Hot work tool steel and hot work tool

Patent metadata

Field	Value
Publication number	US-12312665-B2
Application number	US-201917276827-A
Country	US
Kind code	B2
Filing date	May 9, 2019
Priority date	Oct 5, 2018
Publication date	May 27, 2025
Grant date	May 27, 2025

Abstract

The hot work tool steel or hot work tool contains, in mass %, 0.25 to 0.45% of C, 0.1 to 0.4% of Si, 0.5 to 0.9% of Mn, 0 to 0.6% of Ni, 4.9 to 5.5% of Cr, 1.3 to 2.3% of Mo or ½W by itself or 1.3 to 2.3% of (Mo+½W) in combination, 0.6 to 0.9% of V, and a balance of Fe and impurities, and value A and value B calculated by the following Formula 1 and Formula 2 satisfy that value A is 6.00 or more and value B is 1.00 or less.

Value A=−0.7(% Si)+1.5(% Mn)+1.3(% Ni)+0.9(% Cr)+0.6(% (Mo+½W))+0.3(% V)  Formula 1

Value B=1.9(% C)+0.043(% Si)+0.12(% Mn)+0.09(% Ni)+0.042(% Cr)+0.03(% (Mo+½W))−0.12(% V)  Formula 2.

First claim

What is claimed is:

1. A hot work tool steel containing, in mass %, 0.32 to 0.40% of C, 0.20 to 0.33% of Si, 0.5 to 0.9% of Mn, 0 to 0.6% of Ni, 5.2 to 5.5% of Cr, 1.3 to 1.46% of Mo or ½W by itself or 1.3 to 1.46% of (Mo+½W) in combination, 0.6 to 0.85% of V, and a balance of Fe and impurities, wherein
the hot work tool steel is manufactured in a manner that a material which is a steel ingot or a steel piece obtained by ingot-processing a steel ingot is used as a starting material,
a Charpy impact value of a Charpy impact test piece of the hot work tool steel in S-T direction with 2 mm U notch and a target hardness of 43 HRC is 30 J/cm 2 or more, and
the relationship of the content of each element calculated by the following Formula 1 and Formula 2 satisfies that value A is 6.55 or more and value B is 1.00 or less,
Value A=−0.7(% Si)+1.5(% Mn)+1.3(% Ni)+0.9(% Cr)+0.6(% (Mo+½W))+0.3(% V)  Formula 1

Value B=1.9(% C)+0.043(% Si)+0.12(% Mn)+0.09(% Ni)+0.042(% Cr)+0.03(% (Mo+½W))−0.12(% V)  Formula 2

wherein the content in mass % of each element is shown in parentheses.

2. The hot work tool steel according to claim 1 , wherein there is 0.2-0.5% of Ni in mass %.

3. The hot work tool steel according to claim 1 , wherein the hot work tool steel containing, in mass %, 0.32 to 0.40% of C, 0.20 to 0.33% of Si, 0.55 to 0.85% of Mn, 0 to 0.1% of Ni, 5.2 to 5.4% of Cr, 1.4 to 1.46% of Mo or ½W by itself or 1.4 to 1.46% of (Mo+½W) in combination, 0.65 to 0.80% of V, and a balance of Fe and impurities, and the relationship of the content of each element calculated by the Formula 1 and the Formula 2 satisfies that value A is 6.55 to 7.80 and value B is 0.90 to 1.00.

4. A hot work tool containing, in mass %, 0.32 to 0.40% of C, 0.20 to 0.33% of Si, 0.5 to 0.9% of Mn, 0 to 0.6% of Ni, 5.2 to 5.5% of Cr, 1.3 to 1.46% of Mo or ½W by itself or 1.3 to 1.46% of (Mo+½W) in combination, 0.6 to 0.85% of V, and a balance of Fe and impurities, wherein
the hot work tool is manufactured in a manner that a material which is a steel ingot or a steel piece obtained by ingot-processing a steel ingot is used as a starting material,
a Charpy impact value of a Charpy impact test piece of the hot work tool in S-T direction with 2 mm U notch and a target hardness of 43 HRC is 30 J/cm 2 or more, and
the relationship of the content of each element calculated by the following Formula 1 and Formula 2 satisfies that value A is 6.55 or more and value B is 1.00 or less,
Value A=−0.7(% Si)+1.5(% Mn)+1.3(% Ni)+0.9(% Cr)+0.6(% (Mo+½W))+0.3(% V)  Formula 1

Value B=1.9(% C)+0.043(% Si)+0.12(% Mn)+0.09(% Ni)+0.042(% Cr)+0.03(% (Mo+½W))−0.12(% V)  Formula 2

wherein the content in mass % of each element is shown in parentheses.

5. The hot work tool according to claim 4 , wherein there is 0.2-0.5% of Ni in mass %.

6. The hot work tool according to claim 4 , wherein the hot work tool containing, in mass %, 0.32 to 0.40% of C, 0.20 to 0.33% of Si, 0.55 to 0.85% of Mn, 0 to 0.1% of Ni, 5.2 to 5.4% of Cr, 1.4 to 1.46% of Mo or ½W by itself or 1.4 to 1.46% of (Mo+½W) in combination, 0.65 to 0.80% of V, and a balance of Fe and impurities, and the relationship of the content of each element calculated by the Formula 1 and the Formula 2 satisfies that value A is 6.55 to 7.80 and value B is 0.90 to 1.00.

Assignees

• Proterial Ltd

Inventors

• Nakano Yousuke
• Fukumoto Shiho
• Kataoka Kouta

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C22C38/44 Primary

  with molybdenum or tungsten · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/02 Primary

  containing silicon · CPC title

• C21D9/00

  Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor · CPC title