Primarily for heat treated parts and structures that may require welding during fabrication and may be through-hardened to a minimum tensile strength of 270,000 psi (1862 MPa) in sections of 2 in. (50 mm) or less in nominal thickness. This specification has been declared "Noncurrent" by the Aerospace Materials Division, SAE, as of April 1, 1987. It is recommended that this specification not be specified for new designs.
