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Stress corrosion cracking and electrochemistry of C−Mn steels in CO−CO2−H2O environments

Hassan Malik (International Islamic University, Faculty of Engineering, Department of Manufacturing and Materials Engineering, Kuala Lumpur, Malaysia)
Fahd Nawaz (GIK Institute of Engineering Sciences and Technology, Topi, NWFP, Pakistan)

Anti-Corrosion Methods and Materials

ISSN: 0003-5599

Article publication date: 1 October 2005

739

Abstract

Purpose

To discover if stress corrosion cracking (SCC) of C−Mn steel is possible at ambient pressure and temperature in a CO−CO2−H2O environment.

Design/methodology/approach

Approach involved electrochemical testing, slow strain rate testing (SSRT) and fractography. The chemistry within a crack or crevice during SCC differs from that of the bulk environment. To simulate this condition, a specimen was designed containing a steel plate, microelectrodes and artificial crevice. Electrochemical tests were performed to discover if conditions likely to cause SCC could be achieved. Slow strain rate tests and fractography was also carried out to support the electrochemical data.

Findings

Results indicated that CO can adsorb onto the metal and that localized corrosion occurred at defects in the adsorbed CO layer due to CO2, which led to the onset of SCC. Consequently, larger anodic and cathodic currents were measured with or without a crevice, when CO2 was in solution. Similar behaviour was observed on the microelectrodes. Regions of brittle fracture were discovered on the specimen surface after SSRT were conducted in a vapour phase environment. After such tests, the ductility of the steel was found to be impaired.

Practical implications

Practically the results could help to predict the potential range in which SCC may occur.

Originality/value

Paper is new because previous results were at high pressures. However, results indicate that SCC is a danger at atmospheric pressure. The paper is of value to people in the oil and gas industry.

Keywords

Citation

Malik, H. and Nawaz, F. (2005), "Stress corrosion cracking and electrochemistry of C−Mn steels in CO−CO2−H2O environments", Anti-Corrosion Methods and Materials, Vol. 52 No. 5, pp. 259-265. https://doi.org/10.1108/00035590510615749

Publisher

:

Emerald Group Publishing Limited

Copyright © 2005, Emerald Group Publishing Limited

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