Analyzing aluminum sheet metal grades

Most aluminum alloys combine iron, silicon, copper and manganese to adjust the metal’s strength or enhance other properties. Aluminum sheet metal grades identify alloy families and the metal’s composition. These grades include four numbers followed by a letter. 

When you look at an aluminum sheet metal grade, the first digit refers to the metal family or series. The letters that follow tell how the aluminum was processed. Here is an overview ofaluminum sheet metal grades.

Series of Aluminum Alloys: The First Digit

Use the following sheet metal grade chart to understand the series of aluminum.

What’s Behind the Letter?

Aluminum grades are followed by a letter, and that letter refers to the temper, or hardness, of the alloy. Each letter shares how the alloy was treated to achieve its properties. 

Here are a few letters you will see in aluminum grades: 

O = Aluminum was annealed at the mill. 

T = Aluminum was thermally treated.

H = Aluminum was work-hardened (or strain-hardened). 

T-Tempers

H-Tempers 

H-Tempers include two or more digits. The first digit indicates how the aluminum was work-hardened. 

H-tempers often include a second digit to show that the aluminum was work-hardened to a certain degree. 

2 = ¼ hard

4 = ½ hard

6 = ¾ hard

8 = fall hard

9 = extra hard