Detailed explanation of the characteristics and applications of galvanized coils
Date:2025-05-26View:35Tags:Epoxy pipe,Coated pipe,API casing
Galvanized coils are a basic metal material widely used in industrial manufacturing, construction, home appliances and other fields. Its core value lies in giving steel excellent anti-corrosion properties through the surface galvanizing process. This article will systematically introduce the definition, production process, classification, application scenarios and advantages of galvanized coils to help readers fully understand this important material.
1. Definition of galvanized coils
Galvanized coils are composite sheets with cold-rolled or hot-rolled steel coils as the base material and a layer of zinc metal layer on its surface through hot-dip or electroplating processes. The zinc layer reacts with oxygen and water in the air to form a dense basic zinc carbonate film (Zn₅(OH)₆(CO₃)₂), forming a physical and chemical dual protective barrier, which significantly slows down the rust rate of steel. Depending on the thickness of the zinc layer and process differences, the anti-corrosion life of galvanized coils can reach 10 to 50 years.
2. Production process and technology classification
Hot-dip galvanizing (HDG)
Process flow: steel coil → pickling and rust removal → immersion in molten zinc liquid (temperature about 460°C) → air knife to control the thickness of the zinc layer → cooling → surface passivation treatment.
Features: The zinc layer is thicker (usually 60~275g/m²), with strong adhesion, suitable for harsh outdoor environments.
Electrogalvanizing (EG)
Process flow: electrolytic cleaning of steel coil → deposition of zinc layer (thickness 10~50g/m²) through current in the electroplating tank → post-treatment (such as phosphating, oiling).
Features: The surface is uniform and smooth, easy to be subsequently coated, and is mostly used in precision manufacturing such as home appliances and automobiles.
3. Classification standards for galvanized coils
According to the galvanizing process: hot-dip galvanized coils, electrogalvanized coils.
By zinc layer thickness:
Conventional galvanizing (Z100~Z275, corresponding to zinc layer weight 100~275g/m²)
High zinc layer galvanizing (Z600 and above, used for heavy anti-corrosion scenarios).
By surface treatment: ordinary zinc flower, small zinc flower, no zinc flower (flat zinc layer), alloyed galvanizing (GA), etc.
IV. Core application areas
Construction industry
Roofing and wall enclosure systems (such as color steel plate substrates), steel structure anti-corrosion.
Auxiliary facilities such as ventilation ducts and cable trays.
Home appliance manufacturing
Refrigerator and washing machine shells, air conditioner indoor unit panels (mainly electrogalvanized sheets).
Automotive industry
Body parts, fuel tanks, chassis anti-rust parts (high-strength galvanized sheets account for more than 50%).
Agricultural and industrial equipment
Scenarios with weather resistance requirements such as granaries, greenhouse frames, and agricultural machinery shells.
5. Core advantages of galvanized coils
Excellent anti-corrosion performance: The sacrificial anode protection mechanism of zinc ensures that even if the coating is partially damaged, it can still delay the corrosion of the substrate.
Balance between economy and durability: Compared with stainless steel, the cost is reduced by 30%~50%, and the service life is extended by 3~5 times.
Processing adaptability: It supports stamping, bending, welding and other processes, and can be processed into complex components.
Environmental protection: Zinc can be 100% recycled, which is in line with the trend of green manufacturing.
6. Precautions for use and storage
Avoid storage in a humid environment: Long-term contact with water vapor may cause white rust (zinc oxidation product).
Processing protection: The temperature needs to be controlled during cutting or welding to prevent the zinc layer from burning.
Surface treatment matching: If the electro-galvanized sheet needs to be sprayed, it is recommended to perform phosphating or passivation treatment first.
