Effects of Cu addition on hydrogen absorption and diffusion properties of 1470 MPa grade thin-walled steel tube under atmospheric corrosion

Shunsuke Toyoda, Hideto Kimura, Masayasu Nagoshi, Isamu Kage, Naotake Yoshihara, Jun'ichi Sakai

    研究成果: Article査読

    4 被引用数 (Scopus)

    抄録

    Hydrogen embrittlement is caused by the introduction of hydrogen into steel and is critical for high strength steels. To clarify the effects of Cu addition on hydrogen absorption and diffusion properties of steel under atmospheric condition, corrosion test was conducted on a 1 470 MPa grade thin-walled low carbon martensite steel tube. To this end, a martensite steel tube bearing 0.18% C, 0.4% Si, 1.5% Mn, 0.15% Cu, 0.01% Nb was prepared and compared with Cu free steel tube. As a result of EPMA mapping for the rust layer, Cu accumulated discretely on the rust/steel interface, especially in the bottom of pits of 0.15% Cu bearing steel tubes after the atmospheric corrosion test over 12 years. According to x-ray absorption near-edge structure (XANES) spectra, the valence of Cu in the rust layer was mainly +2 as Cu- (O, OH, SO4). The average and maximum diffusible hydrogen content level of 0.15% Cu bearing steel was lower than that of Cu free steel after the atmospheric corrosion test. The quantity of non-diffusible hydrogen was much higher than that of diffusible hydrogen. According to diffusion calculation results, hydrogen diffusion was so rapid that the long-term corrosion hysteresis seemed to have little influence on the diffusible hydrogen content. Furthermore, the short-term corrosion hysteresis may be the main determinant of diffusible hydrogen concentration. Having regard to the fact that the valance of Cu could also be 0 as reported by Shimizu et al., an inhibition mechanism from accumulated Cu on hydrogen-induced cracking was proposed. Eluted Cuy+ ions in the rust layer may precipitate as metallic Cu at the microscopic cathode during the corrosion test. As a result, the microscopic cathode becomes inactivated as an electrochemical reaction site for hydrogen. The Cu alternates between precipitates and Cu ions depending on the relative humidity, and the condensation and pH of the water in the rust layer.

    本文言語English
    ページ(範囲)1516-1523
    ページ数8
    ジャーナルISIJ International
    51
    9
    DOI
    出版ステータスPublished - 2011 9 15

    ASJC Scopus subject areas

    • 機械工学
    • 材料力学
    • 材料化学
    • 金属および合金

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