Electrochemical noise generated during stress corrosion cracking (SCC) of type 304 stainless steel (UNS S30400) and α-brass were studied. Noise patterns showed common characteristics (i.e., a quick drop and slow recovery of the potential). The quick drop corresponded to the initiation of localized events where fresh metal was exposed. The slow recovery corresponded to the repassivation process of the exposed bare metal. The potential drop rate and recovery rate were almost constant during the SCC process for a given SCC system. For random noise, rates of potential rise and drop were similar. Frequency of the noise generated during SCC increased with an increase in applied stress. SCC initiation could be monitored and determined according to noise characteristics and distribution. Since the shift of background potentials had an obvious influence on characteristics of power spectrum density (PSD), the direct current (DC) component should be removed before analysis. Changes in standard deviation and PSD plateau with time could be used as criteria for monitoring SCC initiation.

Subject
Magnesium chloride, Electrochemical noise, Repassivation potentials, Crack initiation, Corrosion initiation, Stress cracking, Stress, Electric potential, Localized corrosion, Fracture, Stress corrosion cracking, Electrode potential, Samples
Keywords:
electrochemical noise, monitoring, power spectral density, repassivation, stainless steel, standard deviation, stress corrosion cracking, type 304 stainless steel, UNS S30400
NACE International
1999
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