1.1 This specification covers the requirements for quenched and tempered alloy steel hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws M3 through M20 thread sizes having material properties of ISO 898/1 Property C This specification covers the requirements for quenched and tempered alloy steel hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws. The screws shall be fabricated from alloy steel made to fine grain practice. The chemical compo