Kelvin Probe Force Microscopy and Atmospheric Corrosion of Cold-rolled Grade 2205 Duplex Stainless Steel

摘要

The effect of cold deformation on the corrosion behaviour of duplex stainless steelhas not been fully understood yet. The work reported in this paper addresses the effectof cold-roll reductions of up to 40% on microstructure development and corrosionbehaviour of grade 2205 duplex stainless steel. The deformation heterogeneity andmicrostructure after cold-rolling as a function of process direction has been analysedby electron backscatter diffraction (EBSD). These microstructures were then investigatedusing Kelvin Probe Force Microscopy (KPFM) and subsequently targeted withMgCl_2 salt-laden deposits to probe their corrosion performance in controlled atmosphericenvironment. In the as-received microstructure ferrite was preferentially attackedby selective dissolution, whilst austenite became more susceptible to localisedcorrosion with increasing cold deformation. Interestingly, Volta potential differencesmeasured between a Pt-probe and the surface also changed with the degreeof cold deformation. Volta potential hot-spots obtained by KPFM seemed to correlatewith regions containing local micro-deformation.