Improved Atmospheric Corrosion Testing for Aluminum Alloys, Part II: Developing Improved Testing Protocol

A modified version of ASTM G85-A2 was developed in this work with the intention of targeting a relative humidity (RH) of 75% during the dwell period. The outcome was two different RH profiles, one that averaged 74% RH during the dwell period and another that averaged 61.5% RH during the dwell period. Both tests produced moderate exfoliation in AA2060-T3 after just 12 days of exposure. Other high-strength aluminum alloys (AA7075, AA2024) were exposed to the modified RH profiles, and both tests could correctly differentiate exfoliation resistance for these alloys. An average RH between 74% and 61.5% during the dwell period was found to produce consistent exfoliation ratings after a short exposure time. Electrochemical measurements made during salt spray testing were used to propose electrochemical mechanisms that occur during wetting and drying in atmospheric corrosion testing.

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Improved Atmospheric Corrosion Testing for Aluminum Alloys, Part I: Deconstructing ASTM G85-A2

CORROSION ◽

10.5006/3334 ◽

2019 ◽

Vol 76 (1) ◽

pp. 39-50

Author(s):

Mary E. Parker ◽

Robert G. Kelly

Keyword(s):

Aluminum Alloys ◽

Relative Humidity ◽

Corrosion Rate ◽

Atmospheric Corrosion ◽

Salt Spray ◽

Corrosion Damage ◽

Spray Chamber ◽

Testing Environment ◽

Dry Air ◽

Dwell Period

In this work, the testing environment generated during ASTM G85-A2 exposure was deconstructed for two different commercial salt spray chambers. It was found that relative humidity (RH) control was critical to obtaining consistent results among different salt spray chamber designs, and seemingly small differences in chamber operation could have a significant impact on RH and associated corrosion damage. When RH was too high during the dwell period of the wet-dry cycle, rinsing of the sample prevented the accumulation of corrosion products along grain boundaries, which was necessary for exfoliation formation. When RH during the dwell period was too low, local anodes stifled during the dry air purge and corrosion rate was very low for most of the repeating 6 hour cycle. This work was the first in a two part study.

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The Effect of Microstructure on the Properties of High Strength Aluminum Alloys

10.21236/ada133997 ◽

1983 ◽

Author(s):

Edgar A. Starke ◽

Keyword(s):

Aluminum Alloys ◽

High Strength ◽

High Strength Aluminum Alloys ◽

Effect Of Microstructure

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Surface Modification of Aluminum 6061-O Alloy by Plasma Electrolytic Oxidation to Improve Corrosion Resistance Properties

Coatings ◽

10.3390/coatings11010004 ◽

2020 ◽

Vol 11 (1) ◽

pp. 4

Author(s):

Dmitry V. Dzhurinskiy ◽

Stanislav S. Dautov ◽

Petr G. Shornikov ◽

Iskander Sh. Akhatov

Keyword(s):

Corrosion Resistance ◽

Aluminum Alloy ◽

Aluminum Alloys ◽

Plasma Electrolytic Oxidation ◽

Electrochemical Impedance ◽

High Strength ◽

Electrolytic Oxidation ◽

Coating Layers ◽

Plasma Electrolytic ◽

High Strength Aluminum Alloys

In the present investigation, the plasma electrolytic oxidation (PEO) process was employed to form aluminum oxide coating layers to enhance corrosion resistance properties of high-strength aluminum alloys. The formed protective coating layers were examined by means of scanning electron microscopy (SEM) and characterized by several electrochemical techniques, including open circuit potential (OCP), linear potentiodynamic polarization (LP) and electrochemical impedance spectroscopy (EIS). The results were reported in comparison with the bare 6061-O aluminum alloy to determine the corrosion performance of the coated 6061-O alloy. The PEO-treated aluminum alloy showed substantially higher corrosion resistance in comparison with the untreated substrate material. A relationship was found between the coating formation stage, process parameters and the thickness of the oxide-formed layers, which has a measurable influence on enhancing corrosion resistance properties. This study demonstrates promising results of utilizing PEO process to enhance corrosion resistance properties of high-strength aluminum alloys and could be recommended as a method used in industrial applications.

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Accelerated discovery of high-strength aluminum alloys by machine learning

Communications Materials ◽

10.1038/s43246-020-00074-2 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

Jiaheng Li ◽

Yingbo Zhang ◽

Xinyu Cao ◽

Qi Zeng ◽

Ye Zhuang ◽

...

Keyword(s):

Machine Learning ◽

Aluminum Alloys ◽

Mechanical Performance ◽

High Strength ◽

Cost Effective ◽

Alloy System ◽

Processing Route ◽

Specific Strength ◽

Cu Alloy ◽

High Strength Aluminum Alloys

Abstract Aluminum alloys are attractive for a number of applications due to their high specific strength, and developing new compositions is a major goal in the structural materials community. Here, we investigate the Al-Zn-Mg-Cu alloy system (7xxx series) by machine learning-based composition and process optimization. The discovered optimized alloy is compositionally lean with a high ultimate tensile strength of 952 MPa and 6.3% elongation following a cost-effective processing route. We find that the Al8Cu4Y phase in wrought 7xxx-T6 alloys exists in the form of a nanoscale network structure along sub-grain boundaries besides the common irregular-shaped particles. Our study demonstrates the feasibility of using machine learning to search for 7xxx alloys with good mechanical performance.

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