The conditions for prevention and control of localized corrosion (pitting, crevice and SCC) of AISI 304, 316 and super γ 20Cr25Ni4.5Mo stainless steels in chloride containing waters have been defined by means of experimental electrode potential E vs NaCl concentration diagrams.

The existence has been established of a range of potentials within which localized corrosion propagation is stopped by a deactivation mechanism, while the free surface of the stainless steel remains passive; this type of protection is termed "controlled cathodic protection".

The effects of alloying elements, Ni, Cu, Mo and Cr on the behavior of localized corrosion have been exploited in particular with regard to protection conditions.

The validity of the diagrams has been checked by means of long term tests carried out under controlled conditions (in a laboratory loop and in natural sea water) on pre-corroded and non-precorroded specimens provided with crevice geometry.

The prevention of SCC has been studied by means of slow strain rate tests (SSRT) performed either at the free corrosion potential or at imposed potential.

Subject
Corrosion prevention, Anode potential, Cathodic protection, Cathodic potential, Repassivation potentials, Sodium chloride, Free corrosion potential, Corrosion propagation, Pitting, Localized corrosion, Stainless steel, Protection potential, Stress corrosion cracking
© 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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