Acoustic emission during the electrochemical corrosion of 304 stainless steel in H2SO4 solutions

Acoustic emission (AE) behaviour during the electrochemical corrosion of 304 stainless steel (304SS) in H2SO4 solutions was studied. AE signals which related to transpassive dissolution are detected in solutions with low pH, and are very slightly influenced by current density and pre-strain. During hydrogen bubble evolution, a weak correlation exists between the AE signal amplitude and the hydrogen bubble diameter. The concept of potential – pH – AE diagram is proposed and such a diagram is drawn based on AE activity and b-values. The main mechanisms of AE sources which are transpassive dissolution and hydrogen bubble evolution, are also discussed.

Research highlights
► AE signals during transpassive dissolution process are detectable in low pH solution.
► An E–pH–AE diagram is drawn based on AE activity and b-value.
► The change of stress condition of the specimen is the AE source mechanism of H2 bubbles evolution.