In article ,
"Jean-Paul Roy" wrote:

Am I correct assuming only 2024 is clad coated not 6061?

No -- 2024 comes in both clad and unclad versions. The unclad stuff is
usually heavier stock, for machining and major structural elements.

7075 is usually clad in sheet, but comes in unclad flavor, again, for
major structural elements.

Both 2024 and 7075 (especially) need corrosion protection.

I do not recall seeing clad 6061 or 5052. Other alloys may also exist as
clad.