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International Journal of Corrosion
Volume 2012, Article ID 414156, 13 pages
http://dx.doi.org/10.1155/2012/414156
Research Article

Environmental and Material Influences on the Stress-Corrosion Cracking of Steel in H2O–CO–CO2 Solutions

School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa

Received 14 March 2012; Revised 18 April 2012; Accepted 26 April 2012

Academic Editor: Rokuro Nishimura

Copyright © 2012 J. W. van der Merwe. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The stress-corrosion cracking of A516 pressure vessel steel was investigated by the use of slow strain-rate tests. The orientation of samples to the rolling direction was investigated, and it was found that samples machined longitudinal to the rolling direction showed a slightly increased sensitivity to stress corrosion. The temperature variation showed that for different gas mixtures, the maximum sensitivity to stress corrosion was in the region of 45° to 55°C for the 25% CO gas mixture, whereas with higher CO concentrations, this temperature region of maximum sensitivity moved to higher temperatures. Surface finish showed a slight increase in sensitivity to cracking with increased surface roughness. The most significant increase was found with increased total gas pressures and when samples have been exposed to the environment for an extended period. This was as a result of the inhibition of the corrosion reaction by the passivation of the carbon monoxide, which is a time-dependent process.