Hot-dip galvanizing is used to coat iron or steel with a thin zinc layer. Galvanized steel is used in applications where rust resistance is needed. Hot-dip galvanizing is achieved by passing the steel through a molten bath of zinc at a temperature of around 860 °F (460 °C).
When exposed to the atmosphere the zinc reacts to form zinc oxide which further reacts with carbon dioxide to form zinc carbonate – a strong, grey corrosive-resistant material that protects the steel from the elements. The crystallization patterning on the surface is often referred to as a ‘spangle’.
Hot-dip galvanizing achieves a metallurgical bond between zinc and steel with a series of distinct iron-zinc alloys. Galvanized steel (sometimes called galvanized iron) can be used in much the same way as uncoated.
- Galvanized steel can be welded
- Suitable for high-temperature applications of up to 392 °F (200 °C)
- Temperatures above this will result in zinc peeling
- Steel strip can be hot-dip galvanized in a continuous line
- Used for applications requiring the strength of steel and resistance to corrosion.
- Applications include: roofing and walling, consumer appliances, metal pails, automotive body parts, heating and cooling duct systems