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川崎製鉄技報
KAWASAKI STEEL GIHO
Vol.17 (1985) No.3
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油性管用13Crマルテンサイト系ステンレス鋼の耐食性
Corrosion and Stress Corrosion Behavior of 13Cr Martensitic Stainless Steels in CO2-H2S-Cl- Environment

倉橋 速生(Hayao Kurahashi) 曽根 雄二(Yuji Sone) 和田 佳代子(Kayoko Wada) 中井 揚一(Yoichi Nakai)
要旨 :
0.2%C-13%Cr(C-Cr系)と0.02%C-13%Cr-3%Ni(Cr-Ni系)の2種の油井管用マルテンサイト系ステンレス鋼を用いてCO2環境,CO2+H2S環境での耐食性とCO2+H2S環境における耐SSC性を調べた。CO2環境では100℃以下できわめて良好な耐食性を示すが,高温高CO2分圧下ではその特長が消失する。CO2+H2S環境では全面腐食の程度は軽微であるが,隙間腐食感受性が著しく高くなる。またこの環境における耐SSC性は,不働態皮膜が安定に存在し得ない場合(C-Cr系がこれに相当)には低合金鋼より劣るが,安定な場合(Cr-Ni系がこれに相当)には,低合金と同様かそれ以上の耐SSC性を示す。
Synopsis :
Corrosion and stress corrosion behaviors of two types of 13Cr martensitic stainless steels, C-Cr type (0.2%-13%Cr) and Cr-Ni type (0.02%C-13%Cr-3%Ni), were investigated in CO2 and CO2+H2S environments. The 13Cr steels were resistant to CO2 corrosion at low partial pressure of CO2. High partial pressure of CO3 (30 atm), however, increases the corrosion rate of 13Cr steels at above 150℃. When a small amount of H2S is mixed into CO2 environment, crevice corrosion resistance is greatly decreased. Susceptibility to cracking was measured by the slow strain rate technique in CO2+H2S environment and changes in the corrosion potential were measured during the test. The C-Cr type steel reveals an active state in all these environments and its resistance to cracking is inferior to the low alloy steel used. The Cr-Ni type steel reveals a passive state, but is translated into an active state by straining. It is resistant to cracking.
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