In recent years, increasing attention has been given to the need to develop an accelerated laboratory test method(s) for cosmetic corrosion of painted panels that realistically simulate in-service exposure1-3 . Much of that work has focused on steel substrates. The purpose of this research is to compare the corrosion performance of painted aluminum and steel sheet as determined from various laboratory methods and in-service exposure, and to develop a realistic accelerated test method for evaluation of the cosmetic corrosion of painted aluminum. Several aluminum sheet products from the 2xxx, 5xxx, and 6xxx alloy series have been tested. The steel substrates are similar to those used in other programs1-3 . The test methods chosen represent a cross-section of methods common to the automotive and aluminum industries for evaluation of painted sheet metal products. The results indicate that there is considerable difference in the relative correlation of various test methods to in-service exposure. In addition, there is considerable difference in the relative magnitudes and morphologies of corrosion, and occasionally in the relative rankings, as a function of test method. The influence of alloy composition and zinc phosphate coating weight are also discussed.

Subject
Test methods, Coatings, Correlation, Materials performance, Aluminum, Steel substrates, Corrosion attacks, Phosphates, Salt spray corrosion testing, Steel, Highways, Aluminum alloys, Alloys
Keywords:
aluminum, steel, filiform corrosion, cosmetic corrosion, automotive, test development, zinc phosphate coatings
© 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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