Q:What are the characteristics of galvalum steel coil?
A:Corrosion resistance: The aluminum-zinc alloy coating forms a dense oxide film (Al₂O₃) on the surface of the steel plate to prevent the spread of rust, and its corrosion resistance is 2-5 times that of traditional galvanized plates.
Heat resistance: The melting point of aluminum (660℃) is higher than that of zinc (419℃), and the coating is more stable at high temperatures and can withstand short-term high temperatures of 300℃ (such as painting and baking).
Processing performance: The coating is firmly bonded to the substrate and can adapt to processing processes such as stamping, bending, and rolling, and is not easy to crack or fall off.
Beauty and functionality: The surface can be silver-gray metallic luster or passivated (such as chromium-free passivation), which is both decorative and environmentally friendly.
Q:What are the key parameters of galvalum steel coils?
A:Coating weight
Unit: grams per square meter (g/m²), common specifications: 40/60/80/100/120 g/m² (double-sided total).
The higher the value, the stronger the corrosion resistance, and it needs to be selected according to the use environment (such as coastal areas require higher coating weight).
Substrate thickness
Common range: 0.15-4.0 mm, thin specifications (<0.5mm) are mostly used for home appliances, and thick specifications are used for building structures.
Surface treatment
Passivation: chromium-free passivation (environmentally friendly) or chromate passivation (traditional, fingerprint-resistant) to prevent white rust during transportation and storage.
Oil coating: Apply anti-rust oil to enhance short-term protection (need to be cleaned before processing).
Q:What are the main application areas?
A:Construction industry: roof panels, wall panels, rolling shutters, ventilation ducts; home appliance industry: refrigerators, air conditioner shells, washing machine drums, microwave oven cavities; automobile and transportation: automobile chassis parts, exhaust pipe brackets, highway guardrails, containers; industry and others: cable trays, equipment cabinets, solar brackets
Q:How to choose according to different needs?
A:1. Environmental factors
Outdoor/high humidity/salt spray environment: give priority to galvanized coils with a coating weight of ≥80 g/m².
Indoor dry environment: the coating weight can be reduced (such as 40-60 g/m²) to control costs.
2. Subsequent processing requirements
Painting required: select a substrate with appropriate surface roughness (such as "normal roughness" or "finished roughness") to ensure paint adhesion.
Deep stamping processing: confirm the elongation of the substrate (≥30% is preferred) and the adhesion of the coating (such as passing the bending test).
3. Environmental requirements
The EU and other markets must comply with regulations such as RoHS and REACH, and give priority to chromium-free passivation products.
Q:What are the common standards for galvalum coil?
A:International standards: ASTM A792 (USA), EN 10143 (Europe), JIS G3321 (Japan).
Chinese standards: GB/T 14978-2018