The report reviews the available data on the embrittlement of duplex stainless steels under cathodic protection in sea water. Much of this data has previously been unpublished. The results show that while hydrogen enters duplex alloys at typical protection potentials (-1V SCE) the risk of failure is very low. The austenite phase tends to block cracks in the ferrite, and very high stresses are needed to produce fracture of the austenite or austenite-ferrite phase boundaries to enable crack propagation to occur. The smaller the grain size the more resistant duplex stainless steel is to embrittlement. The report also shows that currently used design stresses for duplex alloys are well below the stresses needed to produce failure. The service experiences with cathodically protected duplex are reviewed and the few failures explained. The report concludes that at normal protection potentials the risk of failure of duplex stainless steel due to hydrogen embrittlement is extremely low.

Subject
Embrittlement, Hydrogen embrittlement, Water, Materials, Stainless alloys, Cathodic protection, Stress cracking, Stress, Mechanical failure, Duplex stainless steel, Slow strain rate technique, Austenite, Hydrogen
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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