Premium
Corrosion mechanism of low‐alloy steel used for flexible pipe in vapor‐saturated H 2 S/CO 2 and H 2 S/CO 2 ‐saturated brine conditions
Author(s) -
Liu Zhenguang,
Gao Xiuhua,
Du Linxiu,
Li Jianping,
Zheng Chuanbo,
Wang Xiaonan
Publication year - 2018
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201810047
Subject(s) - corrosion , brine , microstructure , materials science , metallurgy , alloy , martensite , water vapor , chemistry , organic chemistry
Immersion experiment was used to elucidate the corrosion mechanism of low‐alloy pipeline steel exposed to vapor‐saturated H 2 S/CO 2 and H 2 S/CO 2 ‐saturated brine conditions in terms of microstructure, corrosion kinetics, corrosion products, surface/cross‐sectional morphology, and elemental distribution. The experimental results demonstrate that the microstructure of designed steel is tempered martensite, and the corrosion rate in H 2 S/CO 2 ‐saturated brine condition is larger than that in vapor‐saturated H 2 S/CO 2 condition. The main corrosion product in two corrosion conditions is FeS, which shows various crystal structures. The size of corrosion products formed in vapor‐saturated H 2 S/CO 2 condition is smaller than that of corrosion products formed in H 2 S/CO 2 ‐saturated brine condition, which contributes to the difference of water chemistry in two corrosion conditions. Cr‐rich compounds are primarily formed on the coupons surface of two corrosion conditions. The schematic models of corrosion mechanism in vapor‐saturated H 2 S/CO 2 condition and H 2 S/CO 2 ‐saturated brine condition are proposed based on experimental results.