Altering Corrosion Response via Grain Boundary Engineering

2008 ◽  
Vol 595-598 ◽  
pp. 409-418 ◽  
Author(s):  
L. Tan ◽  
Kumar Sridharan ◽  
T.R. Allen
Keyword(s):  
Grain Boundary ◽  
Power Systems ◽  
Nuclear Power ◽  
Electron Backscatter Diffraction ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Grain Boundary Character ◽  
Potential Applications ◽  
Inconel 617 ◽  
Distribution Studies

Grain boundary engineering (GBE) was employed to improve the oxide exfoliation resistance and mitigate oxide growth by optimizing the grain boundary character distribution. Studies were performed on alloys of Incoloy 800H and Inconel 617. Alloys 800H and 617 were selected due to their potential applications for the Generation IV nuclear power systems. The effect of GBE on the corrosion response was evaluated using supercritical water exposure tests and cyclic oxidation tests. The microstructure of the tested samples was analyzed by means of optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction, and gravimetry. The effects of thermal expansion mismatch and Cr volatilization on the corrosion response are discussed.

Grain Boundary Engineering: Progress and Challenges

2007 ◽  
Vol 539-543 ◽  
pp. 3389-3394 ◽  
Author(s):  
Wei Guo Wang
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Electron Backscatter Diffraction ◽  
Coincidence Site Lattice ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Special Boundaries ◽  
Grain Boundary Character ◽  
Proposed Model ◽  
Backscatter Diffraction

The progress of grain boundary engineering (GBE) is overviewed and the challenges for further investigations emphasized. It points out that, the electron backscatter diffraction (EBSD) reconstruction of grain boundaries, which gives the information of connectivity interruption of general high angle boundaries (HABs), is more significant than purely pursuing high frequency of so-called special boundaries. The criterion for the optimization of grain boundary character distribution (GBCD) needs to be established. The energy spectrum and the degradation susceptibility of grain boundaries of various characters including HABs and low Σ（Σ≤29） coincidence site lattice (CSL) needs to be studied and ascertained. And finally, the newly proposed model of non-coherent Σ3 interactions for GBCD optimization are discussed.

Grain Boundary Investigation of AISI 304 Type Steel Using EBSD

2010 ◽  
Vol 659 ◽  
pp. 307-311
Author(s):  
Zoltán Gaál ◽  
Péter János Szabó ◽  
János Ginsztler ◽  
László Dévényi
Keyword(s):  
Grain Boundary ◽  
Evaluation Method ◽  
Boundary Structure ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Aisi 304 ◽  
Grain Boundary Character ◽  
Treatment Processes ◽  
Grain Boundary Structure ◽  
Electron Back Scattered Diffraction

This paper deals with the investigation of grain boundary engineering processes in case of AISI 304 type austenitic stainless steel. The effects of the thermo-mechanical treatments for the modification of the grain boundary structure are demonstrated on the special grain boundaries. The proper thermo-mechanical treatments can increase the fraction of the CSL-boundaries. Since the CSL-boundaries are resistant against intergranular degradation processes, materials owning enhanced properties can be developed due to these treatments. The investigation of the grain boundary character distribution is carried out by automated electron back scattered diffraction (EBSD) measurements after different thermo-mechanical treatment processes. The effect of the heat treatment duration on the grain boundary structure is examined; the optimal treatment is represented. It is shown by experimental results, that the parameter settings of the evaluation method strongly influence the obtained results.

scholarly journals Recent Advances in EBSD Characterization of Metals

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1097
Author(s):  
Íris Carneiro ◽  
Sónia Simões
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Microstructural Characterization ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Character ◽  
Recent Advances ◽  
Wide Range ◽  
Plane Distribution ◽  
Backscatter Diffraction

Electron backscatter diffraction (EBSD) has been attracting enormous interest in the microstructural characterization of metals in recent years. This characterization technique has several advantages over conventional ones, since it allows obtaining a wide range of characterization possibilities in a single method, which is not possible in others. The grain size, crystallographic orientation, texture, and grain boundary character distribution can be obtained by EBSD analysis. Despite the limited resolution of this technique (20–50 nm), EBSD is powerful, even for nanostructured materials. Through this technique, the microstructure can be characterized at different scales and levels with a high number of microstructural characteristics. It is known that the mechanical properties are strongly related to several microstructural aspects such as the size, shape, and distribution of grains, the presence of texture, grain boundaries character, and also the grain boundary plane distribution. In this context, this work aims to describe and discuss the possibilities of microstructural characterization, recent advances, the challenges in sample preparation, and the application of the EBSD in the characterization of metals.

Grain Boundary Engineering for the Control of Mechanical Properties and Oxidation-Induced Embrittlement in Silicon Carbides

2004 ◽  
Vol 261-263 ◽  
pp. 999-1004 ◽  
Author(s):  
Sadahiro Tsurekawa ◽  
Tadao Watanabe ◽  
N. Tamari
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Boundary ◽  
Ceramic Materials ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Special Boundaries ◽  
Grain Boundary Character ◽  
And Performance ◽  
Boundary Microstructure

Grain boundary engineering (GBE) is rapidly emerging recently as a powerful tool for achieving enhanced properties and performance in polycrystalline metallic materials. The objective of this work is to confirm the potential of GBE for enhancement in properties and performance in ceramic materials such as silicon carbide (SiC). Grain boundary microstructure in SiC could be tailored by doping with different elements (Mg, Al and P) and modifying sintering processing (hot-pressing and spark plasma sintering). FEG-SEM/OIM analyses revealed that both Al doping and SPS increased the frequency of low-energy special boundaries (Σ ≤29 ) and Mg doping enhanced grain growth. It was found that mechanical properties like microhardness depended on the grain boundary character distribution (GBCD) and the grain size. The increment in the frequency of special boundaries could yield increases in the Vickers-microhardness and the fracture stress. Furthermore, intergranular oxidation-induced brittleness in SiC was noticeably improved by increase in the frequency of special boundaries and decrease in the grain size. Thus, we have confirmed that the control of grain boundary microstructure such as grain size, GBCD and grain boundary connectivity is a key for enhancement in bulk properties and performance in ceramic materials.

The Relationship between Grain Boundary Character Distribution and Intergranular Corrosion Resistance of 304 Austenitic Stainless Steel

2011 ◽  
Vol 689 ◽  
pp. 239-244
Author(s):  
Xiao Ying Fang ◽  
Xiao Cui ◽  
Cong Xiang Qin ◽  
Wei Guo Wang
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Intergranular Corrosion ◽  
Electron Backscatter Diffraction ◽  
Grain Boundary Character Distribution ◽  
Surface Appearance ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
304 Austenitic Stainless Steel

A wedge-shaped 304 austenitic stainless steel with varied thickness longitudinally was cold rolled into a flat one and then annealed at 1323K for 10 min. The grain boundary character distributions (GBCDs) in the specimen as processed were examined by the means of Electron backscatter diffraction (EBSD). The results showed that, at the regions with low pre-strains ranged from 4% to 6%, quite high fractions of S3n (n=0,1,2,3) grain boundaries and large-sized S3n (n=0,1,2,3) grain clusters are introduced compared with the regions of quite low ( less than 2.5%) or relatively high pre-strain. The surface appearance of after corrosion test reveals that grain dropping due to intergranular corrosion (IGC) is depressed and the penetration of IGC from the surface into the interior in the cross-section is arrested significantly as well in the regions with high fractions of S3n boundaries and large-sized S3n grain clusters.

Prediction and Control of Grain Boundary Fracture in Brittle Materials on the Basis of the Strongest-Link Theory

2005 ◽  
Vol 482 ◽  
pp. 55-62 ◽  
Author(s):  
Tadao Watanabe ◽  
Sadahiro Tsurekawa
Keyword(s):  
Grain Boundary ◽  
Intergranular Fracture ◽  
Boundary Energy ◽  
Boundary Structure ◽  
Polycrystalline Materials ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Engineering ◽  
Grain Boundary Character ◽  
Grain Boundary Structure ◽  
Link Theory

This paper discusses micropstructural aspects of brittleness fracture of polycrystalline materials caused by intergranular fracture. Structure-dependent intergranular brittle fracture in bicrystals and polycrystals are discussed and predicted theoretically. Experimental evidence for the structure-dependent intergranular fracture is shown and some general features are discussed to demonstrate the relationship between grain boundary structure/character, grain boundary energy and intergranular fracture strength. Theoretical prediction of the fracture toughness based on the strongest-link theory is introduced for polycrystals with different grain boundary microstructures, primarily defined by the grain boundary character distribution, grain boundary connectivity. Finally recent achievements of successful control of intergranular brittleness by grain boundary engineering based on the strongest-link theory are introduced for different materials.

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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