Aluminum-zinc-silicon-coated steel sheets and galvanized steel sheets (typically referring to pure galvanized steel sheets, such as hot-dip galvanized steel sheets) exhibit significant performance differences, primarily due to variations in coating composition and structure. The following comparison is based on multiple key performance dimensions:

1. Corrosion Resistance

Aluminum-zinc-silicon-coated steel sheets:

The coating contains 55% aluminum, 43.4% zinc, and 1.6% silicon, forming a dense aluminum-zinc-silicon ternary alloy crystalline layer. Aluminum forms an oxide film (aluminum oxide) on the surface, preventing corrosion media from penetrating; zinc protects the base material through its “sacrificial anode” effect. Its corrosion resistance is 3-6 times that of ordinary galvanized steel sheets, particularly in humid, high-humidity, or industrially polluted environments.  

For example, in coastal areas or industrial zones, the service life of aluminum-zinc-silicon-coated steel sheets can far exceed that of galvanized steel sheets.

Galvanized steel sheets:  

The coating is primarily zinc (pure zinc or zinc alloy), which provides corrosion protection through the sacrificial anode effect of zinc. However, the zinc oxide layer formed after zinc oxidation is relatively porous and prone to corrosion penetration when exposed to harsh environments over extended periods.

2. Heat Resistance

Aluminum-zinc-silicon-coated steel sheets:

They exhibit excellent heat resistance, capable of long-term use at 315°C (without discoloration or peeling) and can withstand short-term exposure to 370°C high temperatures. This is because aluminum has a high melting point (660°C), and the silicon in the coating stabilizes the alloy structure, preventing the coating from becoming brittle or peeling off at high temperatures.

Application scenarios: ovens, exhaust pipes, high-temperature pipelines, etc.  

Galvanized steel sheets:  

Poor heat resistance; zinc has a low melting point of 419°C. When temperatures exceed 100°C, the coating may oxidize and discolor; above 200°C, the zinc layer may soften, peel off, and cause the base material to rust.

Limited applications: Not suitable for long-term high-temperature environments.  

3. Thermal reflectivity  

Aluminum-zinc-silicon-coated steel sheets:  

Thermal reflectivity as high as 75%-80% (more than twice that of galvanized steel sheets), effectively reflecting sunlight and reducing heat absorption. In applications such as building roofs and exterior walls, it can lower indoor temperatures and reduce air conditioning energy consumption.

Galvanized steel sheets:  

Low thermal reflectivity (approximately 35%-40%), strong heat absorption, and prone to causing indoor temperature increases in summer.

4. Processing Performance

Aluminum-Zinc-Silicon Coated Steel Sheets:

The coating has strong adhesion and good flexibility, making it less prone to cracking or peeling during processing such as bending, stamping, or cutting. After processing, exposed cut edges can form a “self-healing” corrosion-protective layer through the sacrificial anode effect of zinc.

Additionally, the surface requires no complex pretreatment and can be directly subjected to secondary processing such as color coating or painting (only degreasing or passivation is needed).

Galvanized steel sheet:

It has good processing performance, but during deep stamping or severe bending, the zinc layer may exhibit “zinc embrittlement” (cracks or peeling); the protective effect of the zinc layer at cut edges is weak, requiring additional treatment (such as painting) to prevent rusting.

5. Economic Efficiency (Cost per Unit Area)

Aluminum-zinc-silicon-coated steel sheet:

The coating contains a higher proportion of aluminum, resulting in a larger coverage area per unit weight (due to aluminum's lower density than zinc). For example, at the same coating thickness, galvanized aluminum-zinc silicon steel sheets have approximately 9% more unfolded area per ton of steel than galvanized steel sheets, offering higher “yield rates” and lower long-term usage costs (longer lifespan, less maintenance).

Galvanized steel sheet:  

Initial procurement costs are lower, but due to poor corrosion resistance and short lifespan, long-term comprehensive costs may be higher (e.g., frequent replacements and maintenance).  

6. Appearance and Coating Compatibility  

Aluminum-zinc-silicon-coated steel sheet:  

The surface is silver-white with unique zinc-aluminum alloy crystalline patterns (“water ripple patterns”), offering high aesthetic appeal; Strong adhesion to coatings, with minimal risk of coating peeling after color coating.

Galvanized steel sheets:

Surface appears blue-white (hot-dip galvanized) or silver-gray (electrogalvanized), with no distinct patterns; if the zinc layer oxidizes unevenly, it may affect coating adhesion, requiring stricter pretreatment.