Ennoblement of stainless steel by microbially deposited manganese oxides can cause pitting corrosion of the SS in natural waters at low chloride concentrations, leading to unexpected material failures. To study the effects of microbially deposited manganese oxides on pit initiation, we exposed 316L stainless steel to manganese oxidizing bacteria Leptothrix discophora under well-defined laboratory conditions. We then placed the ennobled coupons in a solution of low concentration sodium chloride until pitting initiated. The pits had different morphologies than those initiated by electrochemical polarization, hypothetically indicating a direct involvement of the bacteria in pit initiation.

Subject
Pits, Scanning electron microscopy, Steel surfaces, Atomic force microscopy, Reactors, Steel coupons, Sodium chloride, Corrosion initiation, Manganese, Sodium chloride solution, Bacteria, Corrosion coupons, Stainless steel
Keywords:
pitting, pitting of stainless steel, pit morphology, MIC, Leptothrix discophora, ennoblement
© 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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