Lap-joint corrosion of automotive coated materials in chloride media. Part1 - Electrogalvanized steel

Lap-joint corrosion has been studied by several authors. However, the mecha nisms involved in this type of corrosion, in the specific case of new paint ing substrates for the automotive industry, are not at all clear. The main purpose of this work is to study lap-joint corrosion in modern automotive p ainting substrates, namely electrogalvanized steel, galvanneal and electrog alvanized/galvanneal assemblies. In this first part of the work, electrogal vanized steel is studied using special specimens with spot-welded lap-joint s, before and after salt-spray exposure. Special lap-joint spacements and p ositions were involved. The corrosion mechanisms proposed were based on the results obtained by visual observations, scanning electron microscopy (SEM ) associated with X-ray energy dispersive spectrometry (EDS), X-ray diffrac tion (XRD), Auger spectroscopy (AES) and X-ray photoelectron spectroscopy ( XPS). (C) 2000 Elsevier Science S.A. All rights reserved.