This specification covers the requirements for heat-treatment of four classes of steel and the requirements for furnace equipment, test procedures and information for heat-treating procedures, heat-treating temperatures and material test procedures. It is applicable to all heat treatment of parts and to only the heat treatment of mill products which could affect its fabricability or the properties of parts. This specification also describes procedures which, when followed, will produce the desired properties and material qualities within the limitations of the respective alloys tabulated in Table IA, IB, IC and ID. Alloys other than those specifically covered herein may be heat treated using all applicable requirements of this specification.