This specification, in conjunction with the general requirements for steel heat treatment covered in AMS2759, establishes the requirements for heat treatment of low-alloy steel parts to minimum ultimate tensile strengths of 220 ksi (1517 MPa) and higher. Parts are defined in AMS2759. The requirements for heat treatment of alloy Aermet100 are no longer part of this specification and can be found in AMS2759/3. Due to the limited hardenability of these materials, size limits have been added to this specification.