Effect of microstructural aspects in the heat-affected zone of high strength pipeline steels on the stress corrosion cracking mechanism: Part I. In acidic soil environment

• DOI: 10.1016/j.corsci.2019.108167
• Publication Date: 2019-08-15T09:58:14Z
• Authors: Xueda Li; Jiahang Liu; Jianbo Sun; Xueqiang Lin; Chunyu Li; Ning Cao
• Keywords: 02 engineering and technology; 15. Life on land; 0210 nano-technology

Abstract Microstructures consisted of bainite/ferrite matrix and varied distribution of martensite-austenite (M-A) constituent in the heat-affected zone of X100 pipeline steel were simulated, and their effect on stress corrosion cracking (SCC) mechanism in acidic soil environment were investigated. The results showed that microstructure characteristic, especially distribution of M-A constituent, had large effect on SCC sensitivity. Micro-galvanic effect, stress/strain concentration and hydrogen involvement facilitated formation of microvoids at M-A/matrix interface, which could promote initiation and propagation of SCC microcracks through microvoids coalescence. SCC microcracks also preferred propagating along upper bainite laths whereas acicular ferrite and quasi-polygonal ferrite could inhibit the crack propagation.