Definition - What does Galfan mean?
Galfan is hot-dip galvanized steel with a two-sided coating composed of zinc-aluminum alloy. It consists of 95% zinc and 5% aluminum in a solid solution with improved corrosion resistance and formability compared to zinc alone. Galfan improves corrosion resistance by 50% or more over traditional galvanization.
Galfan can be used to replace thick galvanized coating and post-galvanizing treatments. In certain applications, a 10-micron galfan coating can replace a 20-micron galvanized coating, providing better weldability, drawability and corrosion resistance. Thus, it reduces costs, simplifies secondary processes and eliminates the need for post-treatment.
Corrosionpedia explains Galfan
Galfan can lower costs via lighter coating weights while achieving similar or better performance than standard galvanization. Galfan is obtained by continuous hot-dip coating in a bath of molten metal consisting of approximately 95% zinc and 5% aluminum.
Advantages of galfan include:
- No spangle
- Low coefficient of friction
- Improved formability
- Enhanced resistance to micro-cracking
- Excellent paint adhesion
- Environmentally friendly (reduces zinc usage up to 50%)
Galfan has a cellular surface which appears mottled. Unpainted galfan acquires a patina over time, its initial metallic appearance dulls to a matte gray. Galfan has a eutectic structure, giving it excellent ductility, and the thin intermetallic layer at the steel/coating interface guarantees excellent coating adhesion. These two properties enable galfan to be used for making components that are particularly difficult to form.
Galfan's superior corrosion resistance allows it to be an alternative to thicker galvanized coatings and post-galvanization treatments. Sacrificial protection provides effective corrosion resistance at sites of mechanical damage (impact, scratches, gravel impingement) and also prevents corrosion of cut edges. The use of pre-lubricating oils and of thin organic films can further improve drawing properties.
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