Intergranular oxidation-embrittlement of Alloy 600 has been studied by surface analysis of fractured thin foils pre-exposed to hydrogenated steam at 400°C. The results are believed to be relevant to primary-water stress corrosion cracking in nuclear power plants. Earlier work had shown that preexposure to this environment caused several micrometers of intergranular failure during subsequent straining. This cracking had none of the characteristics of hydrogen embrittlement and could be due to oxidation of chromium and/or carbon at the grain boundaries, or to ingress of a monolayer of oxygen. New results show that an oxide phase of chromium does indeed penetrate but most of the cracking seems to be due to oxygen segregation. Sulfur was also found on the fractured boundaries.

Subject
Embrittlement, Foil, Materials, Fracture surfaces, Intergranular cracking, Specimen preparation, Sputter deposition, Oxygen, Grain boundary, Alloys, Stress corrosion cracking, Hydrogen, Oxidation
Keywords:
nickel-base alloys, nuclear, oxidation, stress corrosion cracking
© 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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