Correlative EBSD and SKPFM characterisation of microstructure development to assist determination of corrosion propensity in grade 2205 duplex stainless steel


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Oernek C. , Engelberg D. L.

JOURNAL OF MATERIALS SCIENCE, vol.51, no.4, pp.1931-1948, 2016 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 51 Issue: 4
  • Publication Date: 2016
  • Doi Number: 10.1007/s10853-015-9501-3
  • Title of Journal : JOURNAL OF MATERIALS SCIENCE
  • Page Numbers: pp.1931-1948

Abstract

Correlative electron backscatter diffraction (EBSD) and scanning Kelvin probe force microscopy (SKPFM) analysis has been carried out to characterise microstructure development and associated corrosion behaviour of as-received and 750 A degrees C heat-treated grade 2205 duplex stainless steel. High-resolution EBSD analysis revealed the presence of sigma- and chi-phase, secondary austenite, Cr2N, and CrN after ageing treatment. SKPFM Volta potential measurements confirmed the formation of discrete reactive sites, indicating local corrosion propensity in the microstructure. Cr2N, sigma-phase, and inter-granular chi-phase had the largest net cathodic activity, followed by CrN and intra-granular chi-phase showing medium electrochemical activity, with ferrite and austenite (including secondary austenite) showing net anodic activity. Corrosion screening confirmed selective corrosion of ferrite in the as-received and 750 A degrees C-aged conditions with the corrosion propensity of secondary phases staying in-line with SKPFM observations. Stress corrosion micro-cracks were also observed and are discussed in light of microstructure corrosion propensity.