The Effect of Solution-Annealing on the EIS Response of AISI 316 SS with Different Degrees of Sensitization in the Transpassive Region

摘要

In this study the effect of solution-annealing procedure on the corrosion behavior of the AISI 316 stainless steel (SS) with different degrees of sensitization (DOS) was investigated in the trans-passive region using Electrochemical Impedance Spectroscopy (EIS), electron microscopy and optical microscopy. The EIS response of the samples included three discrete regions in transpassive potential range namely 1 - anodic dissolution of the passive layer, 2 - the grain boundary dissolution and 3- the localized attack. The resistance to localized attack was better for the solution-annealed samples in comparison with as - received ones. In the case of as-received samples, the healing effect was observed above 600 degrees C sensitization temperature. The SEM and optical micrographs of the samples polarized to the trans-passive region showed grain boundary attack for all sensitized specimens.