Patent ID: 7695576

Claim:
A low alloy high speed tool steel, which consists essentially of, by weight %, C: 0.50-0.75%, Si: 0.02-2.00%, Mn: 0.1-3.0%, P: up to 0.050%, S: up to 0.010%, Cr: 5.0-6.0%, W: 0.5-2.0%, V: 0.70-1.25%, Al: up to 0.1%, O: up to 0.01% and N: up to 0.04%, Mo in an amount satisfying the relationship [Mo+0.5W](Mo-eq.) is 2.5-5.0%, and the balance of Fe, wherein Mo-eq./V is 2-4, the steel contains carbides of, in the annealed state, [MC+M 6 C] and/or M 23 C 6 (M 7 C 3 ); and after quenching from a temperature of 1100-1200° C., the steel contains one of substantially no remaining carbide and remaining carbides of MC, the steel has a 10R Charpy impact value equal to or greater than about 120 J/cm 2 , the steel has a hardness (HRC) equal to or greater than about 58, and a difference between hardness by oil quenching and hardness by controlled quenching of the steel is less than or equal to 0.5.