plating, anodizing, & finishing Q&As since 1989
Substitutability between galvannealed, hot dip galvanized and electrogalvanized
Please could you make a comparison between galvannealed, hot dip galvanized and electrogalvanized based on interchangeability, price, consumer preference etc..
Thank you very much !
There is essentially no interchangeability. or at least very little--
In hot dip galvanizing, metal is put into a bath of molten zinc, which adheres and forms a coating. This coating is often 'spangled' , the familiar bright crystalline look of metal garbage cans, sheet metal ducting, etc. This is usually a final finish, although it can be painted if need be, but not easily.
In galvannealing, the same hot dip process is used but the parts are immediately annealed in a way that forms an iron-zinc alloy, which is a harder surface and much more easily painted. Galvannealed surfaces are invariably painted.
In zinc electroplating, electrical current causes the zinc to be deposited on the base metal. Zinc electroplating can be, and almost always is, far thinner than hot dip galvanizing. This means it affords galvanic corrosion protection for a shorter time. Zinc plating is more for interior applications than exterior applications. It is more decorative (brighter), less expensive, and causes less problems with 'fit' of nuts and bolts because it's thinner.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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