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Tokita, Shun*; Kadoi, Kota*; Aoki, So; Inoue, Hiroshige*
Corrosion Science, 175, p.108867_1 - 108867_8, 2020/10
Times Cited Count：21 Percentile：80.42(Materials Science, Multidisciplinary)The purpose of this study is to evaluate the corrosion resistance of weld metal by electrochemical methods and discuss the relationship between microstructure and corrosion resistance. Intergranular and pitting corrosion resistances were measured using electrochemical potentiokinetic reactivation (EPR) test and pitting potential measurement respectively. The reactivation ratio and pitting potential corresponded to its chemical composition. The specimens containing more Cr and Mo showed higher resistance. In the EPR test, the dendrite core with a relatively low Cr content was corroded. In the pitting corrosion test, Nb carbide became the initiation site of pitting corrosion which propagated along the cell structure.
Sekio, Yoshihiro; Yamashita, Shinichiro; Sakaguchi, Norihito*; Shibayama, Tamaki*; Watanabe, Seiichi*; Tokita, Shun*; Fujii, Hiromichi*; Sato, Yutaka*; Kokawa, Hiroyuki*
no journal, ,
In order to improve ductility loss by helium embrittlement (or grain boundary embrittlement) induced under high temperature and neutron irradiation dose in nickel alloys which are expected to have high-temperature phase stability under non-irradiation, the grain boundary engineering was applied for NIMONIC PE16 to enhance the grain boundary strength. And, its high temperature tensile properties under non-irradiation were investigated as the first approach. As a result, the temperature dependence of the yield stress in the grain boundary engineered (GBE) PE16 was similar to that in NIMINIC PE16, but the yield stress was slightly lower and the uniform elongation was slightly higher at each temperature in GBE PE16 comparing to NIMINIC PE16. This would be caused by grain coarsening due to some heat treatments. If the gain size of GBE PE16 is optimized, tensile properties of GBE PE16 would be the same or more than that of NIMONIC PE16.
Yamashita, Shinichiro; Sekio, Yoshihiro; Sakaguchi, Norihito*; Shibayama, Tamaki*; Watanabe, Seiichi*; Tokita, Shun*; Fujii, Hiromichi*; Sato, Yutaka*; Kokawa, Hiroyuki*
no journal, ,
no abstracts in English
Tokita, Shun*; Kadoi, Kota*; Aoki, So; Inoue, Hiroshige*
no journal, ,
In this study, the objective was to estimate microstructure and corrosion resistance of weld metals of austenitic stainless steels to obtain characteristics of the weld metals and fundamental knowledge for improvement of its reliability. Electrochemical potentiokinetic reactivation (EPR) test and pitting potential measurement were carried out to estimate the corrosion resistance. In the EPR test, improvement of corrosion resistance at grain boundaries was confirmed in weld metal which included more Cr and Mo. On the other hand, Ni contents did not affect to EPR values. Etching microstructure along dendritic cell was observed in every EPR test. Weld metals which have a higher pitting index showed a higher pitting potential.
