Form:

This specification covers a special aircraft-quality, low-alloy steel in the form of bars.

Application:

These bars have been used typically for parts required to meet stringent magnetic inspection criteria, 0.75 inch (19.0 mm) and under in nominal thickness at time of heat treatment, requiring a through-hardening steel capable of developing hardness as high as 40 HRC when properly hardened and tempered, and also for parts of greater thickness requiring proportionately lower hardness, but usage is not limited to such applications.