BS 2S 515 or more commonly referred to as S515 is a British Standard Aerospace Series, high strength alloyed steel available in sheet and strip form. S515 has a tensile range 460-600 MPa where its sibling S514 has a typical tensile range 770-1000 MPa when supplied in its hardened and tempered condition. Where S514 is supplied in the softened condition, it has a hardness only mechanical requirement which is the same as S515, and is therefore often duel released to both standards; BS S515/ S514 (softened condition).
Alloy Steel S515
High Strength Steel BS 2S 515, Specification for carbon-manganese steel sheet and strip (softened) (for use in the softened condition: 460/600MPa) (suitable for welding)