03-02-2022 дата публикации
Номер: US20220033943A1
Принадлежит:
The seamless steel pipe according to the present disclosure includes a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0050% or less, Al: 0.001 to 0.100%, N: 0.0500% or less, O: 0.050% or less, Ni: 3.00 to 6.50%, Cr: more than 10.00 to 13.40%, Mo: 0.50 to 4.00%, V: 0.01 to 1.00%, Ti: 0.010 to 0.300%, and Co: 0.010 to 0.300%, with the balance being Fe and impurities, and satisfying Formula (1), and a microstructure containing, in volume ratio, 80.0% or more of martensite, wherein a depassivation pH of an inner surface is 3.50 or less. 14-. (canceled)5. A martensitic stainless seamless steel pipe comprising:a chemical composition consisting of, in mass %,C: 0.030% or less,Si: 1.00% or less,Mn: 1.00% or less,P: 0.030% or less,S: 0.0050% or less,Al: 0.001 to 0.100%,N: 0.0500% or less,O: 0.050% or less,Ni: 3.00 to 6.50%,Cr: more than 10.00 to 13.40%,Mo: 0.50 to 4.00%,V: 0.01 to 1.00%,Ti: 0.010 to 0.300%,Co: 0.010 to 0.300%,Ca: 0 to 0.0035%,W: 0 to 1.50%, andwith the balance being Fe and impurities, and satisfying Formula (1), anda microstructure containing, in volume ratio, 80.0% or more of martensite, wherein{'sub': 3', '3, 'claim-text': {'br': None, 'Cr+2.0Mo+0.5Ni+0.5Co≥16.0\u2003\u2003(1)'}, 'an inner surface of the martensitic stainless seamless steel pipe has a depassivation pH of 3.50 or less in an aqueous solution that contains 5 mass % of NaCl and 0.41 g/L of CHCOONa and further contains CHCOOHwhere, a content of a corresponding element (in mass %) is substituted for each symbol of an element in Formula (1).6. The martensitic stainless seamless steel pipe according to claim 5 , whereinthe chemical composition contains:Ca: 0.0010 to 0.0035%.7. The martensitic stainless seamless steel pipe according to claim 5 , whereinthe chemical composition contains:W: 0.10 to 1.50%.8. The martensitic stainless seamless steel pipe according to claim 6 , whereinthe chemical composition contains:W: 0. ...
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