This specification covers an aircraft-quality, low-alloy steel in the form of bars.These bars have been used typically for parts 0.50 inch (12.7 mm) and under in section thickness at time of heat treatment requiring a through-hardening steel capable of developing hardness as high as 50 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.
