Conventional 0.2C-13Cr martensitic steel has a higher SSC susceptibility in NACE TM-01-77 solution (0.5% acetic acid + 5% NaCl, 25°C(75°F), saturated with 0.1MPa (15psi) H2S) and in the modified NACE solution (0.5% acetic acid + 5% NaCl, 25°C(75°F), 0.01MPa (1.5psi) H2S) than low alloy steel. This is due to a higher hydrogen content (C0) in 13Cr steel although the threshold hydrogen content (Cth) for SSC is almost the same as that of low alloy steel with same strength. The reason why 13Cr steel has a higher C0 is because it has a smaller apparent diffusion coefficient (D) of hydrogen in steel.

In addition, it was found that 13Cr steel becomes less susceptible to SSC in the modified NACE solution with 0.01MPa(1.5psi) H2S than in the brine containing H2S of the same partial pressure and CO2. It was concluded that the stress concentration caused by pitting would play an important role for the SSC of 13Cr steel in the CO2 - H2S condition, because SSC occurred at the bottom of pitting in the above condition. On the other hand, general corrosion was dominant and no deep pitting occurred in the modified NACE solution. Therefore, it was suggested that the low pH solution containing acetic acid such as the standard NACE solution was inappropriate for the evaluation of 13Cr steel.

Subject
Hydrogen embrittlement, Hydrogen permeation, Hydrogen content, Tensile tests, Partial pressures, Sodium chloride solution, Steel, Brines, Pitting, Sulfide stress cracking, Hydrogen, Types of corrosion, Low alloy steel
Keywords:
13Cr martensitic steel, sulfide stress cracking (SSC), NACE TM-01-77 solution, hydrogen embrittlement, pitting, general corrosion, threshold hydrogen content (Cth), hydrogen content in steel (C0)
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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