In this study a total of fourteen alloys from the groups of martensitic (MSS), precipitation hardened (PHSS), and duplex (DSS) stainless steels were exposed to simulated petroleum production environments containing H2S, CO2, chloride and bicarbonate to produce a range of conditions. The particular focus of this study was the documentation of the effects of environmental and metallurgical variables on the resistance to stress corrosion cracking (SCC) and sulfide stress cracking (SSC) of these materials. Slow strain tests were also conducted in order to obtain additional information.

The SCC/SSC behavior of stainless steel alloys was observed to be significantly different for conditions resulting in pH < 4.0 than for those given pH > 4.0. Buffered environments producing pH greater than 4.0 tended to be considerably less severe from the standpoint of cracking. In buffered solutions, the environmental limits for MSS and PHSS materials were 10,000 ppm Cl− and 6.9 kPa (1.0 psia) H2S. The safe use limits for coldworked DSS materials were 100,000 ppm Cl− and 6.9 kPa (1.0 psia) H2S under buffered conditions. The annealed DSS were not susceptible for SCC at 100,000 ppm Cl− and up to 68.9 kPa (10 psia) H2S under unbuffered conditions based on 30 day exposure data. The pH of the test environments had less of an effect with increasing alloy content.

The tested alloys exhibited the general trend of increasing general corrosion with increasing temperature. However, the MSS alloys and some of the DSS alloys exhibited increased susceptibility to localized corrosion at 93 C (200 F) than at 204 C (400 F) due to the transitions from passive to active behavior or from varying passive states (i.e. oxide to sulfide).

Subject
Materials, Stainless alloys, Autoclaves, Sour environments, Corrosion cracking, Test environments, Corrosion data, Localized corrosion, Sulfide stress cracking, Alloys, Stress corrosion cracking, Types of corrosion, Chloride stress corrosion cracking
Keywords:
martensitic, precipitation hardened, duplex, stress corrosion cracking, sulfide stress cracking, slow strain rate, localized corrosion
© 1997 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).
1997
Association for Materials Protection and Performance (AMPP)
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