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Galvanized sheet metal steel and corrosion

2002

Galvanized Sheet metal Steel and corrosion.

I am looking at cost saving measures for our zinc bronze chromate plated steel. I am considering switching to Galvanized Steel, but I am concerned with the punched unplated edges that will be visible. Is there a concern of the edges of galvanized steel corroding?

I am also concerned with possible electrolysis between the galvanized sheet metal that is in contact with zinc bronze chromate plated steel. Are there any issues with these dissimilar plating materials corroding each other?

Thanks for your help,

Ross Macfarlane
Power Measurement - Saanichton, BC, Canada

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2002

As long as you are not building something exotic like an airplane or spaceship, I would't worry about galvanic problems between zinc plating (electrogalvanizing) and galvanizing (hot dip zinc plating). Actually, the galvanized material will have a chromate coating on it too as zinc will readily 'white rust' without it.

The sheared edges of preplated or pregalvanized sheet will become rust colored. If they are visible, preplate or pregalvanize may not be a very good option.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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I am using 8Ga Galvanized sheetmetal to make a bracket. I am also concerned about edge corrosion. It is mainly an appearance issue. Do you have any photographs of corrosion on similar materials at various time intervals?ASTM B117 4, 24, 96 after hours would be ideal.

Thanks!

Lenny Delvecchio
industrial control equipment - Milwaukee, Wisconsin
2004

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