Electrical mapping of AISI 304 stainless steel subjected to intergranular corrosion performed by means of AFM–LIS in the contact mode

The paper presents results of the AFM-based approach to local impedance spectroscopy (LIS) measurements performed in a 20 × 20 μm grid within an austenite grain–grain boundary region for sensitized AISI 304 stainless steel (SS). Maps of electrical parameters obtained on the basis of localized impedance spectra were demonstrated, presenting their changes and correlation with the sample topography. Performed research revealed significant differences in the electrical distribution of the contact resistance considered as the passive layer resistance and contact capacitance considered as the passive layer capacitance determined for austenite grain interiors and austenite grain boundaries affected by intergranular corrosion.

► Electrical differentiation of the austenite grain interior and its grain boundary. ► Austenite grains revealed higher localized impedance than its grain boundaries. ► Demonstration of electrical maps of the passive layer resistance and the passive layer capacitance. ► Relative changes of these parameters were determined within the localized grid.