Chisel and steel for chisel
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).
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
)
·
(
1
+
2.33
·
%
Cr
)
·
(
1
+
3.14
·
%
Mo
)
wherein % is by mass, and
wherein the chisel has a diameter of at least 150 mm, and
a hardness (HRC) of an entire cross section of the chisel vertical to an axial direction of the chisel is within the range of from 49 to 54 HRC.
9. The chisel according to claim 8 , 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.
10. The chisel according to claim 8 , wherein a hardness of a surface at room temperature after heating to 600° C. is 32 HRC or more, and a region including the surface has an impact value of 80 J/cm 2 or more.
11. The chisel according to claim 8 , wherein sulfur (S) is present at 0.001% by mass or more and 0.004% by mass or less.
12. The chisel according to claim 8 , wherein the steel has 3.01% by mass or more and 3.80% by mass or less of chromium (Cr).
13. The chisel according to claim 8 , wherein the steel has 3.36% by mass or more and 3.80% by mass or less of chromium (Cr).
14. The chisel according to claim 8 , wherein the steel has 0.27% by mass or more and 0.40% by mass or less of molybdenum (Mo).
15. The chisel according to claim 8 , having a diameter of at least 160 mm.