Form: This specification covers a premium-quality@ low-alloy steel in the form of bars@ forgings@ mechanical tubing@ and forging stock. Application: Primarily for critical bearing components requiring a through-hardenig steel usually with hardness of approximately 60 HRC and section thickness between 0.40 in. (10.16 mm) and 0.80 in. (20.32 mm) and subject to very rigid inspection standards.