Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Volume 69 , Issue 9
Showing 1-4 articles out of 4 articles from the selected issue
Commentary
Technical Review
Research Paper
  • Makoto Kawamori, Junichiro Kinugasa, Yuko Fukuta, Masaki Shimamoto, To ...
    2020 Volume 69 Issue 9 Pages 237-245
    Published: September 10, 2020
    Released: March 04, 2021
    JOURNALS RESTRICTED ACCESS

    The effect of Ta addition on the pitting corrosion resistance of duplex stainless steels was investigated in both cases without and with deoxidization/desulfurization by addition of Al and Ca. The pitting corrosion resistance was improved by addition of Ta with two proposed mechanisms. For steels without Al and Ca, the MnS inclusions which act as initiation sites of the pitting corrosion are modified to the electrochemically-stable (Ta,Mn) oxysulfides. For steels with Al and Ca, the pitting initiation sites (CaS and (Al,Ca) oxides) are coated with the stable Ta-containing nitrides resulting in the suppression of pitting corrosion propagation.

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  • Kyohei Otani, Takashi Tsukada, Fumiyoshi Ueno, Chiaki Kato
    2020 Volume 69 Issue 9 Pages 246-252
    Published: September 10, 2020
    Released: March 04, 2021
    JOURNALS RESTRICTED ACCESS

    The purpose of this study was to investigate the effect of artificial seawater components on the corrosion rate of carbon steel under air/solution alternating condition, and to clarify the corrosion mechanism of carbon steel that changes with artificial seawater concentration. Mass measurements showed that the corrosion rate of carbon steel in the alternating condition accelerates with increasing concentration in the concentration region between deionized water to 200 times diluted artificial seawater(ASW), and the corrosion rate decreases with increasing concentration in the concentration region between 20 times diluted ASW to undiluted ASW. It can be considered that the reason why the carbon steel corrosion was suppressed in highly concentrated artificial seawater would Mg ions and Ca ions in the artificial seawater precipitate and cover on the surface due to the increase in pH near the surface by oxygen reduction reaction.

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