What is Aluminized Silicon Steel Sheet, and how does it differ from standard aluminized steel?

Question

Accepted Answer

Aluminized Silicon Steel Sheet (commonly referred to as AS sheet or Type 2 aluminized steel) is a high-performance steel product produced by hot-dip coating a low-carbon or high-strength steel substrate with an aluminum-silicon alloy layer — typically comprising approximately 90% aluminum and 5–11% silicon. The addition of silicon significantly improves coating adhesion to the base metal, suppresses the growth of brittle iron-aluminum intermetallic compounds, and preserves coating ductility and bond strength at elevated temperatures.

MESCO Key Insight

Compared to pure aluminized steel (Type 1), aluminized silicon steel (Type 2 / AS sheet) exhibits approximately 30% lower oxidation rates in high-temperature environments ranging from 600–900 °C, making it the preferred material for automotive exhaust systems, industrial furnace linings, and appliance cavity components.

The key differences are summarized in the table below:

Comparison	Standard Aluminized Steel (Type 1)	Aluminized Silicon Steel (AS / Type 2)
Coating Composition	Pure aluminum or Al-Zn alloy	Aluminum + 5–11% Silicon
Max. Service Temperature	Approx. 450 °C	700–900 °C (up to 1000 °C short-term)
Coating Adhesion	Moderate	Excellent (silicon inhibits brittle layer growth)
Corrosion Resistance	Good	Superior (self-healing high-temp oxide film)
Typical Applications	Building cladding, appliance exteriors	Automotive exhaust pipes, furnace linings, heat treatment equipment

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