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.

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

CORROSION ◽  
10.5006/3335 ◽  
2019 ◽  
Vol 76 (1) ◽  
pp. 51-62
Author(s):  
Mary E. Parker ◽  
Robert G. Kelly
Keyword(s):  
Aluminum Alloys ◽  
Atmospheric Corrosion ◽  
Salt Spray ◽  
High Strength ◽  
Corrosion Testing ◽  
Short Exposure ◽  
Wetting And Drying ◽  
Short Exposure Time ◽  
High Strength Aluminum Alloys ◽  
Dwell Period

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.

Research on the Influence of Salt Fog Corrosion Behavior of 6005A Aluminum Alloy Welded Joints by Environment Humidity

2013 ◽  
Vol 662 ◽  
pp. 251-257
Author(s):  
Ning Xia ◽  
Zhi Min Zhu ◽  
Hui Chen
Keyword(s):  
Weight Loss ◽  
Tensile Strength ◽  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Relative Humidity ◽  
Corrosion Rate ◽  
Environmental Humidity ◽  
Welding Joints ◽  
Salt Fog Corrosion ◽  
Salt Fog

6005A aluminum alloys were welded at different relative humidity conditions. The effects of relative humidity on the salt fog corrosion of the welding joints were researched. The results showed that the weight loss of the joints after 14 days corrosion was higher than that corroded after 7days, but the corrosion rate was lower. The corrosion rate first increased then declined with the increase of environmental humidity for the joints corroded for 7days. However, when the environmental humidity was 80%, corrosion rate achieved the maximum, when environment humidity was 70%, corrosion rate was the lowest. After corroded for 14 days, corrosion rate was the maximum when the environmental humidity was 50%, and it was the lowest when the environmental humidity was 90%. The tensile strength declined obviously after corrosion.

scholarly journals Prediction of atmospheric corrosion from meteorological parameters: Case of the atmospheric basin of the Costa Rican Western Central Valley

2021 ◽  
Author(s):  
Javier Rodríguez-Yáñez ◽  
Erick Rivera-Fernández ◽  
Daniel Alvarado-González ◽  
Mariela Abdalah-Hernández ◽  
Rafael Quirós-Quirós
Keyword(s):  
Relative Humidity ◽  
Corrosion Rate ◽  
Atmospheric Corrosion ◽  
Meteorological Parameters ◽  
Central Valley ◽  
Costa Rican ◽  
Atmospheric Pollutants ◽  
Empirical Equations ◽  
Atmospheric Parameters ◽  
Study Region

The assessment of atmospheric corrosion is currently based on studies of atmospheric basins (AB). The models applied to the estimation of atmospheric corrosion imply measurements of several meteorological and atmospheric pollution parameters, which make the estimation complex. The main meteorological parameters to be considered in tropical atmospheric corrosion are associated with temperature (T) and relative humidity (RH). These parameters are also included in the calculation of the time of humidification (TDH). In addition, the atmospheric pollutants associated with corrosion are chloride (Cl) and sulphur dioxide (SO2). The Western Central Valley (WCV) in Costa Rica is a low-pollution AB; therefore, it is possible to employ simplified atmospheric corrosion models based on few atmospheric parameters. The meteorological parameters of the study region were analyzed in terms of their dependence on altitude and their applicability in simplified empirical equations of the corrosion rate (Vcorr) for the WCV. These simple relations were compared with the model proposed by the ISO 9223-2012 standard.

CORROSION RESISTANCE OF THE BRAZED JOINTS OF THE GTE FUEL MANIFOLDS, MADE WITH VARIOUS BRAZING ALLOYS

2021 ◽  
pp. 23-33
Author(s):  
A.V. Sviridov ◽  
◽  
A.N. Afanasyev-Khodykin ◽  
I.A. Galushka ◽  
◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Gas Turbine ◽  
Salt Spray ◽  
Corrosion Damage ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Spray Chamber ◽  
Corrosion Resistant ◽  
Research Results ◽  
Brazed Joints

Presents the results of work on assessing the corrosion resistance of brazed joints of corrosion-resistant steels used in the manufacture of fuel manifolds for gas turbine engines in a salt spray chamber. The main types of corrosion damage of brazed joints made with brazing alloys of various types (based on copper and nickel) have been identified. The influence of the type of brazing alloy and the grade of the brazed materials on the nature of corrosion damage to brazed joints is determined. Based on the research results, assumptions have been made about the mechanism of occurrence and development of corrosion damage in brazed joints of various materials.

Effect of Thickness of Water Film on Atmospheric Corrosion Behavior of Carbon Steel

2005 ◽  
Vol 475-479 ◽  
pp. 221-224
Author(s):  
Yuji Hosoya ◽  
Tadashi Shinohara ◽  
Shin-ichi Motoda ◽  
Wataru Oshikawa
Keyword(s):  
Carbon Steel ◽  
Relative Humidity ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Atmospheric Corrosion ◽  
Water Film ◽  
Adsorbed Water ◽  
Sea Salt ◽  
Adsorbed Water Film

Atmospheric corrosion for carbon steel was discussed with taking notice of the relation between the corrosion rate, CR, and the thickness of adsorbed water film, d, onto deposited sea salt. Amount of water adsorbed onto sea salt was measured under various conditions of amount of deposited sea salt, Ws, and relative humidity, RH. Derived concentration of the solution film was compared with that calculated thermodynamically. Corrosion amount of carbon steel specimens exposed for a month under various Ws and RH was measured and CR along with d were obtained for each condition. The relations of CR to d had the same tendency as is found on “moist corrosion” and “wet corrosion” in Tomashov’s model; However, it showed a maximum CR = 0.29mm/y at d = 56µm, thicker than that reported by Tomashov.

Paper 1: Corrosion Inhibitors as Additives to Highway De-Icing Salts-Laboratory Tests

1967 ◽  
Vol 182 (10) ◽  
pp. 124-148
Author(s):  
R. R. Bishop ◽  
D. E. Steed
Keyword(s):  
Corrosion Rate ◽  
Rock Salt ◽  
Corrosion Inhibitors ◽  
Salt Spray ◽  
Corrosion Damage ◽  
The United States ◽  
Motor Vehicles ◽  
The Road ◽  
Paint Systems ◽  
Bare Steel

Up to a million tons of rock salt are spread on the roads of England and Wales during a severe winter. It has frequently been suggested that this salt causes increased corrosion damage to motor vehicles. In North America and Scandinavia considerable interest has been shown in the use of corrosion inhibitors as additives to highway de-icing salts and at least two inhibited salts are marketed in the United States. Use of an intermittent salt spray test in the Road Research Laboratory (R.R.L.) has shown that a 3 per cent rock salt solution is about 13 times more corrosive than urban rainwater to bare steel. Polyphosphate and chromate type inhibitors were examined under these test conditions and were found largely ineffective in reducing the corrosion rate of bare steel. However, the polyphosphate inhibitor showed a large reduction in corrosion rate of damaged painted panels finished in current motor primers and full paint systems. The work is continuing.

scholarly journals REVISITING THE CONFIRMATION OF THE IDENTITY OF THE CORROSION DESTRUCTION MECHANISM OF ALUMINUM ALLOYS (review) Part 1. Atmospheric corrosion

2020 ◽  
pp. 86-94
Author(s):  
M.G. Abramova ◽  
Keyword(s):  
Aluminum Alloys ◽  
Surface Morphology ◽  
Atmospheric Corrosion ◽  
Corrosion Damage ◽  
Corrosion Products ◽  
Natural Conditions ◽  
Accelerated Methods ◽  
Destruction Mechanism ◽  
Kinetics Of ◽  
Corrosion Research

The paper presents a review of accelerated methods of corrosion research of aluminum alloys; the destruction mechanism in these methods is similar with that one in corrosion in natural conditions. The kinetics of the development of corrosion processes, the correspondence of absolute values of corrosion damage, their types and degree of development, the nature of corrosion damage and surface morphology, the nature of the fracture, and the analysis of the composition of corrosion products are considered as criteria of identity.

scholarly journals A Study of Moist Air Condensation Characteristics in a Transonic Flow System

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4052
Author(s):  
Jie Wang ◽  
Hongfang Gu
Keyword(s):  
Mach Number ◽  
Relative Humidity ◽  
Transonic Flow ◽  
Flow System ◽  
Plane Surface ◽  
Droplet Growth ◽  
Moist Air ◽  
Dry Air ◽  
Hydraulic Equipment ◽  
Non Equilibrium

When water vapor in moist air reaches supersaturation in a transonic flow system, non-equilibrium condensation forms a large number of droplets which may adversely affect the operation of some thermal-hydraulic equipment. For a better understanding of this non-equilibrium condensing phenomenon, a numerical model is applied to analyze moist air condensation in a transonic flow system by using the theory of nucleation and droplet growth. The Benson model is adopted to correct the liquid-plane surface tension equation for realistic results. The results show that the distributions of pressure, temperature and Mach number in moist air are significantly different from those in dry air. The dry air model exaggerates the Mach number by 19% and reduces both the pressure and the temperature by 34% at the nozzle exit as compared with the moist air model. At a Laval nozzle, for example, the nucleation rate, droplet number and condensation rate increase significantly with increasing relative humidity. The results also reveal the fact that the number of condensate droplets increases rapidly when moist air reaches 60% relative humidity. These findings provide a fundamental approach to account for the effect of condensate droplet formation on moist gas in a transonic flow system.

scholarly journals Sacrificial Dissolution of Zinc Electroplated and Cold Galvanized Coated Steel in Saline and Soil Environments: A Comparison

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 744
Author(s):  
Ameeq Farooq ◽  
Umer Masood Chaudry ◽  
Ahsan Saleem ◽  
Kashif Mairaj Deen ◽  
Kotiba Hamad ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Saline Soil ◽  
Steel Substrate ◽  
Salt Spray ◽  
Steel Structures ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Transfer Resistance ◽  
Soil Solutions

To protect steel structures, zinc coatings are mostly used as a sacrificial barrier. This research aims to estimate the dissolution tendency of the electroplated and zinc-rich cold galvanized (ZRCG) coatings of a controlled thickness (35 ± 1 μm) applied via brush and dip coating methods on the mild steel. To assess the corrosion behavior of these coated samples in 3.5% NaCl and 10% NaCl containing soil solutions, open circuit potential (OCP), cyclic polarization (CP), and electrochemical impedance spectroscopy (EIS) tests were performed. The more negative OCP and appreciably large corrosion rate of the electroplated and ZRCG coated samples in 3.5% NaCl solution highlighted the preferential dissolution of Zn coatings. However, in saline soil solution, the relatively positive OCP (>−850 mV vs. Cu/CuSO4) and lower corrosion rate of the electroplated and ZRCG coatings compared to the uncoated steel sample indicated their incapacity to protect the steel substrate. The CP scans of the zinc electroplated samples showed a positive hysteresis loop after 24 h of exposure in 3.5% NaCl and saline soil solutions attributing to the localized dissolution of the coating. Similarly, the appreciable decrease in the charge transfer resistance of the electroplated samples after 24 h of exposure corresponded to their accelerated dissolution. Compared to the localized dissolution of the electroplated and brush-coated samples, the dip-coated ZRCG samples exhibited uniform dissolution during the extended exposure (500 h) salt spray test.

scholarly journals The Influence of Surface Preparation of the Steel during the Renovation of the Car Body on Its Corrosion Resistance

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 384
Author(s):  
Dariusz Ulbrich ◽  
Jakub Kowalczyk ◽  
Arkadiusz Stachowiak ◽  
Wojciech Sawczuk ◽  
Jaroslaw Selech
Keyword(s):  
Corrosion Resistance ◽  
Glass Bead ◽  
Salt Spray ◽  
Zinc Coating ◽  
Surface Preparation ◽  
The Other ◽  
Average Thickness ◽  
Spray Chamber ◽  
Car Body ◽  
Abrasive Blasting

The article presents the influence of the applied method used for removing the varnish coat on the corrosion resistance of the car body sheet. The tests were carried out on samples prepared from factory-painted car body elements with pearlescent, metallized and acrylic varnish. Removal of the varnish coat was performed by sandpaper grinding, glass bead blasting, disc blaze rapid stripping, soda blasting and abrasive blasting with plastic granules. The average thickness of the factory-painted coating depending on the type of lacquer ranged from about 99 to 140 µm. On the other hand, after removing the varnish, the thickness of the protective zinc coating ranged from 2 to 12.7 µm. The highest values of the zinc coating were obtained for samples in which the varnish was removed by the method such as soda blasting and abrasive blasting with plastic granules. For these two methods of surface preparation, the damage to the zinc layer protecting the steel against corrosion is the smallest and the percentage of zinc in the surface layer ranges from 58% to 78%. The final stage of the research was to test the samples after removing the varnish coat in a two-hour exposure to the corrosive environment in a salt spray chamber. Samples with the surface prepared by grinding with sandpaper reached the level of surface rusting Ri 5, while in the case of soda blasting and the use of plastic granules, no corrosion centers were observed on the surface of the car body sheet.

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