On-Vehicle Cosmetic Corrosion Evaluations of Coated and Cold Rolled Steel Sheet

Cosmetic corrosion resistance of coated and cold rolled steel sheet products is being determined by use of test coupons (paint panels) mounted on full-size pickup trucks operating in the severe corrosive environments of Montreal, Quebec and St. John's, Newfoundland, Canada, Ten standard materials from the joint AISI/SAE corrosion test development program, including hot-dip galvanized, galvannealed, electroplated zinc and zinc-nickel alloy-coated, as well as phosphated and unphosphated cold rolled steel have been under evaluation for five years.

The results of these evaluations are described in terms of resistance to paint undercutting (creepback) and red rust staining at scratches (scribes) through the paint film to the steel substrate. The effects of horizontal and vertical test coupon orientations are considered. Performance of the materials in this evaluation provides an excellent standard of real-world behavior against which the reliability of accelerated tests can be determined.