Permeation curves analysis allowed us to point out the formation of an iron sulfide layer which is very adherent to the steel surface.

The formation and then the evolution of this layer reduce in a very important way the hydrogen flow rate in the steel.

The formation rate of this layer, therefore its protection capacity, increases with the H2S concentration decreasing and pH increasing. Chlorides do not affect the curve forms in a significant way.

These different influences do not run for a very long time : after thirty hours, hydrogen flow rates seem to be unaffected by the sour aqueous medium.

General aspect of the permeation curves may be correlated to the H.I.C and S.S.C results. It appears that the influence of the corrosive medium is very important in the first thirty hours and this could explain that the nature of the corrosive medium is much more important in a H.I.C test (of total duration of 96 hours) than in a S.S.C test according to N.A.C.E standard TM 01-77 (of total duration of 720 hours).

Subject
Hydrogen concentration, Metal surfaces, Iron sulfides, Sodium chloride, Synthetic seawater, Pure water, Acidity, Permeation, Steel, Acetic acid, Chlorides, Hydrogen, Samples
© 1986 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).
1986
Association for Materials Protection and Performance (AMPP)
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