Hot-working steel excellent in machinability and impact value
View Patent ↗Provided is a hot-working steel excellent in machinability and impact value comprising, in mass %, C: 0.06 to 0.85%, Si: 0.01 to 1.5%, Mn: 0.05 to 2.0%, P: 0.005 to 0.2%, S: 0.001 to 0.35%, and Al: 0.06 to 1.0% and N: 0.016% or less, in contents satisfying Al×N×10 5 ≦96, and a balance of Fe and unavoidable impurities, total volume of AlN precipitates of a circle-equivalent diameter exceeding 200 nm accounting for 20% or less of total volume of all AlN precipitates.
1. A hot-worked steel comprising a composition consisting of, in mass %,
C: 0.23 to 0.85%,
Si: 0.01 to 1.5%,
Mn: 0.05 to 2.0%,
P: 0.005 to 0.2%,
S: 0.020 to 0.15%,
Al: 0.110 to 1.0%,
N: 0.016% or less,
and optionally one or more elements in the following ranges:
Ca: 0.0003 to 0.0015%,
Ti: 0.001 to 0.01%,
Nb: 0.005 to 0.2%,
W: 0.01 to 1.0%,
V: 0.01 to 1.0%,
Cr: 0.01 to 2.0%,
Mo: 0.01 to 1.0%,
Ni: 0.05 to 2.0%,
Cu: 0.01 to 2.0%,
Mg: 0.0001 to 0.0040%,
Zr: 0.0003 to 0.01%,
REMs: 0.0001 to 0.015%,
Sn: 0.005 to 2.0%,
Zn: 0.0005 to 0.5%,
B: 0.0005 to 0.015%,
Te: 0.0003 to 0.2%,
Bi: 0.005 to 0.5%, and
Pb: 0.005 to 0.5%, and
in contents satisfying 37≦Al×N×10 5 ≦96, and
a balance of Fe and unavoidable impurities,
total volume of MN precipitates of a circle-equivalent diameter exceeding 200 nm accounting for 20% or less of total volume of all AlN precipitates.
2. A hot-worked steel according to claim 1 , wherein one or more of the optional elements are included in the composition, wherein the elements are selected from the group consisting of
Ca: 0.0003 to 0.0015%,
Ti: 0.001 to 0.01%,
Nb: 0.005 to 0.2%,
W: 0.01 to 1.0%,
V: 0.01 to 1.0%,
Cr: 0.01 to 2.0%,
Mo: 0.01 to 1.0%,
Ni: 0.05 to 2.0%,
Cu: 0.01 to 2.0%,
Mg: 0.0001 to 0.0040%,
Zr: 0.0003 to 0.01%, and
REMs: 0.0001 to 0.015%.
3. A hot-worked steel according to claim 1 or 2 , wherein one or more of the optional elements are included in the composition, wherein the elements are selected from the group consisting of
Sn: 0.005 to 2.0%,
Zn: 0.0005 to 0.5%,
B: 0.0005 to 0.015%,
Te: 0.0003 to 0.2%,
Bi: 0.005 to 0.5%, and
Pb: 0.005 to 0.5%.
4. A hot-worked steel according to claim 1 or 2 , wherein the content of C is 0.30 to 0.85 mass %.
5. A hot-worked steel according to claim 3 , wherein the content of C is 0.30 to 0.85 mass %.
6. A hot-worked steel comprising, in mass %,
C: 0.23 to 0.85%,
Si: 0.01 to 1.5%,
Mn: 0.05 to 2.0%,
P: 0.005 to 0.2%,
S: 0.020 to 0.15%,
Al: 0.110 to 1.0%,
N: 0.016% or less,
and optionally one or more elements in the following ranges:
Ti: 0.001 to 0.01%, and
Zr: 0.0003 to 0.01%,
wherein the steel does not contain Sb, and
in contents satisfying 37≦Al×N×10 5 ≦96, and
a balance of Fe and unavoidable impurities,
total volume of MN precipitates of a circle-equivalent diameter exceeding 200 nm accounting for 20% or less of total volume of all AlN precipitates.
7. A hot-worked steel according to claim 6 , further comprising, in mass %, one or more elements selected from the group consisting of
Ca: 0.0003 to 0.0015%,
Ti: 0.001 to 0.01%,
Nb: 0.005 to 0.2%,
W: 0.01 to 1.0%,
V: 0.01 to 1.0%,
Cr: 0.01 to 2.0%,
Mo: 0.01 to 1.0%,
Ni: 0.05 to 2.0%,
Cu: 0.01 to 2.0%,
Mg: 0.0001 to 0.0040%,
Zr: 0.0003 to 0.01%, and
REMs: 0.0001 to 0.015%.
8. A hot-worked steel according to claim 6 or 7 , further comprising, in mass %, one or more elements selected from the group consisting of
Sn: 0.005 to 2.0%,
Zn: 0.0005 to 0.5%,
B: 0.0005 to 0.015%,
Te: 0.0003 to 0.2%,
Bi: 0.005 to 0.5%, and
Pb: 0.005 to 0.5%.
9. A hot-worked steel according to claim 6 or 7 , wherein the content of C is 0.30 to 0.85 mass %.
10. A hot-worked steel according to claim 8 , wherein the content of C is 0.30 to 0.85 mass %.