This specification covers an aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.These products have been used typically for parts 0.80 inch (20.3 mm) and under in nominal 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 for parts of greater thickness but requiring proportionally lower hardness, but usage is not limited to such applications.
