreases as the recrystallization fraction increases. The existing mathematical models (Pande's model and Gleiter's model), which were established to predict annealing twin density in the grain growth regime, can not predict this phenomenon.

Grain Growth Control in Grain Boundary Engineered Microstructures

2012 ◽  
Vol 715-716 ◽  
pp. 103-108 ◽  
Author(s):  
Valerie Randle ◽  
Mark Coleman
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Stainless Steels ◽  
Growth Control ◽  
Austenitic Stainless Steels ◽  
Grain Boundary Engineering ◽  
Size Measurement ◽  
Annealing Twins ◽  
And Control ◽  
Measurement And Control

Grain boundary engineering (GBE) to promote degradation-resistant interfaces in the microstructure usually requires that the grain size remains small so that strength is not compromised. Aspects of grain size measurement and control will be reviewed and discussed for a variety of GBE materials such as copper, nickel, nickel-based alloys and austenitic stainless steels, particularly in the light of the high proportion of annealing twins that constitute the GBE microstructure.

Micromechanisms Involved in Grain Boundary Engineering

2005 ◽  
Vol 495-497 ◽  
pp. 1225-1230
Author(s):  
Andre Luiz Pinto ◽  
Carlos Sergio da Costa Viana ◽  
Luiz Henrique de Almeida
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Coincidence Site Lattice ◽  
Inconel 625 ◽  
Grain Boundary Engineering ◽  
Inconel 600 ◽  
Special Boundaries ◽  
Deformation Step ◽  
Backscatter Diffraction

Grain boundary engineering has been applied to different materials in order to increase properties particularly sensitive to intergranular phenomena. This work analyses the micromechanisms that allow the control of the amount of special boundaries which respect coincidence site lattice theory. α-brass, a lead alloy, Inconel 625 and Inconel 600 were submitted to different thermomechanical treatments and were analyzed via electron backscatter diffraction in order to characterize their grain boundaries. The occurrence of thin twins in some crystal directions during the deformation step seems to determine the results obtained as well as strain induced boundary migration.

“Strain-annealed” grain boundary engineering process investigated in Hastelloy-X

Materialia ◽  
2020 ◽  
Vol 9 ◽  
pp. 100544
Author(s):  
Étienne Martin ◽  
Waqas Muhammad ◽  
Andrew J. Detor ◽  
Ian Spinelli ◽  
Andrew Wessman ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundary Engineering ◽  
Engineering Process ◽  
Hastelloy X

Control of precipitation behaviour of Hastelloy-X through grain boundary engineering

2017 ◽  
Vol 33 (17) ◽  
pp. 2078-2085 ◽  
Author(s):  
Xiaoyan Wang ◽  
Kentaro Kurosawa ◽  
Ming Huang ◽  
Xianke Lu ◽  
Dao Zhang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundary Engineering ◽  
Hastelloy X ◽  
Precipitation Behaviour

Fourier Spectral Phase Field Simulations of Elastically Anisotropic Heterogeneous Polycrystals

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
J. B. Allen
Keyword(s):  
Grain Boundary ◽  
Phase Field ◽  
Grain Orientation ◽  
Boundary Migration ◽  
Phase Field Model ◽  
Free Energy Density ◽  
Applied Strain ◽  
Stress Distributions ◽  
Triple Junctions ◽  
Boundary Triple

Abstract In this study, we developed a multi-order, phase field model to compute the stress distributions in anisotropically elastic, inhomogeneous polycrystals and study stress-driven grain boundary migration. In particular, we included elastic contributions to the total free energy density and solved the multicomponent, nonconserved Allen–Cahn equations via the semi-implicit Fourier spectral method. Our analysis included specific cases related to bicrystalline planar and curved systems as well as polycrystalline systems with grain orientation and applied strain conditions. The evolution of the grain boundary confirmed the strong dependencies between grain orientation and applied strain conditions and the localized stresses were found to be maximum within grain boundary triple junctions.

Origin and Role of Σ3 Boundaries during Thermo-Mechanical Processing of a Ti-Modified Austenitic Stainless Steel

2011 ◽  
Vol 702-703 ◽  
pp. 714-717 ◽  
Author(s):  
Sumantra Mandal ◽  
A.K. Bhaduri ◽  
V. Subramanya Sarma
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Hot Deformation ◽  
Cold Deformation ◽  
Grain Boundary Engineering ◽  
Annealing Twins ◽  
High Fraction ◽  
Deformation Tests

The origin and role of S3 boundaries during dynamic recrystallization (DRX) and grain boundary engineering (GBE) of a Ti-modified austenitic stainless steel (alloy D9) is studied. Hot deformation tests were carried out on solution-annealed (SA) specimens to study the DRX behavior whereas a series of cold deformation and annealing were performed on SA specimens to realize GBE microstructure. A linear relationship between the area fraction of DRX and the number fraction of Σ3 boundaries was observed during hot deformation. This high fraction of Σ3 boundaries could account for the formation of coherent annealing twins by “growth accidents” during DRX. For certain combinations of cold deformation and annealing, a significant increase in S3 boundaries was observed. In contrast to hot deformation, majority of these new S3 boundaries during cold deformation and annealing were formed by geometrical interactions between the pre-existing Σ3 boundaries. The role of the S3 boundaries during DRX and on tailoring microstructure through grain boundary engineering approach is discussed.

Mechanisms of Dynamic Recrystallization in Coarse Columnar-Grained Cu-Sn-P Alloy

2012 ◽  
Vol 715-716 ◽  
pp. 586-592
Author(s):  
Hiromi Miura ◽  
Masato Watanabe ◽  
Takashi Shirai ◽  
Akihiko Ishibashi
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Boundary Migration ◽  
True Strain ◽  
Compression Tests ◽  
Model Sample ◽  
Annealing Twins ◽  
Preferential Nucleation ◽  
Increasing Temperature

Dynamic recrystallization (DRX) behavior in a coarse columnar-grained Cu-0.65Sn-0.025P and Cu-0.025P (mass%) alloys were systematically investigated by compression tests at temperatures between 1073 K and 1253 K and at true strain rates from 2 x 10-4s-1to 2 x 10-1s-1in vacuum. As a model sample, an orientation-controlled bicrystal having [0 1 twist 18oboundary was prepared and also hot deformed. Appearance of the peaks stress, where DRX onsets, was much delayed in Cu-Sn-P alloy compared with that in Cu-0.025P alloy. The onset of DRX was, therefore, obviously impeded by the small addition of Sn to Cu-P. While nucleation of new grains took place almost at random in Cu-Sn-P when strain rate was high enough, it tended to appear more preferentially at grain boundary with decreasing strain rate and with increasing temperature. The most of new grains were annealing twins formed behind the migrating grain boundary. Because grain boundary migration took place more extensively with increasing temperature and with decreasing strain rate, the preferential nucleation at grain boundary became more significant.

Evolution of Grain Boundary Character Distribution in Pure Copper during Low-Strain Thermomechanical Processing

2019 ◽  
Vol 944 ◽  
pp. 229-236
Author(s):  
Guo Qing Wu ◽  
Zi Yun Chen ◽  
Ming Huang ◽  
Yuan Qin ◽  
Alimjan Ablat ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Thermomechanical Processing ◽  
Boundary Migration ◽  
Pure Copper ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution

In order to get optimal grain boundary character distribution (GBCD) and grain boundary properties, thermomechanical processing (TMP) is usually adopted in grain boundary engineering. However, the mechanism behind the TMP treatments and GBCD optimization is still unclear. The present study has conducted a series experiments involving low-strain TMPs to study the relationship between TMP parameters and the behind microstructural evolution. The experimental results indicate that in the scope of low-strain TMP, strain induced boundary migration (SIBM) is the most effective process for GBCD optimization. Besides, SIBM and grain growth would gradually transfer to recrystallization with the increase of pre-deformation level and annealing temperature. Further quasi in-situ EBSD results infer that SBIM is activated locally in some region with high stored energy, and further gradual initiation of SIBM from one region to another contributes to the gradual increase of special boundaries with annealing time.

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