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[deleted] t1_isg380z wrote

[removed]

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ekjustice t1_isge6q2 wrote

It has a current going through the liquid and into the metal object, that's why they call it "galvanized". The electricity bonds the zinc to the steel better than just dipping it.

Some items are just dipped in liquid zinc "hot dipped". This leaves more zinc on the item and tends to be more expensive.

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the_snook t1_isghskh wrote

It can also depend on the type of coating. Some "galvanized" steel is actually Zincalume, which is coated with a zinc-aluminium-silicon alloy. From memory, I think Zincalume has more prominent crystal structure (though maybe it was just because of the particular manufacturer of the stuff I saw).

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JenJudy t1_ishjwho wrote

The term galvanized originally meant electroplated, and didn't specify what metal was used, but it gradually came to mean primarily electroplating with zinc. In modern usage, it simply means coated with zinc, regardless of whether it's electroplated or hot dipped, at least according to Merriam-Webster who give this definition:

>: to coat (iron or steel) with zinc

>especially : to immerse in molten zinc to produce a coating of zinc-iron alloy

This is consistent with the way the term is used indescribing finishes on bolts, etc, by both professional sources such as McMaster or consumer sources such as home depot. The most common options are called zinc plated, which is electroplated, and hot dip galvanized, which does not involve an electric chemical process, in contrast to the origin of the term.

It's surely irritating to electrochemists that the meaning has shifted to go beyond electrochemical processes, but language change is inevitable.

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BigBobby2016 t1_isg69jf wrote

Is there any galvanized steel that doesn’t have patterns? OP says “some”

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shouldco t1_isgah1l wrote

Yes and no.

The prominence of the patten varies to the point of not being discernible. In theory you could have a single crystal but let's just say that is practically impossible for anything commercially produced.

Basically each section of the pattern is a single crystal of zinc. Which means there was basically one nucleation point every 1/2 a square inch or so. In order to get that few you need a pretty smooth piece of steel so it is more prominent on things like cold rolled steel and sheet metal. Stuff like cast steel has a very rough texture and can have thousands of nucleation points per sqin and as such you will basically just see a flat gray color with the naked eye.

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Br4veSirRobin t1_isghn1y wrote

It's called galvanneal and it is used in painted car panels. After dipping in zinc the steel goes through a furnace to slow nucleation-crystallization. It is a matte gray finish and paint sticks to it very well.

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LameTrouT OP t1_isgicpz wrote

I believe they must do this for hand rails ls that get a color after getting gavinized?

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Br4veSirRobin t1_isgj7kg wrote

The patterns on the surface of galvanized steel are called 'spangle'. People who use galv steel order spangle size. Antimony is used in the molten zinc bath for spangle size control among other process controls. Metallurgist here.

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cr0n1c t1_ish88jy wrote

So far down to find someone finally saying Spangle. Thank you.

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Br4veSirRobin t1_isgirrk wrote

True. Any painted galvanize is is usually galvanneal. I was a metallurgical engineer in both carbon steel and titanium.

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shouldco t1_isgmwn7 wrote

Thank you, I was unfamiliar with that industrial application.

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