The effect of different material variables on Sulfide Stress Cracking (SSC) resistance of oil country tubular goods (OCTG) was analyzed. Several Cr-Mo-Nb microalloyed steels with different contents of Ti and B and different quenching and tempering conditions were used in order to obtain 110122 ksi yield strength. The SSC performances were evaluated by means of tensile tests and Double Cantilever Beam tests, NACE methods A and D, respectively.

Factors such as the microstructural features (e.g. the presence of upper and lower bainite, type and distribution of precipitates), the inclusion content and morphology were correlated to SSC initiation and propagation.

Initiation of SSC cracks is mainly related to the steel cleanliness, i.e. content of non-metallic inclusions and TiN particles, and hardness.

Propagation of SSC mainly depends on steel microstructure and strength. Materials having a refined austenite grain and tempered martensite microstructure (>95%) showed the best performance in sour conditions.

Improvement of SSC resistance was obtained through microalloying adjustment combined with multiple heat treatment process.

Subject
Tubular goods, Materials, Piping, Microstructure, Precipitates, Steel, Sulfide stress cracking, Hardness, Quenching and tempering, Grain, Austenite, Martensite, Inclusions
Keywords:
high strength low alloy steels (HSLA), sour environment, oil country tubular goods (OCTG), sulfide stress cracking (SSC), double cantilever beam (DCB), prior austenite grain size (PAGS)
© 2001 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).
2001
Association for Materials Protection and Performance (AMPP)
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