The effects of the chromium depleted mill finished surface on the localized corrosion resistance of alloy 825 were investigated. Tests conducted in solutions simulating the groundwater at Yucca Mountain with a higher concentration of chloride indicated that the breakdown and repassivation potentials for the mill finished surfaces were more active than those for polished surfaces. Potentiodynamic polarization tests indicated that pits can be initiated on the chromium depleted surface at potentials of 220 mVSCE in a solution containing 1,000 ppm chloride at 95°C. Potentiostatic tests identified a similar pit initiation potential for the mill finished surface. However, under longer term potentiostatic tests, a higher potential of 300 mVSCE was needed to sustain stable pit growth beyond the chromium depleted layer. An increase in the surface roughness decreased the localized corrosion resistance of the material.

Subject
Surface finishing, Pits, Materials, Composition, Metal surfaces, Chromium, Repassivation potentials, Containment, Corrosion initiation, Surface layers, Electric potential, Pitting, Alloys
Keywords:
alloy 825, pit, localized corrosion, waste containers, chloride, groundwater, high-level waste
© 1994 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).
1994
Association for Materials Protection and Performance (AMPP)
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