SKPFM measured Volta potential correlated with strain localisation in microstructure to understand corrosion susceptibility of cold-rolled grade 2205 duplex stainless steel

Scanning Kelvin probe force microscopy (SKPFM) of annealed and cold-rolled grade 2205 duplex stainless steel has been correlated with microstructure analysis using electron back-scattered diffraction (EBSD). In annealed microstructure Volta potential differences indicated micro-galvanic coupling between ferrite and austenite reasoning selective dissolution of ferrite. The introduction of cold work reduced the difference between both phases, but the development of local extremes in Volta potential was observed. Microstructure analysis revealed the presence of larger misorientation concentrations at these sites, which can explain the changes in observed corrosion behaviour, from selective dissolution in the annealed condition to localised corrosion attack after cold-rolling.