Study on Pitting Corrosion of Storage Tank Bottom Steel in Acidic Condition Using Acoustic Emission

摘要

The pitting corrosion of atmospheric storage tank (AST) bottom steel specimens was studied bycombined using acoustic emission (AE) and electrochemical polarization techniques in acidic NaClsolution. The AE signal characteristic parameters including amplitude, energy, hits, duration time andrise time varied over time, and the relationship between them were analyzed in each stage of pittingcorrosion process. The AE parameters and electrochemical polarization curve in time domain werealso compared. The result shows that the AE activity is consistent with that of potentiodynamicpolarization. The AE signal features are remarkably different in oxidized film rupture, pits propagationand corrosion products movement of the pitting stage. Extracting these AE signal features will be ofgreat help for diagnosing the corrosion severity and identifying the corrosion type of the AE on-linestorage tank bottom inspection, and further to assess the corrosion degree of the whole storage tankbottom.