The stress corrosion cracking (SCC) behavior of duplex stainless steel (DSS) in H2S-Cl- environment has been discussed for a long time. However, the high H2S-CO2 pressure and the high Cl- content can coordinate to cause severe pitting or SCC of DSS. There has been limited information on the mechanism of SCC of DSS under high H2S-CO2 pressure with high Cl- content. In this paper, SCC of UNS S31803 DSS was investigated under different H2S-CO2 pressures (300 kPa H2S + 200 kPa CO2, 600 kPa H2S + 400 kPa CO2, 900 kPa H2S + 600 kPa CO2) with 150,000 ppm Cl- at 60 ⁰C. Four-point bend beam test method and scanning electron microscopy analysis were combined to investigate the SCC mechanism of DSS. The effect of high H2S-CO2 pressure on SCC mechanism was discussed. The results indicated that under lower H2S-CO2 pressure, cracks initiated and propagated at pitting areas which were caused by anodic dissolution mechanism. Under 900 kPa H2S + 600 kPa CO2, except the pitting assisted cracking areas, there also existed some hydrogen stress cracking at crack terminals. The higher H2S-CO2 pressure can facilitate both hydrogen embrittlement and anodic dissolution.

Subject
Scanning electron microscopy, Corrosion rate, Passive films, Crack propagation, Corrosion cracking, Stress cracking, Corrosion products, Anodic dissolution, Pressure, Steel, Localized corrosion, Stainless steel, Stress corrosion cracking
Keywords:
stress corrosion cracking (SCC), pitting, duplex stainless steel (DSS), H2S-CO2, Four-point Bend Beam test
© 2013 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).
2013
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.