This specification covers a premium aircraft-quality alloy steel in the form of bars, forgings 100 square inches (645 cm2) and under in cross-sectional area, and forging stock of any size.
This document establishes the requirements for the sequencing of processes relating to parts fabricated from 300M or 4340 modified steel heat treated to, or to be heat treated to, 270,000 psi (1860 MPa) minimum ultimate tensile strength (UTS) and higher.
This specification covers an aircraft-quality, low-alloy steel in the form of bars and forgings 1.50 inches or less in diameter or least distance between parallel sides (thickness).