Possibility of detection of crack initiation in high temperature water

Abstract

The initiation of stress corrosion cracks in sensitised austenitic stainless steel under high temperature water conditions (simulated boiling water reactor environment) was detected, applying electrochemical noise measurement technique. The stress corrosion cracks were generated on pre‐oxidised, unnotched standard tensile round bar specimens under constant load conditions. The elementary transients associated with stress corrosion crack initiation were found to be embedded in the basic noise pattern coming from the oxide growth reaction on the tensile specimen. Thus a simple calculation of standard deviations to identify localised corrosion phenomena under high temperature water conditions cannot be used. The changes in the track of power density spectra proved to be much more suitable to indicate stress corrosion crack initiation under high temperature water conditions.

An attempt to detect SCC by combined measurements of electrochemical noise and acoustic emission

“…The main result of this research was the conclusion that the rate of production of new material was proportional to the directly measured current. Furthermore, several studies performed on austenitic stainless steel under various conditions 12–18 have also indicated that it might be possible to measure electrochemical current and voltage noise fluctuations resulting from the initiation and propagation of SCC. Some authors 19 have used a similar approach on pre‐cracked coated CT specimens, and found certain oscillations in the measured current, presumably connected to the periodic propagation of the crack.…”

Corrosion monitoring techniques for detection of crack initiation under simulated light water reactor conditions

“…A significantly lower number of EN measurements have been performed under simulated LWR conditions during slow strain rate tensile (SSRT) or constant load tests with sensitised, solution annealed and proton irradiated stainless steels 14,[28][29][30][31][32][33][34][35] and with low alloy reactor pressure vessel steels. 36,37 Positive current transients, similar to those observed in room temperature tests, have been observed for intermediately sensitised stainless steel specimens loaded above the material yield stress.…”

Evaluation of 08CH18N10T stainless steel corrosion in subcritical water by electrochemical noise analysis

“…Liu et al [17] measured EN of the coupling current between two identical steel electrodes as a function of oxygen concentration, flow rate, temperature and pressure in subcritical and supercritical environment. Much work was directed towards the assessment of susceptibility of boiling water reactor (BWR) construction materials to intergranular stress corrosion [18][19][20][21]. In one of the pioneering studies, detailed analysis of current noise pulses and their association with different stages of intergranular stress cracks was performed [18].…”

“…Manahan et al [19] applied coupling current noise analysis for the identification of crack events in sensitized type 304 stainless steel. The objective of other studies [20,21] was to detect cracking initiation in slow strain rate tensile (SSRT) tests. Experiments were performed on sensitized austenitic steels in a simulated BWR environment.…”