Research Information System
JOURNAL OF MATERIALS SCIENCE, vol.51, no.4, pp.1931-1948, 2016 (SCI-Expanded)
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.