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Evaluation of the Corrosion Rate of Zn Coated Steel Sheets for Automotive Body Use
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Abstract
The corrosion mechanism of zinc coated steel sheets in automotive bodies was studied in field vehicle tests and several types of accelerated tests. Perforation corrosion starts in unpainted areas of lapped parts, and proceeds in the following steps: i) galvanic protection by the Zn coating, ii) protection by corrosion products, and iii) corrosion of the steel substrate and perforation. Although the corrosion processes were the same in all the cases tested, the corrosion rate depended significantly on the environment, such as atmospheric exposure conditions and the part of the automotive body. In accelerated corrosion environments, Zn coating is largely ineffective against perforation corrosion because galvanic protection and protection by corrosion products cannot be maintained over the long term. Conversely, coating is highly effective under actual atmospheric conditions which produce slow corrosion rates because galvanic protection and protection by corrosion products continue to protect the steel substrate over an extended period. Accelerated tests may be an accurate predictor of corrosion in cold rolled steel, but may not be representative of corrosion in coated products. On the other hand, cold rolled steel can be used to extrapolate the rate of corrosion in coated products. Therefore to evaluate the effects of Zn coatings quantitatively, the authors suggested an index of for corrosion resistance relative to cold rolled steel sheets under each atmospheric conditions. It is considered possible to estimate actual perforation corrosion life by using this index.
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Authors
Citation
Kurokawa, S., Uchida, M., Kato, C., Mochizuki, K. et al., "Evaluation of the Corrosion Rate of Zn Coated Steel Sheets for Automotive Body Use," SAE Technical Paper 971003, 1997, https://doi.org/10.4271/971003.Also In
References
- Hayashi K. “Under-film Corrosion of Precoated Steel Sheets for Automobiles” J. of The Adhesion Soc. of Japan 26 5 1990 194 201
- Hayashi K. Ito Y. Kato C. Miyoshi Y. “Under-film Corrosion Behavior of Zinc Alloy Coated Steel Sheets for Automobiles” Testu-to-Hagane 76 8 1990 115 122
- Miyoshi Y. to Y.I Soreide L.E. Davidson D.D “Corrosion Protection Function of Zinc Coating on Steel Sheet, as Revealed by the Investigation of Field Cars and Laboratory Test” 2nd International Conference on Zn and Zinc Alloy Coated Steel Sheet GALVATECH '92 528 534
- Bryant A. W. et al. “U.S. Auto motive Corrosion Trends at 5&6 years” SAE Technical Paper Series 892578 1989
- Kurokawa S. Ban T. Yamato K. Ichida T. “A Study on Cosmetic and Perforation Corrosion Test for Automotive Steel Sheets” Testu-to-Hagane 72 8 1986 223 230
- Kurokawa S. Yamato K. Ichida T. “A Study on Cosmetic and Perforation Corrosion Test Procedures for Automotive Steel Sheets” paper no.396, The NACE Annual Conference and Corrosion Show Cincinnati, Ohio, USA
- Wakano S. Nishimura M. “Corrosion Resistance of Several Coated Steels through Simulation Tests” Sumitomo Metals 41 2 1989 11 18
- Uchida M. et al. “Corrosion Behavior of a Vehicle Submitted in Service in Subtropical Marine Environment of Okinawa Island for Eight Years” SAE Technical Paper Series 960021 1996
- Misawa T. “Research Status and Unsolved Problems in Rusting of Iron and Steel” Corrosion Engineering 32 11 1983 657 667
- Johansson E. Gullman J. “Corrosion Study of Carbon Steel and Zinc-Comparison Between Field Exposure and Accelerated Tests” ASTM Spec Tech Publ (Am Soc Test Mater) No. 1239 240 256 1995