The corrosion resistance of a martensitic stainless steel was investigated in a CO2 environment containing a small amount of H2S. A 13Cr-5Ni-2Mo steel showed a highly-improved corrosion resistance to both sulfide stress cracking(SSC) at ambient temperature and localized corrosion at elevated temperature compared with conventional 13Cr steel(AISI 420). Effects of environmental factors such as H2S partial pressure, Cl-, pH and temperature on those corrosions were studied using constant-strain method, hydrogen-permeation technique and electrochemical method. The limitations of H2S partial pressure and temperature to sustain the corrosion resistance against SSC and localized corrosion were 0.001 to 0.003MPa(0.15 to 0.45psi) H2S and 150C, respectively. However, the H2S threshold pressure changed depending on pH and Cl- ion concentration. For example, the new 13Cr-5Ni-2Mo steel did not suffer SSC even at 0.01MPa(1.5psi) H2S when Cl- ion concentration was 100ppm or below.

Subject
Materials, Manufacturing, Corrosion rate, Stress cracking, Partial pressures, Ion concentrations, Steel, Pitting, Corrosion resistance, Localized corrosion, Sulfide stress cracking, Hydrogen, Martensitic steel
Keywords:
martensitic stainless steel, sulfide stress cracking(SSC), pitting corrosion, crevice corrosion, carbon dioxide, hydrogen sulfide, 13% chromium, high strength, oil country tubular goods, nickel
© 1992 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).
1992
Association for Materials Protection and Performance (AMPP)
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