| 摘要 |
<p>Provided are a hot work tool steel having improved toughness and a process of producing the hot work tool steel. A hot work tool steel comprising, in mass%, 0.3% or more and less than 0.6% of C, 1.5% or less of Si, 1.5% or less of Mn and 3.0% or more and less than 6.0% of Cr, wherein more than 0.0025% and 0.025% or less of Zn and 0.005% or more of P are contained and the Zn/P ratio is more than 0.5; and a process of producing a hot work tool steel, comprising a first step of preparing a molten steel having a chemical composition of a hot work tool steel containing 0.005 mass% or more of P, a second step of adding Zn to the molten steel having the chemical composition of the hot work tool steel, and a third step of casting the Zn-added molten steel to produce a steel ingot, wherein the second step is a step of adding Zn in such a manner that more than 0.0025 mass% and 0.025 mass% or less of Zn and 0.005 mass% or more of P can be contained in the chemical composition of the steel ingot after the casting in the third step and the hot work tool steel can have a Zn/P ratio of more than 0.5.</p> |
