A review of calculation methods for atmospheric corrosion ratings of high-strength, low-alloy weathering steels, such as ASTM A242 and A588, shows that a wide range of "rating numbers" relative to carbon steel (or copper-bearing steel) can be obtained from the same data set by using different methods. Therefore, such rating numbers cannot be used for comparison purposes unless the exact method of calculation is specified. (ASTM specifications do not specify the method.) More importantly, however, an analysis of the rating numbers as compared to actual corrosion losses in various environments leads to the conclulusion that the rating numbers have little practical significance. Moreover, misinterpretation of the rating numbers can lead to erroneous conclusions with respect to the durability of weathering steels in a given environment.

It is recommended, therefore, that the use of corrosion rating numbers for weathering steels be phased out, and that a more meaningful method of rating the performance of these steels be sought.

Subject
Atmospheric corrosion, Materials, Slopes, Thickness loss, Linear regression, Corrosion losses, Weathering, Steel, Corrosion data, Carbon steel, Carbon, Corrosion resistance, Copper
© 1987 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).
1987
Association for Materials Protection and Performance (AMPP)
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