SCC Susceptibility and Oxide Film Characteristics of Type 304 Stainless Steel under Controlled Potential in High-Temperature-High-Purity Water

In order to examine the anodic polarization characteristics of typical structural materials of boiling water reactors (BWRs), the anodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in deaerated high purity water at 553 K using the previously reported measurement method which was confirmed suitable for high temperature -high purity water. In order to specify which constituent element determines the dissolution characteristics of these materials, the anodic polarization curves of pure iron, pure nickel, and pure chromium were also surveyed. The anodic polarization curve of 316L SS was determined to have active, passive, and transpassive states which were the same as type 304 SS (304 SS) showed. But, Alloy 182 had different polarization characteristics especially near the corrosion potential as it had no active state. From comparison results of the polarization characteristics of these materials and their constituent elements, the corrosion characteristics of these materials were concluded to be mainly determined by the corrosion characteristics of chromium.

Section: Introductionmentioning

confidence: 99%

Determining factors for anodic polarization curves of typical structural materials of boiling water reactors in high temperature – high purity water

Tachibana

Ishida

Wada

et al. 2012

“…11 with some literature data. 5,7) In this measurement, the WE was replaced with a new polished one. The results were as follows.…”

Section: Anodic Polarization Curvementioning

confidence: 99%

“…Among those groups, only Hirayama et al 5) and Kim 7) measured the anodic polarization curve in deaerated pure water. Hirayama et al 5) superimposed a square wave alternation voltage on the potential applied to the working electrode and devised an IR compensation method by estimating solution resistance from the transient response of current. They used this approach to measure the anodic polarization curve in deaerated pure water at 563 K. Kim 7) used a micro-working electrode made of type 304 SS and a spiral counter Pt electrode to measure the anodic and cathodic polarization curves in pure water at 561 K by the galvanostatic method.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11] In order to calculate ECPs, the anodic polarization curve measured in deaerated pure water is necessary. Among those groups, only Hirayama et al 5) and Kim 7) measured the anodic polarization curve in deaerated pure water. Hirayama et al 5) superimposed a square wave alternation voltage on the potential applied to the working electrode and devised an IR compensation method by estimating solution resistance from the transient response of current.…”

Section: Introductionmentioning

confidence: 99%

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Study of Polarization Curve Measurement Method for Type 304 Stainless Steel in BWR High Temperature-High Purity Water

Tachibana

Ishida

Wada

et al. 2009

In order to improve the accuracy of electrochemical corrosion potential (ECP) calculations, information about the effects of the flow velocity, the type of oxidization species, the oxide film thickness, and the oxide film classification on the polarization curve is needed. Polarization curve measurements were studied here with that information goal in mind. A wire-shaped working electrode was employed to remove the IR drop caused by high solution resistance, which makes it difficult to apply a proper potential to the working electrode. In order to measure the static state current, the potential scanning condition was optimized. It was confirmed that a steady-state current can be measured by establishing a potential scanning rate for applying a potential not greater than 0.01 mVÁs À1 with a step-shaped waveform. This method was employed to measure the anodic polarization curve of type 304 stainless steel in deaerated 553 K high-purity water. The passivation behavior was clearly observed. Also, the cathodic polarization curves in water containing dissolved oxygen of less than 1000 ppb were measured. The oxygen concentration dependence of ECP was calculated from measured polarization curves. The ECPs calculated using the measured polarization curves were in good agreement with those measured with an electrometer, confirming the validity of the measured polarization curves.

Development of Analytical Method and Study about Microstructure of Oxide Films on Stainless Steel

Nemoto

Miwa

Kikuchi

et al. 2002

To study about microstructure and chemical composition of oxide films formed on surface of stainless steel is most important for understanding of stress corrosion cracking (SCC) and irradiation assisted stress corrosion cracking (IASCC). In this work, a new sample preparation method for microstructure observation of oxide films was developed. To prevent to break oxide films during fabrication, surface of specimens were protected with plating. Focused ion beam (FIB) processing was conducted to prepare thin foil samples of cross section of oxide films. After sample preparation, microstructure of cross section of oxide films was observed by transmission electron microscope (FE-TEM), and microscopic chemical composition was analyzed by energy dispersed X-ray spectrometer (EDS). From the results, effects of silicon (Si) doping for oxide film formation in two oxidation conditions are discussed.