Study On Electrochemical Noise For Stress Corrosion Cracking Of C Ring Specimen

304 austenitic stainless steel and 800 Nickle-based alloys have been applied extensively owning to have good mechanical properties and corrosion resistance, but they will occur stress corrosion cracking in service. The reason for this is that media environment of heat transfer pipe is in high temperature alkalescence caused by impurity entering circulating water of heat transfer pipe two loop in steam generator of nuclear power plant. Under these conditions, 304 austenitic stainless steel and 800 Nickle-based alloys are prone to engender SCC. Because SCC occurs abruptly and can bring disaster consequence, more and more scientific researchers commit themselves to study induce cause and cracking law of SCC. So far SCC law and influencing factor have been investigated widely, but very little work on SCC inspection/detection are done. In recent 10 years, measure technique of electrochemical noise has gradually become one of the important means of local corrosion field. This paper is derected against 304 austenitic stainless and 800 Nickle-based alloys for nuclear electricity occurring SCC, some shallow studies are done using experimental method and analytical method of electrochemical noise technique and some significative achievement are gained. In the paper, electrolytic cell setting used to carry through SCC experiment and electrochemical testing was designed. The characteristic of the setting as follows, firstly, it does without enveloping C ring specimen; secondly, it can control effectively working area of working electrode; thirdly, working electrode can take down expediently from electrolytic cell setting; finally, it can carry through SCC experiment in heat heavy alkali solution. In 100℃50% NaOH solution, utilizing electrolytic cell setting designed carried through SCC experiment of 304 austenitic stainless steel. The experimental results indicate that, electrochemical noise technique can estimate emergence time of local corrosion. In addition, using electrochemical noise technique to inspect material corrosion types with different corrosion state in different media environment.Originality noise data gained through experiment were analysed. The result of analysis showed that characteristic of time domain and frequency domain from electrochemical noise and calculated parameters can estimate qualitatively corrosion speed and corrosion type of materials.