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 steel has not been fully understood yet. The work reported in this paper addresses the effect of cold-roll reductions of up to 40% on microstructure development and corrosion behaviour of grade 2205 duplex stainless steel. The deformation heterogeneity and microstructure after cold-rolling as a function of process direction has been analysed by electron backscatter diffraction (EBSD). These microstructures were then investigated using Kelvin Probe Force Microscopy (KPFM) and subsequently targeted with MgCl_2 salt-laden deposits to probe their corrosion performance in controlled atmospheric environment. In the as-received microstructure ferrite was preferentially attacked by selective dissolution, whilst austenite became more susceptible to localised corrosion with increasing cold deformation. Interestingly, Volta potential differences measured between a Pt-probe and the surface also changed with the degree of cold deformation. Volta potential hot-spots obtained by KPFM seemed to correlate with regions containing local micro-deformation.