Effect of Equal-Channel Angular Pressing on the Pitting Corrosion Resistance of Al Alloy

2006 ◽  
pp. 487-492
Author(s):  
In-Joon Son ◽  
Hiroaki Nakano ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Al Alloy ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance

Effect of Equal-Channel Angular Pressing on the Pitting Corrosion Resistance of Al Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 487-492 ◽  
Author(s):  
In-Joon Son ◽  
Hiroaki Nakano ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Formation Rate ◽  
Electrochemical Techniques ◽  
Mg Alloy ◽  
Al Alloy ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pitting Corrosion Resistance

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of Al and Al-Mg alloy was investigated by means of polarization curves in solutions containing 300 ppm of Cl- and by surface analysis. The potentials for pitting corrosion of Al and Al-Mg alloy were evidently shifted to the noble direction by using the ECAP process, indicating that this process improves resistance to pitting corrosion. This increase in resistance seems to be attributable to the increase in formation rate of Al oxide films due to the increase in grain boundary with ECAP. The pitting corrosion resistance of Al and Al-Mg alloy anodized galvanostatically in H2SO4 solution after ECAP was also investigated using electrochemical techniques. The pitting corrosion resistance of Al and Al-Mg alloy was remarkably improved by anodizing. However, the pitting corrosion resistance of anodized Al-Mg alloy was better without ECAP than with ECAP.

Effect of severe plastic deformation by ECAP on corrosion behaviour of aluminium alloy AA 7075

2016 ◽  
Vol 81 (2) ◽  
pp. 55-61 ◽  
Author(s):  
M. Ilieva ◽  
R. Radev
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Corrosion Behaviour ◽  
Chloride Concentration ◽  
Chloride Ions ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance ◽  
Aa 7075

Purpose: The present study compares the corrosion behaviour of overaged AA 7075 before and after equal channel angular pressing ECAP in two media, containing chlorides, in order to answer the question how grain refinement of aluminium alloys influences their corrosion properties.Design/methodology/approach: The effect of equal channel angular pressing ECAP on corrosion behaviour of aluminium alloy AA 7075 was studied in two water solutions, containing chloride ions: 1) 0.01 M Na2SO4 with addition of 0.01%Cl-, and 2) 3g/l H2O2 and 57g/l NaCl. The changes in electrochemical characteristics, provoked by grain size refinement after equal channel angular pressing ECAP, were found using potentiodynamic polarisation. Steady state potential, corrosion potential, corrosion current density; breakdown (pitting) potential of overaged and deformed by equal channel angular pressing ECAP aluminium alloy AA 7075 were measured.Findings: In the environment with lower chloride concentration equal channel angular pressing ECAP process led to increase in pitting corrosion resistance and in the medium with higher chloride concentration - to decrease in pitting corrosion resistance. That way grain refinement does not demonstrate a uni-directional influence on corrosion resistance of AA 70775.Research limitations/implications: The results suggest the possibility for development of materials having the same chemical composition but with different corrosion resistance to different environments.Originality/value: The paper presents the corrosion behaviour of ultrafine-grained aluminium alloy AA 7075 and the influence of the chloride ions concentration in the corrosion medium on this behaviour.

scholarly journals Effect of Equal Channel Angular Pressing on the Pitting Corrosion Resistance of Aluminum-Copper Alloy

2010 ◽  
Vol 61 (1) ◽  
pp. 50-57
Author(s):  
In-Joon SON ◽  
Hiroaki NAKANO ◽  
Satoshi OUE ◽  
Shigeo KOBAYASHI ◽  
Hisaaki FUKUSHIMA ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Copper Alloy ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance ◽  
Aluminum Copper Alloy

Effect of equal-channel angular pressing on pitting corrosion resistance of anodized aluminum-copper alloy

2009 ◽  
Vol 19 (4) ◽  
pp. 904-908 ◽  
Author(s):  
In-Joon SON ◽  
Hiroaki NAKANO ◽  
Satoshi OUE ◽  
Shigeo KOBAYASHI ◽  
Hisaaki FUKUSHIMA ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Copper Alloy ◽  
Anodized Aluminum ◽  
Angular Pressing ◽  
Pitting Corrosion Resistance ◽  
Aluminum Copper Alloy

Effect of Equal Channel Angular Pressing on the Pitting Corrosion Resistance on the Aluminum Alloys with/without Anodization

2010 ◽  
Vol 638-642 ◽  
pp. 1989-1994 ◽  
Author(s):  
Hiroaki Nakano ◽  
In Joon Son ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Formation Rate ◽  
Oxide Films ◽  
Mg Alloy ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pitting Corrosion Resistance ◽  
Al Oxide

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of Al (AA1100) and Al-Mg (AA5052) alloy with anodization and without was investigated by means of polarization curves in solutions containing 300 ppm or 0.6 mol/L of Cl- and by surface analysis. In Al and Al-Mg alloy without anodization, the potentials for pitting corrosion were evidently shifted to the noble direction by ECAP process, indicating that this process improves resistance to pitting corrosion. SEM observation revealed that the pitting corrosion occurred near the impurity precipitates and the size of impurity precipitated decreased with ECAP process. The time-dependence of corrosion potential and the polarization resistance determined by AC impedance technique suggested that the formation rate of Al oxide films was increased with ECAP process. The improvement in pitting corrosion resistance of Al and Al-Mg by ECAP seems to be attributable to the decrease in the size of impurity precipitates and the increase in the formation rate of Al oxide films. On the other hand, the time required for initiating pitting corrosion of anodised Al was longer with ECAP than without, indicating improvement in the pitting corrosion resistance by application of ECAP. However, the pitting corrosion of anodized Al-Mg alloy occurred earlier with ECAP than without, showing that the corrosion resistance was worse with ECAP than without. In anodized Al-Mg alloy, cracks occurred in the anodic oxide films during initial corrosion and the cracks were larger with ECAP than without. It is assumed that the pitting corrosion was promoted by the cracks due to the higher internal stress resulting from ECAP.

scholarly journals Effect of Equal-Channel Angular Pressing on Pitting Corrosion of Pure Aluminum

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Injoon Son ◽  
Hiroaki Nakano ◽  
Satoshi Oue ◽  
Shigeo Kobayashi ◽  
Hisaaki Fukushima ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
Pure Aluminum ◽  
Electrochemical Techniques ◽  
Oxide Films ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pitting Corrosion Resistance ◽  
Al Oxide

The effect of equal-channel angular pressing (ECAP) on the pitting corrosion of pure Al was investigated using electrochemical techniques in solutions containing 0.1 m mol·dm−3of Na2SO4and 8.46 mol·dm−3of NaCl (300 ppm Cl−) and followed by surface analysis. The potential for pitting corrosion of pure Al was clearly shifted in the noble direction by the ECAP process indicating that this process improves resistance to pitting corrosion. The time dependence of corrosion potential and the anodic potential at 1 A·m−2revealed that the rate of formation of Al oxide films increased due to a decrease in the grain size of the Al after ECAP. Since there exists a negligible amount of impurity precipitates in pure Al, the improvement in pitting corrosion resistance of pure Al by ECAP appears to be attributable to an increase in the rate of formation of Al oxide films.

scholarly journals Improvement of Pitting-Corrosion Resistance of Ultrafine-Grained 7475 Al Alloy by Aging

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 360
Author(s):  
Ewa Ura-Bińczyk
Keyword(s):  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Al Alloy ◽  
Subsequent Aging ◽  
Fine Grained ◽  
Transmission Electron ◽  
Pitting Corrosion Resistance ◽  
Ultrafine Grained ◽  
Ultrafine Grained Microstructure

The effect of aging on the resistance to pitting corrosion of ultrafine-grained 7475 aluminium (Al) alloy processed by hydrostatic extrusion (HE) is studied. Differences in the microstructure were investigated using secondary electron (SEM) and transmission electron microscopy (TEM). Corrosion tests were performed in 0.1 M NaCl, and characterization of corroded surface was performed. The results of this work show that the pitting susceptibility of ultra-fine grained 7475Al is related to the distribution of MgZn2 precipitates. After HE, the formation of An ultrafine-grained microstructure at the grain boundaries of ultrafine grains is observed, while subsequent aging results in the formation of MgZn2 precipitates in the grain interior. Grain refinement increases susceptibility to localized attack, while the subsequent aging improves the overall corrosion resistance and limits the propagation of corrosion attack.

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