Investigation of the relationship between intergranular corrosion and retrogression and reaging in the AA6063

2019 ◽  
Vol 70 (12) ◽  
pp. 2256-2265
Author(s):  
Gökhan Özer ◽  
Alptekin Kisasöz ◽  
Ahmet Karaaslan
Keyword(s):  
Intergranular Corrosion ◽  
Retrogression And Reaging ◽  
The Relationship

On the Relationship Between Grain-Boundary Character Distribution and Intergranular Corrosion

1996 ◽  
Vol 54 ◽  
pp. 346-347
Author(s):  
E.M. Lehockey ◽  
G. Palumbo ◽  
P. Lin ◽  
A. Brennenstuhl
Keyword(s):  
Grain Boundaries ◽  
Intergranular Corrosion ◽  
Grain Boundary Character Distribution ◽  
Hexagonal Prism ◽  
Material Loss ◽  
Creep Properties ◽  
Special Boundaries ◽  
Grain Boundary Character ◽  
The Matrix ◽  
The Relationship

Intergranular corrosion can under severe conditions lead to “grain-dropping” which results in significant material loss. It has been demonstrated that grain boundaries described by low-Σ CSL misorientations are more resistant to corrosion, cracking (SCC), and sliding (creep) than “general” boundaries, and that the frequency of these “special” boundaries can be enhanced offering the possibility of producing materials with improved bulk corrosion and creep properties. This contribution presents a model for predicting the effect of “special” boundaries on the extent of gross wastage from grain-dropping.For any grain to be ejected from the matrix, all of its bounding interfaces must be fully compromised. Assuming “special” grain boundaries are immune to corrosion and considering a material containing hexagonal prism grains with a diameter and length, d, it can be shown that the probability, X, of observing grain-dropping at a depth, L, through the material thickness is related to the “special” boundary fraction, Fsp, by:

Change of Intergranular Corrosion Behavior along the Thickness in a Friction-Stir-Welded 7N01-T5 Aluminum Alloy

2018 ◽  
Vol 941 ◽  
pp. 1754-1759
Author(s):  
Zhi Qiang Zhang ◽  
Ying Li ◽  
Yan Shuang Xing ◽  
Hua Yin ◽  
Chang Shu He
Keyword(s):  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
Intergranular Corrosion ◽  
Corrosion Property ◽  
Temperature Cycling ◽  
Bottom Surface ◽  
Direction Parallel ◽  
Friction Stir ◽  
Welding Direction ◽  
The Relationship

The intergranular corrosion behavior of friction-stir-welded 7N01-T5 aluminum alloy joints was investigated by using sliced samples extract from the top, middle and bottom layers of the joint, with the sliced direction parallel to the welding direction. The relationship between microstructure and local corrosion property of the welded joints was analyzed. The results show that the heat-affected zone (HAZ) of the weld exhibit the highest susceptibility to intergranular corrosion, and the corrosion degree of the top and bottom surface layers were more serious than the central layer in the HAZ, continuously dispersed precipitates on grain boundaries and the grains size may be the main factor which caused the different corrosion severity of HAZ. The thermo-mechanically affected zone (TMAZ) is characterized by a highly deformed structure, and the temperature reached in this local zone during welding is high enough for the strengthening precipitates, especially the precipitates on the grain boundary to be partially re-dissolved. The temperature gradient caused resistance to intergranular corrosion of TMAZ reduced from top to bottom surface. The stirred zone (SZ) experienced heavily plastic deformation and temperature cycling, the sensibility of intergranular corrosion was low, which is attributed to the sufficient re-dissolve of the strengthening precipitates during welding.

The Effect of S Segregation on the Grain Boundary Geometry of a Σ11 Nickel Bicrystal

1991 ◽  
Vol 229 ◽  
Author(s):  
Mary C. Juhas ◽  
Louisette Priester
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Intergranular Fracture ◽  
Intergranular Corrosion ◽  
Temper Embrittlement ◽  
Solute Segregation ◽  
Premature Failure ◽  
Boundary Geometry ◽  
Engineering Materials ◽  
The Relationship

Grain boundary (GB) solute segregation has long been associated with premature failure of engineering materials. Local changes in composition at the GBs can result in such phenomena as intergranular corrosion, temper embrittlement, intergranular fracture and fatigue as well as changes in electrical properties. The relationship between GB structure and solute segregation is not well understood.

scholarly journals Crystallographic Evaluation of Susceptibility to Intergranular Corrosion in Austenitic Stainless Steel with Various Degrees of Sensitization

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 613 ◽  
Author(s):  
Tomoyuki Fujii ◽  
Takaya Furumoto ◽  
Keiichiro Tohgo ◽  
Yoshinobu Shimamura
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Intergranular Corrosion ◽  
Coincidence Site Lattice ◽  
Unit Cell ◽  
304 Stainless Steel ◽  
Cell Area ◽  
Sigmoid Curve ◽  
The Stability ◽  
The Relationship

This study investigated the susceptibility to intergranular corrosion (IGC) in austenitic stainless steel with various degrees of sensitization (DOSs) from a microstructural viewpoint based on the coincidence site lattice (CSL) model. IGC testing was conducted using oxalic acid and type 304 stainless steel specimens with electrochemical potentiokinetic reactivation (EPR) ratios that varied from 3 to 30%. As a measure of IGC susceptibility, the width of the corroded groove was used. The relationship between IGC susceptibility, grain boundaries (GB) structure, and EPR ratio of the specimens was evaluated. As a result, the IGC susceptibility cannot be characterized using the Σ value, irrespective of the DOS of the specimen. The IGC susceptibility increases with increasing unit cell area of CSL boundaries, which is a measure of the stability of the CSL boundaries, and then levels off. The relationship between the IGC susceptibility and unit cell area is sigmoidal, irrespective of the DOS of the specimen. The sigmoid curve shifts rightward and the upper bound of IGC susceptibility decreases with decreasing DOS of the specimen.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

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