This specification covers a premium aircraft-quality alloy steel in the form of bars, forgings, mechanical turbing, flash welded rings, and stock for forgning or flash welded rings. These products have been used typically for parts requiring through-hardening, without liquid quenching, to a yield strength of 270 ksi (1862 MPa) and higher and where such parts may require welding during fabrication, but usage is not limited to such applications.