What Is Galvanized Steel?

How does it work?

Galvanized steel is a carbon flat steel product with a zinc coating on its surface. This coating increases the corrosion resistance of steel coils, slit coils or sheets. The most common method for galvanized steel is hot-dip galvanizing.

During hot-dip galvanizing, the basic carbon steel coil is immersed in an acid bath to remove steel scales. Once the steel is cleaned and the scale is removed, it is continuously immersed in the molten zinc solution, forming a metallurgical bond and forming a protective coating under controlled coating weight. The coating weight immediately increases the corrosion resistance of the steel.

The zinc bath during hot-dip galvanizing contains trace elements, such as aluminum. The presence of these trace elements optimizes the adhesion of the coating, improves the forgeability of galvanized steel sheets, galvanized steel coils, and galvanized steel coils so that the material can form hundreds of thousands of products we use every day.

What is the spangle on galvanized steel?

In previous generations of steelmaking, galvanized steel sheets once contained large, flower-like zinc crystal patterns on the surface of the steel, called "spangle". Spangle is similar to large snowflakes in hexagons. Although today's galvanized steel still contains spangle, the spangle of galvanized steel produced by modern steel mills is almost invisible to the naked eye. This is called minimum spangle galvanized steel and zero spangles galvanized steel.

A common but disappearing misconception about a large galvanized steel sheet is that it has better corrosion resistance than the min spangle/zero spangle. But in fact, it's not. Minimum spangle and zero spangles galvanized steel’s smoother surface and smaller spangle form a better corrosive resistant coating.

What is the coating weight?

The weight of the galvanized layer of the above-mentioned galvanized steel is controlled by the steel mill during the production cycle and changes according to customer requirements and the end-use of the product. The weight of these coatings is directly proportional to the expected service life of the steel.

The weight of the galvanized layer is measured in ounces per square foot and ranges from G90 to G60, G40 and G30 galvanized steel. The service life of G90 galvanized steel is longer than that of G60, G40 and G30 galvanized steel, because the weight of the galvanized layer of G90 galvanized steel at 0.90 oz/ft^2 is lower than that of G60 galvanized steel at 0.060 ox/ft^2 The galvanized layer is heavier.

Daily use galvanized steel

The advantages of using galvanized steel are relatively low cost compared with stainless steel and other products, long service life, less maintenance and fast production speed. Therefore, galvanized steel is used in thousands of products that are seen and used around us every day.

Hot-dip galvanized steel is widely used in HVAC, construction, roofing, home appliances, containers, garbage, automobiles and other industries. For example, in the HVAC business, galvanized steel sheets, coils and slit coils (approximately 5.394" wide) are used to manufacture ducts and spiral ducts. Galvanized steel can be pre-coated, post-coated or bare.

The above information is provided by the galvanized steel coil factory.