Effect of Surface Roughness on Pitting Corrosion of AZ31 Mg Alloy
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Authors
Mitchell, Jeffrey
Crow, Natalie
Nieto, Andy
Subjects
magnesium
surface roughness
salt fog
pitting corrosion
surface roughness
salt fog
pitting corrosion
Advisors
Date of Issue
2020
Date
2020
Publisher
MDPI
Language
en_US
Abstract
Magnesium is a highly desired material for multiple applications including automotive, aircraft, and biomedical components due to its high strength to weight ratio, non-toxicity, and its good machinability. The main drawback of magnesium use is its poor resistance to corrosion. The goal of this experiment was to determine the effect of surface roughening treatments on the rate of corrosion and to characterize the resultant magnesium oxide (MgO) and brucite (Mg(OH)2) corrosion products. Three samples of AZ31 alloy with varying initial surface roughness were exposed to simulated marine conditions using a salt fog chamber for 672 h. The salt fog experiments used a 3.5 wt.% NaCl solution and were conducted in accordance with the ASTM B117 test protocols. One sample was tested in an as-received state, served as the control, another sample was roughened using a grit blaster, and another was polished to a mirror finish. Formed oxide scales were characterized using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy. The samples with a higher roughness underwent the severest corrosion and ensuing formation of the thickest oxide layers. The results indicate that the initial surface roughness has a profound effect on the resulting severity of pitting corrosion in Mg alloys and that mechanical polishing can substantially reduce the propensity for uniform and pitting corrosion to occur.
Type
Article
Description
The article of record as published may be found at https://doi.org/10.3390/met10050651
Series/Report No
Department
Operations Research (OR)
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Andy Nieto would like to acknowledge support from Naval Postgraduate School (NPS) Research Initiation Program (RIP) and the NPS Foundation SEED Program.
Funder
Format
12 p.
Citation
Mitchell, Jeffrey, Natalie Crow, and Andy Nieto. "Effect of Surface Roughness on Pitting Corrosion of AZ31 Mg Alloy." Metals 10.5 (2020): 651.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.