In situ observation of local corrosion events with electrochemical AFM investigations

The combination of scanning force microscopic (AFM) und electrochemical inv estigations allowed the in situ observation of local corrosion events. An e xample for such events is the intergranular corrosion (IK) of austenitic st ainless steels. There is a clear relationship between the precipitation and intergranular corrosion behaviour of austenitic steels. The results of the EPR-Test verify this relationship. An improvement of the detection of incr easing intergranular corrosion susceptibility could be obtained by simple m odifications of the EPR test parameters. The test conditions for the electr ochemical in situ AFM investigations were found in pretests following the p rinciple of the EPR test. In situ AFM images of an intergranular attack wer e made by use of a special electrochemical cell. On this way local changes on the surface of the specimen can be observed in situ, that means during t he polarization.