公开(公告)号：US20240401722A1

公开(公告)日：2024-12-05

申请号：US18693251

申请日：2022-09-29

Applicant: NIPPON STEEL CORPORATION

Inventor： Toshiya NISHIMURA ,  Daisuke MATSUO ,  Kyohei KANKI

IPC: F16L9/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/50 ,  C22C38/52

Abstract: A martensitic stainless steel pipe according to the present disclosure consists of, in mass %, C: less than 0.030%, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0010 to 0.0050%, Cr: 10.00 to 14.00%, Ni: 5.00 to 7.50%, Mo: 1.10 to 3.50%, Cu: 1.00 to 3.50%, Al: 0.005 to 0.050%, N: 0.0030 to 0.0500%, V: 0.01 to 0.30%, Ti: 0.020 to 0.150%, Co: 0.01 to 0.50%, Ca: 0.0010 to 0.0050%, and the balance: Fe and impurities. The yield strength is 758 MPa or more. A number density of Ca sulfides having an equivalent circular diameter of 1.0 μm or more is 3/mm2 or more.

公开(公告)号：US20250146112A1

公开(公告)日：2025-05-08

申请号：US18837961

申请日：2023-05-12

Applicant: NIPPON STEEL CORPORATION

Inventor： Kyohei KANKI ,  Daisuke MATSUO ,  Yuji ARAI

IPC: C22C38/54 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52

Abstract: A martensitic stainless steel material having high strength, and having excellent corrosion resistance in a corrosive environment in which SOx or NOx is mixed is provided. The martensitic stainless steel material according to the present disclosure satisfies a chemical composition described herein, and satisfies Formula (1). The yield strength is 862 MPa or more. In the martensitic stainless steel material, a number ratio of Mg oxides having an equivalent circular diameter of 2.0 μm or more with respect to Ca oxides having an equivalent circular diameter of 2.0 μm or more, Ca sulfides having an equivalent circular diameter of 2.0 μm or more, and the Mg oxides having an equivalent circular diameter of 2.0 μm or more is 45.0% or more. 0.001 ≤ Ca + Mg ≤ 0.005 ( 1 ) Where, a content of a corresponding element in percent by mass is substituted for each symbol of an element in Formula (1).

公开(公告)号：US20240401178A1

公开(公告)日：2024-12-05

申请号：US18699650

申请日：2022-10-25

Applicant: NIPPON STEEL CORPORATION

Inventor： Kyohei KANKI ,  Daisuke MATSUO ,  Hideki TAKABE ,  Toshiya NISHIMURA

IPC: C22C38/54 ,  C21D1/18 ,  C21D6/00 ,  C21D8/06 ,  C21D9/52 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/60

Abstract: A martensitic stainless steel round bar of the present disclosure contains, in mass %, C: 0.030% or less, Cr: 10.00 to 14.00%, Ni: 5.00 to 7.50%, Mo: 1.50 to 4.00%, Cu: 1.00 to 3.50%, W: 0.01 to 2.00%, and Co: 0.010 to 0.500%, and has a yield strength of 862 MPa or more. When, at the center position of a cross section perpendicular to the axial direction of the martensitic stainless steel round bar, a dissolved Mo concentration is defined as [Mo]C, a dissolved W concentration is defined as [W]C, an Mo concentration in a residue obtained by constant-current electrolysis is defined as [Mo]R, and a W concentration in the residue is defined as [W]R, Formula (1) and Formula (2) are satisfied. F ⁢ 1 = [ Mo ] C + 0.5 [ W ] C ≥ 2.45 ( 1 ) F ⁢ 2 = F ⁢ 1 / ( [ Mo ] R + [ W ] R ) ≥ 13. ( 2 )

公开(公告)号：US20210317556A1

公开(公告)日：2021-10-14

申请号：US17277794

申请日：2019-10-01

Applicant: NIPPON STEEL CORPORATION

Inventor： Kyohei KANKI ,  Masayuki SAGARA ,  Yusaku TOMIO ,  Daisuke MATSUO

IPC: C22C38/52 ,  C22C38/50 ,  C22C38/46 ,  C22C38/48 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/14 ,  C21D8/10 ,  C21D6/00

Abstract: 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: 5.00 to 6.50%, Cr: more than 10.00 to 13.40%, Cu: more than 1.50 to 3.50%, Mo: 1.00 to 4.00%, V: 0.01 to 1.00%, Ti: 0.050 to 0.300%, and Co: 0.010 to 0.300%, with the balance being Fe and impurities, and satisfying Formula (1), wherein a depassivation pH of an inner surface is 3.00 or less. Cr+2.0Mo+0.5Ni+2.0Cu+0.5Co≥20.0  (1)

公开(公告)号：US20240417835A1

公开(公告)日：2024-12-19

申请号：US18702426

申请日：2022-10-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Kyohei KANKI ,  Hideki TAKABE ,  Katsuhiro NISHIHARA ,  Takafumi AMINO

IPC: C22C38/44 ,  C21D1/18 ,  C21D8/10 ,  C21D9/08 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/46 ,  C22C38/50 ,  C22C38/52

Abstract: A martensitic stainless steel seamless pipe according to the present disclosure has a chemical composition and the microstructure described in the description, and a yield strength of 862 MPa or more. An observation field of view region which is 1.0 μm long in each of L direction and T direction and which includes an inner surface is composed of an inner surface vicinity region, an interior region that is below contact with the inner surface vicinity region, and a hollow region. An inner surface Cu occupancy OScu which is defined as the numerical proportion of sections in which a Cu concentration is more than 2.0% in the inner surface vicinity region, and an interior Cu occupancy OIcu which is defined as the numerical proportion of sections in which the Cu concentration is more than 2.0% in the interior region satisfy Formula (2). OS Cu / OI Cu ≥ 1.2 ( 2 )

公开(公告)号：US20220033943A1

公开(公告)日：2022-02-03

申请号：US17278742

申请日：2019-10-01

Applicant: NIPPON STEEL CORPORATION

Inventor： Kyohei KANKI ,  Masayuki SAGARA ,  Yusaku TOMIO

IPC: C22C38/52 ,  C22C38/50 ,  C22C38/46 ,  C22C38/44 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/10 ,  C21D6/00 ,  C21D9/08 ,  E21B17/00

Abstract: 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. Cr+2.0Mo+0.5Ni+0.5Co≥16.0  (1)