Combination of Electrochemical Noise and Acoustic Emission for Analysis of the Pitting Corrosion Behavior of an Austenitic Stainless Cast Steel

The pitting corrosion behavior of a high alloy cast steel is analyzed in a sodium chloride solution by combination of the electrochemical noise technique and the acoustic emission (AE) method. Four corrosion states are identified on the steel surface after the 70 h noise measurement test. The simultaneously monitored AE exhibits two types of acoustic signals. The first type of AE events is attributed to the local passive oxide breakdown and the pit initiation process and the second type of AE events is related to the subsequent associated hydrogen gas bubble evolution.