Title: Corrosion Protection of Galvanized Steel Sheet - Corrosion Investigation of Field Vehicle and Its Laboratory Evaluation Methods
text: For the accumulation of knowledge of perforation corrosion, three doors of three field vehicles made with one-side galvanized steel on the inside of the outer panels were investigated with some microscopic and analytical methods after 8 or 10 years’ field running in the snow-belt areas of North America. For these doors, perforations were found within the lapped part of the door hems. Outer panel perforation began as zinc layer corrosion of the inside surface of the outer panel at the lapped part and/or as “bent part” corrosion of the outer panel at the door hem. The inside of the outer panel lightly corroded at the open part in spite of the lack of primer on the inside surfaces of the outer and inner panels. The corrosion behavior of a lapped panel specimen test was studied and compared with that of investigated door hem corrosion. In the case of these doors, the test provided a result having a fairly good agreement with the field vehicle doors’ behavior.