Electrochemical mechanism of stress corrosion cracking of API X70 pipeline steel under different AC frequencies. (20th May 2018)

• Record Type: Journal Article
• Authors: Liu, Q.; Wu, W.; Pan, Y.; Liu, Z.Y.; Zhou, X.C.; Li, X.G.
• Is Part Of: Construction & building materials. Volume 171(2018)
• Page Start: 622
• Page End: 633
• Publication Date: 2018-05-20
• Subjects: Pipeline steel -- Alternating current frequency -- Non-steady electrochemical process (NEP) -- Stress corrosion cracking; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.03.209
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: A fundamental understanding of SCC mechanism under AC interference at different frequencies is investigated. The processes of Faraday and non-Faraday derived from the AC are discussed in detailed. Catalytic effect of various AC frequencies on SCC behavior is proposed. Abstract: Electrochemical and SCC behaviour of X70 pipeline steel samples were investigated under various AC frequencies to elucidate the mechanistic aspects of the alternating current (AC)-assisted stress corrosion cracking (SCC) of pipeline steels in simulated seawater solutions. Results indicate that AC serves as a critical influencing factor on SCC of X70 pipeline steel by accelerating the mass transfer and in-situ-O2 -generation, and hydrogen evolution due to the non-Faraday and Faraday potential of AC, respectively. The electrochemical reactions show a maximum rate around 30 Hz, which is attributed to the periodic effect of AC frequency on the different processes; a similar trend is observed in SCC behaviour with increase in AC frequency. AC catalyses both the anodic dissolution (AD) and hydrogen evolution reactions, and greatly increases the SCC susceptibility resulting from the combined effect of increased AD and hydrogen embrittlement (HE) on the SCC process.