Duplex stainless steel pipe
AssigneeNippon Steel Corporation
InventorsSeiya Okada, Yuji Arai, Daisuke Matsuo
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Abstract
The duplex stainless steel pipe according to the present disclosure consists of, by mass %, C: 0.030% or less, Si: 1.00% or less, Mn: 0.10 to 7.00%, P: 0.040% or less, S: 0.0050% or less, Cr: 20.0 to 30.0%, Ni: 4.2 to 10.0%, Mo: 0.5 to 5.0%, Cu: 0.5 to 6.0%, N: less than 0.350%, O: 0.0005 to 0.0100%, and Ca: 0.0005 to 0.0100%, with the balance being Fe and impurities. A microstructure consists of, in volume ratio, ferrite in an amount of 30 to 80% with the balance being austenite. A yield strength is 552 MPa or more. A number density of Ca oxides having an equivalent circular diameter of 2.0 μm or more is 500/100 mm2 or more.
Claims4
A duplex stainless steel pipe consisting of, by mass %,
- C:
- 0.030% or less,
- Si:
- 1.00% or less,
- Mn:
- 0.10 to 7.00%,
- P:
- 0.040% or less,
- S:
- 0.0050% or less,
- Cr:
- 20.0 to 30.0%,
- Ni:
- 4.2 to 10.0%,
- Mo:
- 0.5 to 5.0%,
- Cu:
- 0.5 to 6.0%,
- N:
- less than 0.350%,
- O:
- 0.0005 to 0.0100%,
- Ca:
- 0.0005 to 0.0100%,
- V:
- 0 to 0.200%,
- Nb:
- 0 to 0.100%,
- Al:
- 0 to 0.100%,
- Ta:
- 0 to 0.100%,
- Ti:
- 0 to 0.100%,
- Zr:
- 0 to 0.100%,
- Hf:
- 0 to 0.100%,
- W:
- 0 to 0.200%,
- Co:
- 0 to 0.500%,
- Sn:
- 0 to 0.100%,
- Sb:
- 0 to 0.100%,
- B:
- 0 to 0.100%,
- Mg:
- 0 to 0.1000%, and
- rare earth metal:
- 0 to 0.100%,
- with the balance being Fe and impurities,
- wherein:
- a microstructure consists of, in volume ratio, ferrite in an amount of 30 to 80% with the balance being austenite;
- a yield strength is 552 MPa or more;
- and
- a number density of Ca oxides having an equivalent circular diameter of 2.0 μm or more is 500/100 mm2 or more.
Dependencies are inferred from the claim text.