Patent ID: 8012272

Claim:
A tool steel comprising, by mass percent, 0.55 to 0.85% of C, 0.20 to 2.50% of Si, 0.30 to 1.20% of Mn, 0.50% or less of Cu, 0.01 to 0.50% of Ni, 6.00 to 9.00% of Cr, 0.1 to 2.00% of Mo+0.5W, and 0.01 to 0.40% of V, with the balance of Fe and inevitable impurities, wherein the tool steel is characterized by an area percentage of a coarse carbide having a circle equivalent diameter of 2 μm or more in a cross section parallel to a forging direction is represented by L(%) and an area percentage of the coarse carbide in a cross section perpendicular to the forging direction is represented by T(%), the area percentage L is 0.001% or more, the area percentage T is 0.001% or more, and the ratio L/T is within a range from 0.90 to 3.00.