BS 4659 specification is one British Standard which is mainly for Tool and die steels. BS 4659 specifies chemical composition, tolerances on dimensions and maximum depths of functional decarburization and recommends heat treatment temperature ranges for tool steel and die steels.

Similar to DIN ISO 4957 and ASTM A681, this standard BS 4659 is also widely used for almost all kinds of tool steels and die steels. Some common steel grades in BS 4659 are: High speed tool steels like BM2, BM42; Hot works tool steels like BH10, BH13; Cold work tool steels like BD2, BA2, BO1; Plastic moulding steels like BP20, BP30 etc.