In everyday language, the terms “sheet metal” vs. “steel” and “zinc-coated” vs. “galvanized” are often used interchangeably. To make things clearer, let’s look at each term individually.
Sheet Metal vs. Steel
- Steel: An alloy of iron with a small amount of carbon and other elements. Steel is hard, highly durable, and used extensively in construction, mechanical engineering, and machine manufacturing.
- Sheet metal: A product rolled thin from a steel plate. Sheet metal is simply steel in thin-sheet form. It can be made from various grades of steel, as long as the steel has sufficient ductility.
In short: steel is the base material, while sheet metal is a product made from steel. Sheet metal is thin-gauge steel (generally 2–3 millimeters or less; anything thicker is usually called steel plate). In the cable tray and electrical enclosure industry, thin steel sheet is the material mainly used, which is why we commonly call it “sheet metal”.
Zinc-Coated vs. Galvanized
“Zinc-coated” and “galvanized” both essentially refer to “plating” — applying a layer of zinc onto the surface of sheet metal or steel to protect it from oxidation (rust). Common methods for applying a zinc layer to a steel surface include:
- Chemical plating
- Electroplating
- Hot-dip galvanizing
One point of confusion: before galvanized sheet reaches the market, people often mistakenly assume it was electroplated. In fact, it is usually still hot-dip galvanized, produced using modern technology at large mills.
In the industry, we use the term “zinc-coated” rather than “galvanized” to avoid confusion with “hot-dip galvanized” — even though, in practice, both usually refer to the same hot-dip galvanizing process.
- Zinc-coated sheet means using sheet that was already galvanized at the mill, which is then formed into the finished product.
- Hot-dip galvanizing means fabricating the product first from hot- or cold-rolled sheet/steel, and only afterward sending it through the hot-dip galvanizing process. Not sure what hot-dip galvanizing is? See our article on hot-dip galvanizing.
In Summary
Whether you call it “sheet metal” or “steel”, “zinc-coated” or “galvanized”, the difference mainly comes down to naming conventions rather than the underlying material or process.
