5.16.2 SAE – AISI
The SAE-AISI numbering system normally consists of
four digits. The first two digits (e.g., 86) provide
information about the elements used as alloys. The
last two digits refer to the percentage of carbon in the
steel in hundredths of 1 percent. (e.g., 20 means
0.20% C). For example, AISI 8620: