In the context of 1000 series aluminum designations, which statement is true?

• A. The last two digits denote percent purity, and 1030 equals 99.30% purity.
• B. The last two digits denote alloy additions.
• C. The last two digits indicate hardness.
• D. The last two digits indicate density.

Answer: (A)

In the 1000 series, the digits after the leading 1 show the minimum aluminum content by weight. So 1030 means the alloy is at least 99.30% aluminum, with the rest being trace impurities. This is why that statement is true. The last two digits do not indicate alloy additions, hardness, or density; those properties aren’t encoded in the designation (hardness varies with tempering, and density is essentially about 2.70 g/cm3 with only tiny changes due to impurities).