Steel for mold, and mold

Patent metadata

Field	Value
Publication number	US-11535917-B2
Application number	US-202016952994-A
Country	US
Kind code	B2
Filing date	Nov 19, 2020
Priority date	Dec 3, 2019
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

The present invention relates to a steel for mold, containing: 0.28 mass %≤C≤0.65 mass %, 0.01 mass %≤Si≤0.30 mass %, 1.5 mass %≤Mn≤3.0 mass %, 0.5 mass %≤Cr≤1.4 mass %, 1.9 mass %≤Mo+W/2≤4.0 mass %, 0.2 mass %≤V≤1.0 mass %, and 0.01≤N≤0.10 mass %, with the balance being Fe and inevitable impurities, in which, in a state after quenching and tempering, the steel has: a (Mo, W) carbide having a diameter of 0.2 μm or less being in an amount of 1.2 mass % or more, a ratio (mass ratio) of the amount of the (Mo, W) carbide to an amount of a Cr carbide being 11 or more, and a hardness change of 15 HRC or less.

First claim

What is claimed is:

1. A steel for mold, consisting of:
0.28 mass %≤C≤0.65 mass %,
0.01 mass %≤Si≤0.30 mass %,
1.5 mass %≤Mn≤3.0 mass %,
0.5 mass %≤Cr≤1.4 mass %,
1.9 mass %≤Mo+W/2≤4.0 mass %,
0.2 mass %≤V≤1.0 mass %, and
0.01≤N≤0.10 mass %,
optionally,
Al≤1.5 mass %,
Ti≤0.5 mass %,
Nb≤0.5 mass %,
Zr≤0.5 mass %,
Ta≤0.5 mass %,
Co≤1.0 mass %,
Ni≤1.0 mass %,
Cu≤1.0 mass %,
S≤0.15 mass %,
Ca≤0.15 mass %,
Se≤0.35 mass %,
Te≤0.35 mass %,
Bi≤0.50 mass %, and
Pb≤0.50 mass %,
with the balance being Fe and inevitable impurities,
wherein, in a state after quenching and tempering, the steel comprises:
a (Mo, W) carbide having a diameter of 0.2 gm or less being in an amount of 1.2 mass % or more,
a ratio (mass ratio) of the amount of the (Mo, W) carbide to an amount of a Cr carbide being 11 or more, and
a hardness change of 15 HRC or less.

2. The steel for mold according to claim 1 , satisfying at least one condition selected from the group consisting of:
0.005 mass %≤Al≤1.5 mass %,
0.01 mass %≤Ti≤0.5 mass %,
0.01 mass %≤Nb≤0.5 mass %,
01 mass %≤Zr≤0.5 mass %, and
0.01 mass %≤Ta≤b 0.5 mass %.

3. The steel for mold according to claim satisfying:
0.01 mass %≤Co≤1.0 mass %.

4. The steel for mold according to claim 1 , satisfying at least one condition selected from the group consisting of:
0.30 mass %≤Ni≤1.0 mass %, and
0.30 mass %≤Cu≤1.0 mass %.

5. The steel for mold according to claim 1 , satisfying at least one condition selected from the group consisting of:
0.01 mass %≤S≤0.15 mass %,
0.001 mass %≤Ca≤0.15 mass %,
0.03 mass %≤Se≤0.35 mass %,
0.01 mass %≤Te≤0.35 mass %,
0.01 mass %≤Bi≤0.50 mass %, and
0.03 mass %≤Pb≤0.50 mass %.

6. The steel for mold according to claim 1 , having, in the state after quenching and tempering, an initial hardness of 52 HRC or more.

7. The steel for mold according to claim 1 , having, in the state after quenching and tempering, a thermal conductivity at room temperature of 30 W/(m·k) or more.

8. The steel for mold according to claim 1 , satisfying:
0.01 mass %≤N≤0.05 mass %.

9. The steel for mold according to claim 1 , wherein, in a state before the quenching and the tempering, a soaking treatment is performed at 1,200° C. or higher.

10. The steel for mold according to claim 1 , wherein, in a state before the quenching and the tempering, a soaking treatment is performed at 1,200° C. or higher after melt casting and before hot forging.

11. The steel for mold according to claim 1 , wherein, in a state before the quenching and the tempering, a soaking treatment is performed after melt casting and before hot forging.

12. The steel for mold according to claim 1 , satisfying:
2.0 mass %≤Mn≤3.0 mass %.

13. The steel for mold according to claim 1 , satisfying:
0.55 mass %≤C≤0.65 mass %, and
wherein, in a state before the quenching and the tempering, a soaking treatment is performed.

14. The steel for mold according to claim 1 , satisfying:
0.55 mass %≤C≤0.65 mass %,
wherein, in a state before the quenching and the tempering, a soaking treatment is performed at 1,200° C. or higher.

Assignees

• Daido Steel Co Ltd

Inventors

• Umemori Naoki
• Higuchi Shigeki

Classifications

• C22C38/22

  with molybdenum or tungsten · CPC title

• B33Y70/00

  Materials specially adapted for additive manufacturing · CPC title

• B33Y80/00

  Products made by additive manufacturing · CPC title

• C22C38/58

  with more than 1.5% by weight of manganese · CPC title

• C22C38/30

  with cobalt · CPC title