Monitoring pitting corrosion of AISI 316L austenitic stainless steel by acoustic emission technique: Choice of representative acoustic parameters

This experimental work was aimed at investigating the monitoring of pitting corrosion by the acoustic emission (AE) technique, for pits developed by p otentiostatic or galvanostatic polarization on two types of 316L austenitic stainless steels, in a 3% NaCl solution acidified to pH 2. The study of th e evolution of AE global activity during the test showed the existence of a time delay before pits became emissive. This time delay and the AE events number rate measured during the propagation step of the pits are closely co rrelated with the sensitivity of the material towards pitting and with the polarization procedure. Moreover, the evolution of cumulative % of AE signa ls number versus selected acoustic parameters shows that rise time and coun ts number of signals appear to be discriminating acoustic parameters for mo nitoring pitting corrosion of austenitic stainless steels by acoustic emiss ion technique in our experimental conditions, whatever the polarization pro cedure and the type of tested steel. (C) 2001 Kluwer Academic Publishers.