Stress corrosion cracking of sensitized AA5083 (Al-4.5Mg-1.0Mn)

J. L. Searles, P. I. Gouma, R. G. Buchheit

Research output: Contribution to journalConference articlepeer-review

40 Scopus citations

Abstract

AA5083 (Al-4.4Mg-0.7Mn-0.15Cr) is a non-heat treatable aluminum alloy known for its excellent corrosion resistance. However, it can become susceptible to intergranular stress corrosion cracking (IGSCC) when exposed to temperatures ranging from 50° to 200°C for sufficient lengths of time. In this study, IGSCC response of sensitized 5083 was studied by constant extension rate testing (CERT) in aerated 3.5%NaCl solution under free corrosion conditions and under potentiostatic polarization. To aid in interpreting the CERT results, precipitation of β (Al3Mg2) intermetallic particles on grain boundaries was characterized by transmission electron microscopy. Additionally, the dissolution characteristics of the β phase were measured by potentiodynamic polarization of the compound synthesized in bulk form. CERT results showed that under open circuit conditions, measured ductility depended strongly on sensitization time, reaching a minimum at 189 hours. This trend correlated well with the fractional coverage of β on grain boundaries. In polarization experiments, bulk synthesized β was found to be spontaneously passive from its corrosion potential (-1.40Vsce) up to about-0.92Vsce where passivity was observed to breakdown. In CERT, sensitized samples polarized below the β phase breakdown potential showed almost no evidence of IGSCC testing indicating that a high β dissolution rate is a requirement for IGSCC.

Original languageEnglish
Pages (from-to)1437-1442
Number of pages6
JournalMaterials Science Forum
Volume396-402
Issue number3
DOIs
StatePublished - 2002
EventAluminium Alloys 2002 Their Physical and Mechnaical Properties: Proceedings of the 8th International Conference ICAA8 - Cambridge, United Kingdom
Duration: Jul 2 2002Jul 5 2002

Keywords

  • 5083
  • Al-Mg alloys
  • AlMg
  • Anodic dissolution SCC
  • Constant extension rate testing
  • IGSCC
  • Sensitization
  • Stress corrosion cracking
  • β phase

ASJC Scopus subject areas

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

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