Prephosphating treatments have been found to improve several performance characteristics of zinc coated steel strip, namely its forming properties in automotive stamping plants and its corrosion resistance during storage, transport and processing prior to painting. An investigation of the benefits of prephosphating of galvannealed coatings on steel strip is now being conducted. The galvannealing heat treatment process converts the unalloyed zinc coating to a fully alloyed iron-zinc layer and improves paint adherance, spot weldability and corrosion resistance compared to the unalloyed coating. A description is given of a research program which is determining the performance of galvannealed strip, with special emphasis on paintability and cyclic corrosion resistance of prephosphated galvannealed strip subjected to simulated automotive stamping operations.

Subject
Scanning electron microscopy, Test methods, Zinc rich coatings, Steel surfaces, Coatings, Substrate surfaces, Steel sheet, Phosphates, Weldability, Steel, Corrosion resistance, Zinc, Oil
Keywords:
prephosphating, zinc coated, galvannealed steel, intermetallic phases, formability, weldability, paintability, corrosion resistance, trication phosphate, automotive applications
© 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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