Hydrogen sulfide contained in crude oil and natural gas causes hydrogen related problems such as hydrogen induced cracking (HIC) and sulfide stress cracking (SSC) of pipeline steels. In particular, HIC is a more serious problem because it occurs without applied stress. To improve HIC resistance, addition of proper alloying elements, high cleanness and Ca treatment during steel making processes are required. However, the effects of metallurgical factors on HIC are not well understood to improve HIC resistance of pipeline steels.

In this study, HIC resistance of two high strength steel plates was evaluated by using NACE TM0284-02 methods. After the tests, HIC resistance was measured in terms of crack area ratio (CAR) using ultrasonic detector. Fracture behavior of HIC was investigated by observing fractured surfaces using optical microscopy (OM) and scanning electron microscopy (SEM). HIC property was discussed in terms of metallurgical parameters such as primary microstructure, second phases and inclusions. Results showed that cracks nucleated in the steels are affected not only by the presence of inclusions but also by the microstructure surrounding it. In this study, the effect of various metallurgical factors on nucleation and propagation of HIC was discussed in detail.

Subject
Scanning electron microscopy, Hydrogen induced cracking, Oxides, Microstructure, Diffusible hydrogen, Nucleation, Pipelines, Crack propagation, Clusters, Steel, Hydrophobic interaction chromatography, Hydrogen, Inclusions
Keywords:
hydrogen induced cracking, pipeline steel, microstructure, inclusion, second phase
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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