The electrochemical and stress corrosion cracking behavior of two pipeline steels commonly used in China were studied in a range of carbonate/bicarbonate solutions using potentiodynamic polarization techniques and the SCC tests. The influences of concentrations of carbonate, bicarbonate, oxygen and other compounds in solutions on their polarization characteristics as well as passivation behavior of pipeline steels were investigated. The SCC tests were conducted with bended tensile specimens and high concentration carbonate/bicarbonate solutions at 75°C. The sensitivity potentials were determined by fast and slow sweep rate curves and current-time curves. The typical corrosion stripes were observed on steel specimens after prolonged exposure to the solution used for the SCC tests at the sensitivity potentials that were believed as a premonitory of SCC. Two different surface films on the steels were found after SCC tests depending on the control potentials. Their morphology and composition were also analyzed using SEM and X-ray energy dispersion.

Subject
Electric current, Films, Steel surfaces, Anode potential, Pipelines, Polarization curves, Steel, Carbonate stress corrosion cracking, Electrochemical potential, Corrosion potential, Stress corrosion cracking, Electrode potential, Oxidation
Keywords:
pipeline steels, SCC, carbonate-bicarbonate solution, polarization curves, sensitivity potentials
© 2004 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2004
Association for Materials Protection and Performance (AMPP)
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