Effect of sensitisation on the atmospheric corrosion of Al-Mg alloys

Michael Lowden, Alison Davenport

Research output: Contribution to conference (unpublished)Paperpeer-review

Abstract

The effect of sensitisation on the atmospheric corrosion of AA5083 'O' temper was investigated under 0.5 µl NaCl droplets. At chloride deposition densities of 5500±600 μg/cm2 and 2000±200 μg/cm2 sensitisation increased the atmospheric corrosion rate of the alloy in weeklong experiments at 87% RH. Intergranular attack was the main type of corrosion observed in these experiments, in addition to pitting. Regions around pits or IGC sites were observed to become mildly acidic, due to hydrolysis that occurred. Beyond these regions net cathodes areas formed, which were darker and etched in appearance, due to possible increased local alkalinity. The relative size and frequency of these regions that formed also proved to be different in sensitised and as-received samples. The effect of sensitisation to the corrosion rate of the alloy was also more obvious under conditions of lower chloride deposition density. This was shown through a higher intergranular attack on the sensitised alloy surface, relative to minor attack on AA5083 in its 'O' tempered state. Droplet spreading behaviour also seemed to be influenced by the presence of corrosion product at the droplet edge, with the micro-droplets also observed to form around parent droplets.

Original languageEnglish
Publication statusPublished - 2017
EventJoint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017 - Prague, Czech Republic
Duration: 3 Sept 20177 Sept 2017

Conference

ConferenceJoint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017
Country/TerritoryCzech Republic
CityPrague
Period3/09/177/09/17

Bibliographical note

Publisher Copyright:
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. All rights reserved.

Keywords

  • Deposition density
  • Intergranular corrosion
  • NaCl droplets
  • Sensitisation

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Surfaces and Interfaces

Fingerprint

Dive into the research topics of 'Effect of sensitisation on the atmospheric corrosion of Al-Mg alloys'. Together they form a unique fingerprint.

Cite this