The crevice former which does not release anion impurities (e.g. Cl-) for SCC (Stress Corrosion Cracking) initiation experiment in simulated boiling water reactor water environment has been ev aluated. The creviced bent beam tests of sensitized stainless steel with using the crevice condition as an experimental parameter were carried out. Even SCC occurred at the part of specimen su rface which tested with only the spacer (no crevice former), it has been difficult to obtain the reproducible result. SCC ini...
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Evaluation of crevice former for SCC initiation experiment in simulated BWR water environment

The method for determining the repassivation potential for corrosion crevice of stainless steel is defined by JIS, but that of Alloy600 is not defined yet. In this paper, the method for determining the repassivation potential was considered based on the experiments with Alloy600 of nuclear constituent material by reference to JIS and intended to contribute to the establishment of it. In preparation for measuring the repassivation potential, the pitting potential dependence of Cl- concentration is measu...
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Study on the electrochemical method for determining the repassivation potential for corrosion crevice of Alloy600.

Crevice corrosion has been concerned in the Fukushima Daiichi Nuclear Power Station, since seawater was injected to make up water level as part of the emergency action. To evaluate structural integrity, it is important to inves tigate whether crevice corrosion occurred. The purpose of this study is to investigate conditions of crevice corrosion initiation and repassivation of SUS304L. SUS304L specimens with acrylic crevice were held at constant electr ochemical potentials in 1000ppm Cl- solution. It was in...
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Evaluation of crevice corrosion initiation condition and repassivation condition of SUS304L

Austenitic stainless steel welds typically have duplex microstructure with a few to over 10 ％ of 8-ferrite in austenite to prevent hot cracking during solidification. Therefore, austenitic stainless steel welds are also susceptible to thermal aging embrittlement similar with cast duplex stainless steels (CDSSs). Although microstructural morphologies of 8-ferrite in austenitic stainless steel welds is different from that of CDSSs, the effect of that on an thermal aging embrittlement behavior is not fully kno...
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Effect of thermal aging on impact behavior of austenitic stainless steel welds

Austenitic stainless steels are widely used as structural materials in many industries. However, stainless steels are susceptible to crevice corrosion in the solution including chloride ions. In this paper, at first, the most inhibitive anion against corrosion was investigated by anodic polarization measurement of type 316L stainless steel in the solution containing Cl- with candidate inhibitive anions (WO42-, MoO42-, VO3-). MoO42- was adopted as the most inhibitive anion in this study. Next, the effec...
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Effect on critical potentials for crevice corrosion initiation and repassivation of stainless steel by addition of inhibitive anion

Flow Acceleration Corrosion (FAC) is one of the mechanisms of pipe wall thinning in power plants. The wall thinning caused by FAC is usually found between 90 ℃ and 230 ℃ with a peak at about 150 ℃. However, FAC has been reported at temperatures below this range. This study evaluated the effect of DO and Cr content on wall thinning rate at 50 ℃. Raman spectroscopy was performed to identify the constituent species of the oxide film. FAC rate was seen to decrease by increasing Cr content. In terms of DO, wall ...
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Combined Effect of Cr content and Dissolved Oxygen Concentration on Wall Thinning Rate by Low Temperature FAC

Stress corrosion cracking (SCC) behavior of low-carbon stainless steel welds in high temperature water has been discussed with special attention on relation to the characteristics of microstructure. To investigate the effect of .-ferrite on SCC behavior, simulated heat-affected zone (partially melted zone) microstructure, where .-ferrite islands were widely distributed on grain boundary, was made by induction heating up to just below melting point. From the results of constant strain SCC test in high ...
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Effect of .-ferrite on stress corrosion cracking behavior of low-carbon stainless steel weld in high temperature water

When crevice corrosion occurs in Cl- containing solutions, Cl- concentration in the crevice increases by a few orders of magnitude due t o potential gradient. This is one of the reasons why localized corrosion takes place in a crevice. If there are non-aggressive anions ( such as MoO42-) coexist in the bulk with Cl-,it is expected that the non-aggressive anions migrate into the crevice competitively with C l- and it helps to improve the crevice environment. The purpose of this study is to investigate the e...
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Effects of non-aggressive anions as a mitigation measure to crevice corrosion in a chloride containing environment

Abstract: Crevice corrosion was occurred at the adsorption tower with silver impregnated carbon of Advanced Liquid Processing System (ALPS). The influence of silver impregnated activated carbon on crevice corrosion of 316L stainless steel was investigated by corrosion test and electrochemical measurement. Crevice corrosion was observed on the specimen tested with the activated carbon. On the other hand, no corrosion was observed on that without the activated carbon in both pH7.4 and pH12 solution (art...
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Influence of activated carbon on crevice corrosion in adsorption tower of Advanced Liquid Processing System (ALPS)

Potentiostatic etching method has been suggested as a technique for detection of pre-existing plastic st rain of type 316 stainless steel which is strained at 250°C that is a temperature assumed nuclear reacto r water. After potentiostatic etching (1N HNO3, -600mVSCE, 20min, 35°C), slip lines appear as etched lin es on the surface of specimen, and their density has one-to-one correlation with pre-existing strain. Th is method has a high sensitivity and can detect at least 1% plastic strain. However, it is ...
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Optimizing electrochemical potential and exposure time for the detection method of plastic strain in austenitic stainless steels by potentiostatic etching