Tool steels and manufacturing method thereof
AssigneeDaido Tokushuko Kabushiki Kaisha
InventorTakayuki Shimizu
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Abstract
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% of Ni, 6.00 to 9.00% of Cr, 0.1 to 2.00% of Mo+0.5 W, 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.
Claims14
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.
Dependencies are inferred from the claim text.