This specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock. These products have been used typically for nitrided parts requiring high surface hardness, resistance to heat, and less distortion than parts made from steel requiring quenching to case harden and subject to very rigid inspection standards, but usage is not limited to such applications. This steel may be case hardened in dissocaited ammonia gas to provide a minimum case hardness of 900 HV.