Chisel and steel for chisel

Patent metadata

Field	Value
Publication number	US-11186901-B2
Application number	US-201615566195-A
Country	US
Kind code	B2
Filing date	Mar 9, 2016
Priority date	Apr 21, 2015
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A steel constituting a chisel according to the present invention includes: 0.40-0.45% by mass of carbon, 0.50-0.80% by mass of silicon, 1.00-1.30% by mass of manganese, 0.001-0.005% by mass of sulfur, 2.90-3.80% by mass of chromium, and 0.20-0.40% by mass of molybdenum, with a balance consisting of iron and an unavoidable impurity, the steel has an ideal critical diameter DI defined by Equation (1) of 600 or more:DI=7·(% C)1/2·(1+0.64·% Si)·(1+4.1·% Mn)·(1+2.83·% P)·(1−0.62·% S)·(1+2.33·% Cr)·(1+3.14·% Mo)  (1).

First claim

The invention claimed is:

1. A steel body constituting by a steel consisting of:
0.40% by mass or more and 0.45% by mass or less of carbon (C);
0.50% by mass or more and 0.80% by mass or less of silicon (Si);
1.00% by mass or more and 1.30% by mass or less of manganese (Mn);
0.001% by mass or more and 0.005% by mass or less of sulfur (S);
2.90% by mass or more and 3.80% by mass or less of chromium (Cr);
0.20% by mass or more and 0.40% by mass or less of molybdenum (Mo); and
a balance consisting of iron and one or more unavoidable impurities with 0.020% by mass or less of phosphorous (P),
wherein the steel has an ideal critical diameter DI defined by Equation (1) of 600 or more:

DI
=

7
·

(

%
⁢

⁢
C

)

1
2

·

(

1
+

0.64
·
%

⁢
Si

)

·

(

1
+

4.1
·
%

⁢
Mn

)

·

(

1
+

2.83
·
%

⁢
P

)

·

(

1
-

0.62
·
%

⁢
S

)

·

(

1
+

2.33
·
%

⁢
Cr

)

·

(

1
+

3.14
·
%

⁢
Mo

)

wherein % is by mass, and
wherein the steel body is a rod having a diameter of at least 150 mm, and
a hardness (HRC) of an entire cross section of the steel body is within the range of from 49 to 54 HRC.

2. The steel body according to claim 1 , wherein a value of α defined by Equation (2) is 2.0 or more and 2.4 or less:
α=5·% C+3·% Si+% Mo−2·% Mn−10·% S  (2) where % is by mass.

3. The steel body according to claim 1 , wherein sulfur (S) is present at 0.001% by mass or more and 0.004% by mass or less.

4. The steel body according to claim 1 , wherein the steel has 3.01% by mass or more and 3.80% by mass or less of chromium (Cr).

5. The steel body according to claim 1 , wherein the steel has 3.36% by mass or more and 3.80% by mass or less of chromium (Cr).

6. The steel body according to claim 1 , wherein the steel has 0.27% by mass or more and 0.40% by mass or less of molybdenum (Mo).

7. The steel body according to claim 1 , wherein the steel body is a rod having a diameter of at least 160 mm.

8. A chisel constituted by a steel consisting of:
0.40% by mass or more and 0.45% by mass or less of carbon (C);
0.50% by mass or more and 0.80% by mass or less of silicon (Si);
1.00% by mass or more and 1.30% by mass or less of manganese (Mn);
0.001% by mass or more and 0.005% by mass or less of sulfur (S);
2.90% by mass or more and 3.80% by mass or less of chromium (Cr);
0.20% by mass or more and 0.40% by mass or less of molybdenum (Mo); and
a balance consisting of iron and one or more unavoidable impurities with 0.020% by mass or less of phosphorous (P),
wherein the steel has an ideal critical diameter DI defined by Equation (1) of 600 or more:

DI
=

7
·

(

%
⁢

⁢
C

)

1
2

·

(

1
+

0.64
·
%

⁢
Si

)

·

(

1
+

4.1
·
%

⁢
Mn

)

·

(

1
+

2.83
·
%

⁢
P

)

·

(

1
-

0.62
·
%

⁢
S

)

·

Assignees

• Komatsu Mfg Co Ltd

Inventors

• Amada Eiji
• Ochiai Akihiro
• Tsunekage Norimasa
• Nagaki Yuko

Classifications

• B25D17/02

  Percussive tool bits {(drill bits for earth drilling E21B10/00)} · CPC title

• E21C37/26

  Chisels or other cutting tools not mentioned before · CPC title

• C22C38/22 Primary

  with molybdenum or tungsten · CPC title

• E21B10/52

  with chisel- or button-type inserts · CPC title

• C22C38/00

  Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) · CPC title