Effect of Strength and Microstructure on Stress Corrosion Cracking Behavior and Mechanism of X80 Pipeline Steel in High pH Carbonate/Bicarbonate Solution
- 459 Downloads
The stress corrosion cracking (SCC) behaviors and mechanisms of X80 pipeline steels with different strength and microstructure in high pH carbonate/bicarbonate solution were investigated by slow strain rate testing and electrochemical test. The results showed that the cracking mode of low strength X80 steel composed of bulky polygonal ferrite and granular bainite in high pH solution was intergranular (IGSCC), and the SCC mechanism was anodic dissolution (AD). While the mixed cracking mode of high strength X80 steel consisted of fine acicular ferrite and granular bainite was intergranular (IGSCC) in the early stage, and transgranular (TGSCC) in the later stage. The decrease of pH value of crack tip was probably the key reason for the occurrence of TGSCC. The SCC mechanism may be a mixed mode of AD and hydrogen embrittlement (HE), and the HE mechanism may play a significant role in the deep crack propagation at the later stage. The cracking modes and SCC mechanisms of the two X80 steels were associated with its microstructure and strength.
KeywordsX80 pipeline steel stress corrosion cracking strength and microstructure hydrogen embrittlement
The authors are grateful for the financial support from the National Natural Science Foundation of China (Registration No. 51371036 and No. 51131001).
- 9.T.R. Jack, B. Erno, K. Krist, and R. Fessler, Generation of Near Neutral pH and High pH SCC Environments on Buried Pipelines, Proceedings of Corrosion 2000. Paper 00362. NACE International, Houston, TX, 2000 (Corrosion 2000. Paper No. 363, NACE, Houston, 2000)Google Scholar
- 26.J.Q. Wang, A. Atrens, and D.R.G. Mitchell, Grain Boundary Characterization of X42 Pipeline Steel in Relation to IGSCC, Proceedings of Corrosion 2001. Paper 01210. NACE International, Houston, TX, 2001 (Corrosion 2001. Paper No. 210, NACE, Houston, 2001)Google Scholar
- 27.M.J. Danielson, R.H. Jones, and P. Dusek, Effect of Microstructure and Microchemistry on the SCC Behavior of Archival and Modern Pipeline Steels in A High pH Environment, Proceedings of Corrosion 2001. Paper 01211. NACE International, Houston, TX, 2001 (Corrosion 2001. Paper No. 211, NACE, Houston, 2001)Google Scholar
- 28.P. Liang, Corrosion Behavior and Mechanism of X80 Pipeline Steel in Ku’erle Soil Simulated Solution. PhD Thesis, University of Science and Technology Beijing 2008 [in Chinese]Google Scholar
- 30.Chinese National Standard for Stress Corrosion Cracking Tests, GB T 15970, 2007Google Scholar
- 37.W.L. Zheng, Effect of Strength of Steels on the Susceptibility to Stress Corrosion Cracking, J. Chin. Soc. Corros. Prot., 1984, 4, p 287–294 ((in Chinese))Google Scholar
- 42.H. Guo, G.F. Li, X. Cai, and W. Yang, Stress Corrosion Cracking Behavior of X70 Pipeline Steel in Near-Neutral pH Solutions at Different Temperatures, Acta Metall. Sin., 2004, 40, p 967–971 ((in Chinese))Google Scholar