Hebei Yehui Metal Materials Co., Ltd.

The difference and use of galvanized coating on steel coils

The differences and uses of galvanized steel coil coatings are mainly reflected in surface treatment, corrosion resistance, mechanical properties, processing technology, economic cost, and typical application scenarios.

Surface treatment and corrosion resistance

Galvanized steel coils form a zinc layer on the surface of the steel coil through hot-dip galvanizing or electro-galvanizing processes. The thickness of the zinc layer of hot-dip galvanizing is usually ≥45μm, while the thickness of electro-galvanizing is between 5-15μm. The zinc layer corrodes preferentially as a sacrificial anode to form a zinc oxide/zinc carbonate protective film, which significantly improves corrosion resistance. In industrial environments, the corrosion resistance of galvanized steel coils can reach 10-20 years, and in marine environments, it also has a corrosion resistance of 5-10 years. In contrast, ordinary steel coils rely only on the oxide layer of the substrate itself (such as Fe₂O₃/Fe₃O₄), and the corrosion rate is faster. It can only last for 1-3 years in industrial environments and even less than 1 year in marine environments.

Mechanical properties and processing technology

The galvanizing process will slightly increase the yield strength of the steel coil (about 5-10MPa), but it does not affect its low-temperature toughness. When stamping galvanized steel coils, the mold gap needs to be controlled (galvanized layer thickness + 0.02mm) to avoid zinc layer peeling. Low-hydrogen welding materials should be used during welding, and the welding heat input should be controlled to avoid zinc layer burning. The work hardening effect of ordinary steel coils is not obvious, and the mold gap can be designed according to the thickness of the substrate.

Typical application scenarios

Galvanized steel coils are widely used in building structures (such as steel structure workshops, photovoltaic brackets, curtain wall keels), home appliance manufacturing (such as refrigerator shells, washing machine inner drums, air conditioning ducts), automotive industry (such as chassis anti-corrosion parts, exhaust pipe sheaths) and energy industries (such as photovoltaic panels). Ordinary steel coils are used in places where high rust prevention is not required, such as rebar, steel sections, and internal supports.