Effect of equal channel angular pressing on the pitting corrosion resistance on the aluminum alloys with/without anodization

Hiroaki Nakano, In Joon Son, Satoshi Oue, Shigeo Kobayashi, Hisaaki Fukushima, Zenji Horita

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

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.

Original languageEnglish
Title of host publicationTHERMEC 2009
Pages1989-1994
Number of pages6
DOIs
Publication statusPublished - Feb 9 2010
Event6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009 - Berlin, Germany
Duration: Aug 25 2009Aug 29 2009

Publication series

NameMaterials Science Forum
Volume638-642
ISSN (Print)0255-5476

Other

Other6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009
CountryGermany
CityBerlin
Period8/25/098/29/09

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Nakano, H., Son, I. J., Oue, S., Kobayashi, S., Fukushima, H., & Horita, Z. (2010). Effect of equal channel angular pressing on the pitting corrosion resistance on the aluminum alloys with/without anodization. In THERMEC 2009 (pp. 1989-1994). (Materials Science Forum; Vol. 638-642). https://doi.org/10.4028/www.scientific.net/MSF.638-642.1989