This specification deals with the standard requirements for superstrength alloy steel forgings for highly stressed structural members. Covered here are eight types (twenty-seven grades) of alloy steels, namely: quenched and tempered steels (Grades 11, 12, 12a, 13, 21, 22, 23, 31, 32, and 33); air hardened steel (Grade 41); martensitic stainless steels (Grades 51, 52, and 53); No. 1 precipitation hardened stainless steel (Grade 61); No. 2 precipitation hardened stainless steel (Grade 64); No. 3 precipitation hardened stainless steels (Grades 62 and 63); maraging steels (Grades 71, 72, 73, 74, and 75); and miscellaneous steels (Grades 81, 82, 83, and 84). The steels shall be manufactured by melting process and shall be finished by hot-worked forging. Forgings may be furnished in one of the following conditions: stress relieving; annealing; solution treatment; solution treatment and ageing; normalizing; normalizing and tempering; or quenching and tempering. Heat and product analyses shall be employed to assess the conformance of steels with required chemical compositions. Forgings shall examined by tension and Charpy impact tests and conform to required mechanical properties such as yield strength, tensile strength, elongation, reduction of area, minimum room-temperature Charpy V-notch energy absorption, maximum annealed hardness, and section size capability. Nondestructive tests, such as magnetic particle, liquid penetrant, and ultrasonic inspection procedures, shall also be performed.

1.1 This specification covers requirements for forged steel shapes for highly stressed structural members requiring yield strengths in excess of 140 ksi [965 MPa].

1.2 This specification is not intended for applications limited by creep deformation.

1.3 Twenty-eight grades are covered by this specification. Selection will depend upon design, service conditions, and mechanical properties required.

1.4 Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the order.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.6 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch-pound units.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.