Detection of SCC initiation in austenitic stainless steel by electrochemical noise measurements

摘要

The electrochemical noise (EN) measurement technique is one of the most promising tools for continuous in situ corrosion monitoring in technical systems with a certain potential to be used for the detection of stress corrosion cracking (SCC). To evaluate the suitability of the EN technique for the detection of SCC initiation, a small but systematic test programme was started, performing EN measurements on type 304 austenitic stainless steel during constant extension rate tensile tests in aqueous thiosulphate solution at room temperature. SCC could be detected by EN measurements, which was verified by interruptions of the experiments at different stages, by testing steel with different degrees of sensitisation and by post-test fractography in the scanning electron microscope. Conclusions on the cracking mechanism could be drawn based on the current noise signal pattern.