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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Phase structure of galvanized zinc on sheet steel
Q. Dear Sir,
I am really want to know the structure of Zinc sheet (tole). If can, you advise me where I can get this information! And also you can tell me the basics of tole (formula, the thickness of each level!)
Thanks a lot and warm regards!
Jackie ThuStudent - Dong Nai, Viet Nam
2003
A. Do you mean zinc-coated sheet steel? Formulas and thicknesses of layers make sense for galvanized steel produced by hot-dipping in molten zinc. The liquid zinc alloys with the steel (iron) to form the phases of the Fe-Zn phase diagram: Fe (containing up to 6.3 wt% Zn at its surface), Gamma (20.5-28 wt% Fe), delta (7-10% Fe), zeta-FeZn13 (6-6.2% Fe) and Zn.
The Gamma layer comprises about 1% of the coating thickness, delta about 5%, zeta about 40%, and the Zn surface layer being the remainder. There is some intermixing of the zeta and zinc phases.
A common galvanized coating specification (U. S. and EN ISO 1461) is 2 oz/square foot (600 g/sq.meter) by weight, or 0.0033 inch (85 microns) by thickness.
The American Galvanizers Association publication "Zinc Coatings" shows cross-sectional microstructures of zinc coatings: https://www.galvanizeit.org/resources/files/AGA%20PDFs/T_ZC_00.pdf
https://www.galvanizeit.org/about-hot-dip-galvanizing/what-is-hot-dip-galvanizing/the-hdg-coating/zinc-coating/
The European Galvanizers has a product fact file showing a similar Fe-Zn galvanize microstructure, with text available in 5 languages, e.g., the Spanish version at http://www.egga.com/fact/spanish/02/industry.htm
Ken Vlach [deceased]- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
Fe-Zn intermetallic compounds during galvanization
Q. When will Delta, Zeta, Gamma phases form during
Galvanization?
Does Aluminum in zinc bath affect the Fe-Zn phases?
- Hyderabad, Andhra Pradesh, India
June 24, 2013
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