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What Is Galvanized Steel Sheet?

A quonset hut made with galvanized steel sheet.
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  • Written By: M.R. Anglin
  • Edited By: Bronwyn Harris
  • Last Modified Date: 03 April 2014
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A galvanized steel sheet is a sheet of steel that has been galvanized in order to help prevent corrosion. These sheets can be used in a variety of applications including in furniture, cars, or in making tool boxes. The process is done in order to help steel stave off corrosion caused by exposure to other metals in the presence of an electrolyte or to oxygen and water. By putting on a barrier to coat the steel, a galvanized steel sheet is able to better resist the destructive forces acting against it. It must be noted, however, that this coating can deteriorate over time.

The effects of corrosion can be seen in many circumstances. For instance, a metal bucket can start to rust and deteriorate. Rust is a form of corrosion that occurs when certain metals are oxidized. If this reaction is allowed to continue, it can deteriorate a metal structure. Iron, one of the main components of steel, is prone to corrosion, and thus steel generally needs to be coated with a substance to prevent that phenomenon.

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The process of producing a galvanized steel sheet usually involves nothing more than dipping that sheet into very hot zinc. After the steel is galvanized, the zinc coating will react with oxygen in order to create zinc oxide, which further reacts with water, producing zinc hydroxide. In time, zinc hydroxide will react with carbon dioxide and form zinc carbonate, a gray layer that helps slow the reaction rate of the zinc and helps to protect the steel. The galvanizing process can also cause spangle on the surface of the steel. Spangle is the term used to describe the pattern that zinc grains can form on the surface of a galvanized steel sheet.

A galvanized coating is not a permanent solution. The protective layer of a galvanized steel sheet will corrode eventually, leaving the steel unprotected and prone to oxidization. In these cases, there is a simple solution in helping to keep the steel sheets protected: paint. Paint can provide the protection that the galvanized coating used to provide for the metal sheet. It should be noted that paint may not provide as good a protective barrier as a galvanized coating, but does provide a barrier between the steel and the elements to help stop the steel from corroding.

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Discuss this Article

StarJo
Post 6

I was surprised to hear that my dad got his fence from a steel supplier. It turns out that a lot of fences that appear to be wrought iron are actually made from galvanized steel shaped like fencing material!

My dad has a black fence with several tiny slats in between thicker black poles. The whole thing is curvy like an ocean wave, and it is topped with a curved banister all the way across.

If you get close to it, you can see little rough spots. They really make it look like iron, but they are really just side effects of the hot dip process. Even though they could not be prevented, they actually add to the appeal of the fence.

kylee07drg
Post 5

I have heard that many dishwashers and washing machines are made with galvanized steel. I got to visit an appliance manufacturing facility several years ago with my class, and we were told that they chose to use galvanized steel because of how well it stood up to corrosion.

While we were touring the facility, we saw giant galvanized steel coils lying around. I suppose this is how the sheet metal is stored. That way, they can unwind as much as they need and leave the rest rolled up for later use.

It was weird to see the steel all rolled up like that, though. Previously, whenever I thought of steel, I thought of thick chunks of heavy material. I never pictured giant rolls of thin sheets, because that just didn’t seem strong to me.

lighth0se33
Post 4

@OeKc05 - Yes, yours probably just hasn’t gotten old enough to rust yet. I had three of these bowls, and they all eventually rusted. So, I started buying ceramic bowls instead.

Galvanized steel is probably best used for things that don’t involve constantly being exposed to moisture. Even though it is coated with zinc, it cannot be expected to sit in water and stay rust-free.

I would think that furniture would be a good item to be made partially of galvanized steel sheet metal. My neighbor has a bunch of metal patio chairs that sit underneath an awning on her deck, and they don’t look rusty at all. I’m betting that they are made of galvanized metal.

OeKc05
Post 3

I have a coated steel dog water bowl that I bought because my puppy kept chewing up her plastic one. The label said that it was galvanized, but I didn’t know what that meant until reading this article.

I’ve only had it about a year, but it hasn’t rusted yet. Some of my friends say that theirs did get rusty, though.

Maybe it has stayed rust-free because she drinks so much water that I have to constantly refill it, so the water doesn’t sit still in there for very long. It could be that the bowl just isn’t old enough to have developed rust yet.

anon137518
Post 1

what is the shear stress value of galvanised iron sheet?

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