Computer Simulation of Grain Boundary Character in a Superplastic Aluminum Alloy

1999 ◽  
Vol 601 ◽  
Author(s):  
T.R. McNelley ◽  
M.T. Peréz-Prado
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Polycrystalline Materials ◽  
High Angle ◽  
Boundary Character ◽  
Computer Methods ◽  
Fine Grain ◽  
Grain Boundary Character ◽  
Deformation Banding ◽  
Processed Material

AbstractHigh-angle grain boundaries are generally deemed necessary for superplasticity in metals. In polycrystalline materials the grain boundary character must be described in terms of a probability distribution rather than by a single parameter, and little has been reported on the relationship between this distribution and fine-grain superplasticity. For aluminum alloys that exhibit continuous recrystallization the results of computer-aided electron backscatter diffraction analysis have shown that bimodal grain boundary disorientation distributions are present in as-processed material and persist during subsequent annealing. Such distributions may be simulated by computer methods based on a model of the microstructure which assumes that deformation banding occurs during deformation processing. High-angle boundaries (≥30°) develop in association with deformation banding while boundaries of lower disorientation (<30°) develop by dislocation reaction within the bands. Improved understanding of the grain boundary types associated with various microstructural transformation mechanisms will aid the design of processes to produce superplastic microstructures.

scholarly journals Influence of Grain Boundary Character and Annealing Time on Segregation in Commercially Pure Nickel

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Shery L. Welsh ◽  
Monica Kapoor ◽  
Olivia D. Underwood ◽  
Richard L. Martens ◽  
Gregory B. Thompson ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Annealing Time ◽  
Electron Backscatter Diffraction ◽  
Atom Probe ◽  
Pure Nickel ◽  
Polycrystalline Materials ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Commercially Pure

Commercially pure nickel (Ni) was thermomechanically processed to promote an increase in Σ3 special grain boundaries. Engineering the character and chemistry of Σ3 grain boundaries in polycrystalline materials can help in improving physical, chemical, and mechanical properties leading to improved performance. Type-specific grain boundaries (special and random) were characterized using electron backscatter diffraction and the segregation behavior of elements such as Si, Al, C, O, P, Cr, Mg, Mn, B, and Fe, at the atomic level, was studied as a function of grain boundary character using atom probe tomography. These results showed that the random grain boundaries were enriched with impurities to include metal oxides, while Σ3 special grain boundaries showed little to no impurities at the grain boundaries. In addition, the influence of annealing time on the concentration of segregants on random grain boundaries was analyzed and showed clear evidence of increased concentration of segregants as annealing time was increased.

SEM-ECP Analysis of Grain-Boundary Character Distribution in Polycrystalline Materials

1996 ◽  
Vol 54 ◽  
pp. 354-355
Author(s):  
Tadao Watanabe
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Polycrystalline Materials ◽  
Grain Boundary Character Distribution ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution

As demonstrated early 1980’s (1), the scanning electron rnicrocopy-electron channelling pattern (SEM-ECP) technique is very powerful in determination of orientation of individual grains and the character of grain boundaries in polycrystalline materials. Figure 1(a) and (b) show SEM and ECP images of a grain boundary in polycrystal line iron-6.5 mass % silicon ribbon produced by rapid solidification and subsequent annealing. We can intuitively recognize from the SEM-ECP image that the character of the boundary is of <100> tilt type with about 7° misorientation angle. This kind of direct observation is very useful for a study of grain boundary migration and grain growth.This paper discusses advantages of the SEM-ECP technique for the precise determination of the character of grain boundary and for statistical analysis of grain boundaries to bridge roles of individual grain boundaries and bulk properties in a polycrystal. The new microstructural parameter associated with grin boundary termed “grain boundary character distribution (GBCD)” which was introduced by the present author (2,3) and has been utilized in designing and engineering grain boundaries in order to produce desirable and/or high bulk performance in polycrystalline materials (4,5). GBCD describes the type and the frequency of different types of grain boundaries, ie. random general boundaries and special boundaries like low-angle boundaries and low Σ coincidence boundaries.

Microtexture Study of Warm-Rolled High Strength Interstitial-Free (IF) Steel Sheets

2011 ◽  
Vol 682 ◽  
pp. 71-74
Author(s):  
Cai Nian Jing ◽  
Ming Gang Wang ◽  
Xi Jun Liu ◽  
Qi Zhong Tan ◽  
Zuo Cheng Wang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
High Strength ◽  
Interstitial Free ◽  
If Steel ◽  
Boundary Character ◽  
Deep Drawability ◽  
Grain Boundary Character ◽  
High Strength If Steel

Interstitial-free (IF) steel has excellent deep-drawability and was used widely in automotive industry. High strength IF-steel is that some phosphorus was put in common IF-steel to improve its strength without destroying the deep-drawability [1]. Microstructure and grain boundary character strongly affect the deep-drawability of high strength IF-steel, it is an obligatory task to test those characters. The technique of Electron Backscatter Diffraction (EBSD) can reveal the microtexture and detailed orientation distribution of grains from a single EBSD map, as a powerful instrument, EBSD was used widely in materials research from last decade [2]. Many researches have been focused on the texture evolution and recrystallization phenomena of high strength IF-steels [3,4], but the microtexture and grain boundary characters of warm-rolled high strength IF-steels was not fully investigated. The present study was aimed at researching the microtexture characters of a commercial high strength IF-steels under different warm-rolled temperature using EBSD technique, the microstructure and grain boundary character were analyzed systemically, and the relationship between the microstructure and deep-drawability was discussed.

Grain Boundary Character of 9Cr Feritic/Martensitic Heat Resistant Steels Strengthened by Nano-Sized MX Precipitates

2010 ◽  
Vol 638-642 ◽  
pp. 2882-2887
Author(s):  
Feng Shi Yin
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Stress Rupture ◽  
Low Carbon ◽  
Boundary Character ◽  
Carbon And Nitrogen ◽  
Heat Resistant ◽  
Grain Boundary Character ◽  
Nitrogen Contents ◽  
Heat Resistant Steels

In this work, two heats of 9Cr ferritic/martensitic heat resistant steels with different carbon and nitrogen contents were prepared. The steels were designed to have much lower carbon content than conventional 9-12Cr heat resistant steels for obtaining dense nano-sized MX precipitates. Microstructure of the two steels in different heat treatment states was analyzed by electron backscatter diffraction (EBSD) method. The results show that grain boundary character is greatly affected by carbon and nitrogen contents. Martensite in the steel with 0.02wt.% carbon and ultra low nitrogen is easier to recrystallize than that in the steel with ultra low carbon and 0.03wt.% nitrogen during tempering treatment. The effect of grain boundary character on stress rupture properties is also discussed.

Dislocation density based crystal plasticity finite element simulation of Al bicrystal with grain boundary effects

2014 ◽  
Vol 1651 ◽  
Author(s):  
Zhe Leng ◽  
David P. Field ◽  
Alankar Alankar
Keyword(s):  
Finite Element ◽  
Dislocation Density ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Crystal Plasticity ◽  
Microstructure Evolution ◽  
Polycrystalline Materials ◽  
Boundary Character ◽  
Crystal Plasticity Finite Element ◽  
Grain Boundary Character

ABSTRACTCrystal plasticity finite element method is a useful tool to investigate the anisotropic mechanical behaviors as well as the microstructure evolution of metallic materials and it is widely used on single crystals and polycrystalline materials. However, grain boundary involved mechanisms are barely included in the polycrystalline models, and modeling the interaction between the dislocation and the grain boundaries in polycrystalline materials in a physically consisstent way is still a long-standing, unsolved problem. In our analysis, a dislocation density based crystal plasticity finite element model is proposed, and the interaction between the dislocation density and the grain boundaries is included in the model kinematically. The model is then applied to Al bicrystals under 10% compression to investigate the effects of grain boundary character, e.g. grain boundary misorientation and grain boundary normal, on the stress state and the microstructure evolution. The modeling results suggest a reasonable correspondence with the experimental result and the grain boundary character plays a crucial role in the stress concentration and dislocation patterning.

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.

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