High Speed Steels - M-2, M-35, M- 42, T-1, T-2, T-3, T-4, T-5, T-6,etc.
Hot Work Tool Steel (Hot Die Steels) - H-11, H-13, H-20, H-21, etc.
Cold Work Tool Steels (HCHCr, OHNS, Shock Resisting) - D-2, D-3, D-6 / O-1, O-2, O-6, CW-1 / S-1, S-2, S-3, etc.