Simultaneous Monitoring of Acoustic Emission and Corrosion Potential Fluctuation for Mechanistic Study of Chloride Stress Corrosion Cracking
Both the acoustic emission (AE) and corrosion potential fluctuation were monitored for chloride stress corrosion cracking (SCC) of sensitized Type-304 stainless steel plate under bi-axial stress states. Branched SCCs were produced from rectangular-shaped corrosion pits initiated by falling-off of surface grains and filled with chromium oxide in 30mass% MgCl2 solution (363K). Both the AE and potential fluctuation were simultaneously detected during pit formation and SCC growth. Two types of AE (Type-I and Type-II) were monitored. Type-I AEs with higher frequency components were detected during the pit growth and supposed to be produced by falling-off of surface grains due to intergranular attack, while a number of Type-II AEs (approximately 12,500 counts) with low frequency components were detected during SCC propagation and supposed to be produced by cracking of the chromium oxy-hydroxides. Though the AEs detected during SCC test are not always the primary AEs from the SCC itself, secondary AEs can be usefully utilized to monitor the SCC initiation and propagation as well as the corrosion potential fluctuation.
Seung-Seok Lee, Joon Hyun Lee, Ik Keun Park, Sung-Jin Song, Man Yong Choi
A. Yonezu et al., "Simultaneous Monitoring of Acoustic Emission and Corrosion Potential Fluctuation for Mechanistic Study of Chloride Stress Corrosion Cracking", Key Engineering Materials, Vols. 321-323, pp. 254-259, 2006