Corrosion Protection of Galvanized Steel Sheet-Corrosion Investigation of Field Vehicle 912279

Three doors from three field vehicles made with one-side galvanized steel on the inside of the outer panels were investigated for perforation corrosion using microscopic and analytical methods after 8 or 10 years' field exposure in the snow-belt areas of North America. Perforation of these doors occurred within the lapped part of the door hems. Outer panel perforation began at the zinc layer on the inside surface of the outer panel at the lapped part and/or at the “bent part” of the outer panel of the door hems. Details of the micro corrosion behavior for the inside surface of the outer panel were made clear using EPMA analyses. The corrosion products on the inside surface of the outer panel were identified with X-ray diffraction.
Initially, zinc corrosion begins at the zinc coating layer of the upper side at the wax-free zone of the lapped part. Eventually zinc corrosion occurred beneath the wax layer as “Under-film corrosion”, proceeding gradually from the bottom to the top of the lapped part. The zinc is transformed into ZnO from the protective ZnCl2·4Zn(OH)2 initial product. Eventually, the steel substrate corrodes after the zinc coating loses its sacrificial corrosion protection. The steel is transformed into Fe3O4 and α, γ-FeOOH. It was found that this corrosion behavior was a common phenomena for the observed door hems.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Perforation Corrosion of Automobiles - Field Car and Laboratory Investigation


View Details


Corrosion Protection of Galvanized Steel Sheet - Corrosion Investigation of Field Vehicle and Its Laboratory Evaluation Methods


View Details


Corrosion Behavior of a Vehicle Submitted in Service in Subtropical Marine Environment of Okinawa Island for Eight Years


View Details