In order to investigate the perforation corrosion resistance of Zn-Ni alloy electroplated steel sheets in actual usage for automobiles, a pair of rear doors which were made from Zn-Ni alloy electroplated steel sheets and cold-rolled steel sheets were assembled for an automobile running test in Okinawa for 5 years. After 2.5 years, perforation corrosion penetrated an outer rear door of 0.6mm thick cold-rolled steel sheet. After 5 years, doors were deassembled and perforation corrosion was investigated. In the Zn-Ni coated door, corrosion occurred only at the hem flanges and the maximum corrosion depth was 0.05 mm. Granted that the Zn-Ni coating entirely loses its protection of steel and the perforation corrosion rate, hereafter, is the same as that of cold-rolled steel, it is assumed that the perforation corrosion should, eventually, penetrate a 0.6mm thick Zn-Ni coated outer panel in 7 years.

Subject
Zinc nickel coatings, Zinc rich coatings, Materials, Corrosion resistant alloys, Perforation, Flanges, Corrosion products, Steel sheet, Zinc oxide, Steel, Rust, Automotive, Corrosion resistance
Keywords:
Zn-Ni alloy electroplated steel sheet, corrosion resistance, automotive steel sheet, perforation corrosion, field test
© 1991 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).
1991
Association for Materials Protection and Performance (AMPP)
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