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A cooperative effort by the North American automotive and steel industries is being spear-headed by the Corrosion Task Force of the American Iron and Steel Institute (AISI). This work is aimed at development of an improved laboratory accelerated test for ranking the cosmetic corrosion resistance of automotive steel sheet products. In this paper, we review the AISI program including its objective, approach, and relationships with other organizations, particularly with SAE's Automotive Corrosion and Prevention Committee. Results of four cyclic laboratory tests considered by the Task Force are compared to those of two-year on-vehicle tests conducted in the severely corrosive environments of St. John's, Newfound-land and Montreal, Quebec. Statistical methods are used to depict the material rankings of each test, and to compare the rankings between the laboratory and field tests.

Cathodic electrocoat primers (cathodic e-coat) have been widely adopted by the automobile industry. One drawback to these coatings is that they display a tendency for formation of crater-like features when applied to zinc-rich surfaces under typical automotive application conditions. Our studies show that cratering susceptibility is an inherent property of zinc and that the craters result from localized dielectric breakdown of the e-coat film during deposition. Energy from the electric discharges displaces the e-coat at the discharge sites and locally cures the adjacent e-coat. During cure-baking, the locally cured e-coat does not re-flow to fill the voids created by the discharges, resulting in crater-like features in the cured e-coat film.