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Galvanneal vs Electro-Galvanneal?

Q. I am trying to properly specify the material for a part we now call out as CS Type B per ASTM A653 [affil. link], which we call "electrogalvannealed" and I think this is incorrect. I have seen galvanneal defined as hot-dip galvanized with the extra heating step to form the zinc-iron diffusion layer. Is electro-galvanneal just electro-galvanized with the same heating step added? If so, then it seems ASTM A653 [affil. link] would not be the correct specification, so is there a correct one?

Gerry Maynard
Mechanical Engineer - West Greenwich, Rhode Island, USA
July 20, 2010

A. You have the correct understanding of hot-dip galv and the subsequent galvanneal process. Things are a little different though when the coating is applied by an electroplating process rather than by immersion into molten metal. The bath chemistry is specifically adjusted so that zinc, zinc-iron, or zinc-nickel coatings are directly deposited, which means that a subsequent furnace is not required. Electroplated steel sheet specifications include ASTM A879 [affil. link], ASTM A917 [affil. link], and ASTM A918 [affil. link].

Toby Padfield
- Michigan, USA

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