Sheet metal identification numbers

A. Hi Jams. I can't say that such numbers always indicate the type of metal, but the two examples you provided do.

2024-T3 means aluminum of type 2024 with a T-3 temper. Aluminums in the 2xxx series are aluminum-copper alloys, and 2024 is one specific composition. T-3 means solution heat treated and cold worked.

18/8 stainless means stainless steel comprised of 18 percent chromium and 8 percent nickel.

There are numerous numbering systems for various metals, and unfortunately there are few easily discernible patterns. Good luck.

A. The numbers stamped on to the back of metals are there to help identify the type of metal and alloy that makes up that particular sheet of metal. For example the 2024 the 2000 series is aluminum the numbers that follow the 20 is the other metals that are present in that compound for example 24 is magnesium. Very rarely are you to find a metal that is 100% pure because, for one, they rarely exist in nature; and two, if they do they are too rare to be used for common sheet metal that me or you could afford. Secondly the T-? whatever the number 1,2,3 whatever it may be is the temper effect and mechanical properties of that metal. For common household or automotive applications these numbers don't mean a whole lot but when you get into aircraft or other high speed applications such things become very important.