Very high stress corrosion cracking susceptibility of Types 304 and 310 austenitic stainless steels (SS) occurred at 60 °C upon exposure to a concentrated FeCl2-CrCl3- NiCl2 solutions (abbreviated as MClz), which is representative of the anolyte formed in occluded regions during localized corrosion in Cl− solutions. Stress corrosion cracking of 304 SS occurred in the absence of applied stress for tests between 60 and 200 °C. Crack initiation in MClz occurred only under conditions of active corrosion, and was accompanied by significant hydrogen absorption. Additional studies evaluated solution acidity and corrosion kinetics in concentrated MClz solutions. Test results support a hydrogen-assisted active corrosion model for both crack initiation and crack growth. Obvious challenges to such a model have been presented and then addressed in relation to current and published test results.

Subject
Crack growth, Foil, Active corrosion, Hydrogen concentration, Corrosion rate, Crack initiation, Solubility, Corrosion reactions, Corrosion cracking, Acidity, Corrosion modeling, Film formation, Stress corrosion cracking
Keywords:
austenitic stainless steels, stress corrosion cracking, anolyte, ferrous chloride, chromic chloride, absorbed hydrogen
© 2001 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).
2001
Association for Materials Protection and Performance (AMPP)
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