Acoustic Emission of Hydrogen Bubbles on the Counter Electrode during Pitting Corrosion of 304 Stainless Steel

Abstract

An acoustical investigation into the hydrogen bubbles on the counter electrode during pitting corrosion of 304 stainless steel has been carried out with the potentiodynamic method. After reaching the pitting potential, there was a short time delay before an Acoustic Emission (AE) signal was detected. Given this, the obtained cumulative AE counts were divided into three distinct stages showing their own unique behavior in terms of rise time and duration. The bubble evolution characteristic in each different stage was supposed to be responsible for the feature of AE signal. In the AE Stage III, the cumulative counts of the AE signals provided empirical correlations with both the total number and the total volume of corrosion pits, thus demonstrating the potential of utilizing the AE signal of hydrogen bubble on the counter electrode as a non-intrusive monitoring tool of pitting corrosion.