| 摘要 |
<p>The present invention provides a tool steel containing, 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% ofNi, 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, in which, when an area rate 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 rate of the coarse carbide in a cross section perpendicular to the forging direction is represented by T(%), the area rate L is 0.001 % or more, the area rate T is 0.001 % or more, and the ratio L/T is within a range from 0.90 to 3.00. The tool steel of the invention exhibits an isotropic size change in quenching and tempering.</p> |
