Steel material suitable for use in sour environment
The steel material according to the present disclosure contains a chemical composition consisting of, in mass %, C: 0.20 to 0.50%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.030% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr: 0.10 to 1.50%, Mo: 0.25 to 1.50%, Ti: 0.002 to 0.050%, N: 0.0100% or less and O: 0.0100% or less, with the balance being Fe and impurities. The steel material contains an amount of dissolved C within a range of 0.010 to 0.050 mass %. The steel material also has a yield strength within a range of 655 to less than 862 MPa, and a yield ratio of the steel material is 85% or more.
1. A steel material having
a chemical composition consisting of, in mass %,
C: 0.20 to 0.50%,
Si: 0.05 to 0.50%,
Mn: 0.05 to 1.00%,
P: 0.030% or less,
S: 0.0100% or less,
Al: 0.005 to 0.100%,
Cr: 0.10 to 1.50%,
Mo: 0.25 to 1.50%,
Ti: 0.002 to 0.050%,
N: 0.0100% or less,
O: 0.0100% or less,
B: 0 to 0.0050%,
V: 0 to 0.30%,
Nb: 0 to 0.100%,
Ca: 0 to 0.0100%,
Mg: 0 to 0.0100%,
Zr: 0 to 0.0100%,
rare earth metal: 0 to 0.0100%,
Co: 0 to 0.45%,
W: 0 to 0.50%,
Ni: 0 to 0.50%,
Cu: 0 to 0.50%, and
with the balance being Fe and impurities,
an amount of dissolved C within a range of 0.010 to 0.050 mass %,
a yield strength within a range of 655 to less than 862 MPa, and
a yield ratio of 85% or more.
2. The steel material according to claim 1 , wherein the chemical composition contains:
B: 0.0001 to 0.0050%.
3. The steel material according to claim 1 , wherein the chemical composition contains one or more types of elements selected from the group consisting of:
V: 0.01 to 0.30%, and
Nb: 0.002 to 0.100%.
4. The steel material according to claim 1 , wherein the chemical composition contains one or more types of elements selected from the group consisting of:
Ca: 0.0001 to 0.0100%,
Mg: 0.0001 to 0.0100%,
Zr: 0.0001 to 0.0100%, and
rare earth metal: 0.0001 to 0.0100%.
5. The steel material according to claim 1 , wherein the chemical composition contains one or more types of elements selected from the group consisting of:
Co: 0.02 to 0.45%, and
W: 0.02 to 0.50%.
6. The steel material according to claim 1 , wherein the chemical composition contains one or more types of elements selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.02 to 0.50%.
7. The steel material according to claim 1 , wherein
the yield strength is within the range of 655 to less than 758 MPa.
8. The steel material according to claim 1 , wherein
the yield strength is within the range of 758 to less than 862 MPa.
9. The steel material according to claim 1 , wherein
the steel material is an oil-well steel pipe.
10. The steel material according to claim 1 , wherein
the steel material is a seamless steel pipe.