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Igarashi, Takahiro; Komatsu, Atsushi; Motooka, Takafumi*; Ueno, Fumiyoshi; Yamamoto, Masahiro
Corrosion Science and Technology, 20(3), p.105 - 111, 2021/06
We constructed three dimensional computational model using cellular automata method to simulate the intergranular corrosion propagation of stainless steel. In the model, the computational system was constructed by three types of cells: grain (bulk), grain boundary (GB), and solution cell. Our simulations revealed that the surface roughness calculated by the model adopted distributed dissolution rates of GBs was greater than that adopted constant dissolution rates of GBs. The cross-sectional images obtained by our simulation were comparable with that obtained by corrosion tests. These results indicate that the surface roughness during corrosion relates the distribution of corrosion rate.
Uchida, Shunsuke*; Hanawa, Satoshi; Naito, Masanori*; Okada, Hidetoshi*; Lister, D. H.*
Corrosion Engineering, Science and Technology, 52(8), p.587 - 595, 2017/10
Times Cited Count：4 Percentile：19.16(Materials Science, Multidisciplinary)Based on the relationship among ECP, metal surface conditions, exposure time and other environmental conditions, a model to evaluate the ECP and corrosion rate of steel was developed by coupling a static electrochemical analysis and a dynamic oxide layer growth analysis. Major conclusion obtained on the model are as follows. The effect of H
O and O concentrations on ECP were successfully explained as the effects of oxide layer growth. Hysteresis of ECP under changes in water chemistry conditions were successfully explained with the model. Decreases in ECP due to neutron exposure were explained well by radiation-induced diffusion in the oxide layers.
Sakamaki, Keiko; Kataoka, Masaharu; Maeda, Toshikatsu; Iida, Yoshihisa; Kamoshida, Michio; Yamaguchi, Tetsuji; Tanaka, Tadao
Corrosion Engineering, Science and Technology, 49(6), p.450 - 454, 2014/09
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Corrosion experiments of a carbon steel plate embedded in bentonite mixture were conducted toverify our models assessing Eh evolution induced by corrosion of carbon steel overpack. Theexperimental results showed that the Eh decreased for the first 200 days and was subsequentlystabilised at around -450 mV; corrosion products were identified as magnetite and Fe waspresent mostly as divalent Fe within a 5 mm range from the carbon steel plate. Reactive transportmodelling was performed to assess the Eh evolution in the system using kinetic dissolution modelfor metallic iron and thermodynamic equilibrium models for other chemical reactions and closelyreproduced the experimental results. The models were verified only under the conditionsemployed in this study.
Taniguchi, Naoki; Suzuki, Hiroyuki; Kawasaki, Manabu; Naito, Morimasa; Kobayashi, Masato*; Takahashi, Rieko*; Asano, Hidekazu*
Corrosion Engineering, Science and Technology, 46(2), p.117 - 123, 2011/04
Times Cited Count：10 Percentile：48.33(Materials Science, Multidisciplinary)Carbon steel has been selected as one of the candidate materials for overpack for geological disposal of high-level radioactive waste in Japan. Corrosion of carbon steel is divided into two types; general corrosion and localized corrosion. In this study, propagation behaviors of general and localized corrosions (pitting corrosion and crevice corrosion) were investigated by immersion tests of carbon steel under aerobic condition. The results of the immersion tests showed that the growth rate of corrosion was strongly dependent on the environmental condition and steel type, but the upper limit of pitting factor (the ratio of the maximum corrosion depth and the average corrosion depth) was approximately determined by only average corrosion depth. Based on these experimental data and literature data, an empirical model that predicts the maximum corrosion depth of an overpack from average corrosion depth was developed by applying the extreme value statistical analysis using the Gumbel distribution function.
Kobayashi, Masato*; Yokoyama, Yutaka*; Takahashi, Rieko*; Asano, Hidekazu*; Taniguchi, Naoki; Naito, Morimasa
Corrosion Engineering, Science and Technology, 46(2), p.212 - 216, 2011/04
Times Cited Count：4 Percentile：27.90(Materials Science, Multidisciplinary)The corrosion behaviour of a carbon steel weld joint under anaerobic conditions was investigated to estimate the long-term integrity of the carbon steel overpack. The weld specimens in this study were produced using three welding methods: GTAW, GMAW and EBW. General corrosion was observed for each immersion specimen and the weld joint corrosion rate was the same as or less than that of the base metal. The hydrogen concentration absorbed during immersion testing was less than 2.48
10
mol kg[Fe]
(0.05 ppm) after three years, a value regarded as having little influence on hydrogen embrittlement. The susceptibility to hydrogen embrittlement was highest in the base metal, suggesting that there was little adverse effect on the weld joint from welding. The welded carbon steel overpack is assumed to maintain its resistance to corrosion as a disposal container for the expected lifetime under anaerobic underground conditions.
