Micro structure is a key, yet often overlooked variable in micro-biologically influenced corrosion (MIC). A designed experiment was carried out to examine the effects of minor element content (Si, S, and Ce) on the susceptibility of low alloy steels to MIC in anaerobic aqueous systems. A two level, three factor full factorial experiment, using AISI 8630 as the master composition, was used to relate inclusion size, shape, chemical stability and spatial distribution to MIC susceptibility. Significant correlation between MIC susceptibility, measured as pit nucleation frequency and maximum pit size, and inclusion characteristics were found in these materials. Furthermore, significant differences in corrosion susceptibility for equivalent samples exposed to sterile and to biologically active solutions were found. For each heat studied, corrosion was significantly less severe in the sterile solution than in the biologically active solution. The results demonstrate a strong link between material microstructure and MIC and they suggest possible mitigation strategies based on microstructural design.

Subject
Pits, Sulfur, Materials, Cerium, Metal surfaces, Film formation, Heat, Pitting, Sulfides, Elements, Microorganisms, Microbiologically influenced corrosion, Inclusions
Keywords:
Low Alloy Steel, Inclusions, Microbiologically Influenced Corrosion, Microstructure, Analysis of Variance, Pitting
© 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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