What is the approximate depth of the pure aluminium coating in Alclad relative to total sheet thickness?

What is the approximate depth of the pure aluminium coating in Alclad relative to total sheet thickness?

• A. 1.5% to 5%
• B. 10% to 15%
• C. 0.5% to 1%
• D. 20% to 30%

Answer: (A)

The protective role of Alclad comes from a thin layer of high-purity aluminum on the surface, which forms a corrosion-resistant barrier while leaving most of the sheet’s strength to the core alloy. That pure aluminum skin is deliberately kept very thin relative to the total sheet thickness—typically only a few percent. In practice, the coating depth is about 1.5% to 5% of the total thickness. This range provides effective corrosion protection and helps prevent galvanic attack if the outer surface is damaged, without adding significant weight or compromising formability or strength. If the coating were much thicker, weight and manufacturing issues would rise; if it were much thinner, corrosion protection would be less reliable.

The protective role of Alclad comes from a thin layer of high-purity aluminum on the surface, which forms a corrosion-resistant barrier while leaving most of the sheet’s strength to the core alloy. That pure aluminum skin is deliberately kept very thin relative to the total sheet thickness—typically only a few percent. In practice, the coating depth is about 1.5% to 5% of the total thickness. This range provides effective corrosion protection and helps prevent galvanic attack if the outer surface is damaged, without adding significant weight or compromising formability or strength. If the coating were much thicker, weight and manufacturing issues would rise; if it were much thinner, corrosion protection would be less reliable.