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.
AISI O2 Steel is an oil hardening tool steel supplied in the annealed condition. ASTM O2 steel is widely used for universal use. It's similar to AISI O1 grade tool steel, with addition of Mo element.
ASTM/AISI A2 tool steel is a versatile, air hardening chromium alloy tool steel that replaces O1 tool steel when safer hardening, less distortion and increased wear resistance are required.
AISI H12 steel is a 4.75~5.5% chromium, general-purpose hot work tool steel. ASTM/AISI H12 Steel is a deep-hardening, air-hardening steel that exhibits minimal size change during heat treatmnet.
H10 Tool Steel is one chromium hot-work tool steel that exhibits excellent resistance to softening at elevated temperature. H10 tool steel is recommended for difficult hot work tooling applications.