Galvalume steel
Generally, galvalume (GL) steel is an Al-Zn alloy, which uses cold-rolled steel sheets as substrates and then solidifies 55% aluminium, 43.4% zinc, and 1.6% silicone at a high temperature of 600°C. This unique “aluminum-iron-silicon-zinc” structure combines the physical protection and high durability of aluminium with the electrochemical protection property of zinc. Therefore, GL steel is more resistant and outlasts galvanized steel sheet.
Roles of various composition materials:
- Aluminium: can offer strong thermal resistance, long service life, and heat resistance.
- Zinc: can offer anti-corrosion ability.
- Silicon: can offer heat resistance.
Advantages of galvalume Steel
- 1. Strong Corrosion Resistance: GL steel is more resistant than galvanised (GI) steel due to the double protection of zinc and aluminium. That is, when the zinc is worn away, the aluminium will form a dense layer of aluminium oxide, preventing corrosive substances from further corroding the steel interior. This also means it has a “self-healing” ability.
- Attractive Appearance: Galvalume has a silvery-white colour and smooth surface. And there are many delicate “zinc flowers” that are highly appreciated when used as a building material.
- Heat Resistance: It has a good heat resistance and can withstand high temperatures of more than 300°C. Its thermal reflectivity is also very high, twice that of galvanized steel, thus it is often used as a thermal insulation material.
- Paintability: Due to the good adhesion between galvalume steel coating and paintings, it can be painted directly without any pretreatment and weathering. Like hot-dipped galvanized steel, it has good workability and weldability, and can accommodate cold bending, stamping, etc., without doing damage to steel surface.
- Long Service Life: Tests conducted under the same outdoor conditions show that the service life of galvalume steel is more than two times that of galvanized steel. Research conducted by the Metal Construction Association (MCA) indicates that galvalume steel can be expected to provide at least twice the service life of traditional zinc-coated steel under the same exposure conditions. It means galvalume steel could last 50 ~ 60+ years before the corrosion begins to show.
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