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：US20240401177A1

公开(公告)日：2024-12-05

申请号：US18691200

申请日：2022-10-04

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke MATSUO ,  Yuji ARAI

IPC: C22C38/54 ,  C21D9/08 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/50 ,  C22C38/52

Abstract: A duplex stainless steel material that has excellent general corrosion resistance and pitting resistance in a supercritical corrosive environment in which SOX gas and O2 gas are contained in a supercritical CO2 gas is provided. A duplex stainless steel material of the present disclosure has the chemical composition described in the description, and in the duplex stainless steel material, on a precondition that the content of each element is within a range described in the description, Fn defined by Formula (1) is 57.0 or more, and a total number per 1 mm2 of Mn sulfides having an equivalent circular diameter of 1.0 μm or more and Ca sulfides having an equivalent circular diameter of 2.0 μm or more is 0.50/mm2 or less. Fn = Cr + 3.3 ( M ⁢ o + 0 . 5 ⁢ W ) + 1 ⁢ 6 ⁢ N + 2 ⁢ N ⁢ i + C ⁢ u + 2 ⁢ C ⁢ o + 10 ⁢ Sn ( 1 ) Where, the content in mass % of a corresponding element is substituted for each symbol of an element in Formula (1).

公开(公告)号：US20230366071A1

公开(公告)日：2023-11-16

申请号：US18245564

申请日：2021-10-07

Applicant: NIPPON STEEL CORPORATION

Inventor： Toshiya NISHIMURA ,  Daisuke MATSUO

IPC: C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/08 ,  C21D8/10 ,  C21D6/00

CPC classification number: C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/005 ,  C22C38/004 ,  C22C38/002 ,  C22C38/001 ,  C21D9/085 ,  C21D8/105 ,  C21D6/004 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008

Abstract: A martensitic stainless steel material contains, in mass %, C: 0.030% or less, Ni: 5.00 to 7.00%, Cr: 10.00 to 14.00%, and Cu: more than 1.00 to 3.50%. On two line segments LS of 1000 μm extending in a wall thickness direction with arbitrary two points as a center located at positions at a depth of 2 mm from the inner surface, respectively, a degree of Cr segregation ΔCr defined by Formula (1) described in the description, a degree of Mo segregation ΔMo defined by Formula (2) described in the description, and a degree of Cu segregation ΔCu defined by Formula (3) described in the description satisfy Formula (4):


ΔCr+ΔMo+ΔCu≤A  (4)



where, when the yield strength is 758 to less than 862 MPa, A in Formula (4) is 0.70, and when the yield strength is 862 MPa or more, A in Formula (4) is 0.50.

公开(公告)号：US20230109773A1

公开(公告)日：2023-04-13

申请号：US17907304

申请日：2021-04-13

Applicant: NIPPON STEEL CORPORATION

Inventor： Yusaku TOMIO ,  Daisuke MATSUO

IPC: C22C38/58 ,  C22C38/00 ,  C22C38/06 ,  C22C38/42 ,  C22C38/52 ,  C22C38/44 ,  C22C38/02 ,  C21D9/08

Abstract: The martensitic stainless steel material according to the present disclosure consists of C: less than 0.030%, Si: 1.00% or less, Mn: 0.05 to 2.00%, Cr: 11.50 to 14.00%, Ni: 5.00 to 7.50%, Mo: 1.10 to 3.50%, Cu: 0.50 to 3.50%, Co: 0.01 to 0.30%, Al: 0.001 to 0.100%, N: 0.001 to 0.100%, and the balance: Fe and impurities. The microstructure is composed of retained austenite in an amount of 0 to 15 vol%, and ferrite in an amount of 0 to 10 vol%, with the balance being martensite. The yield strength is 862 MPa or more, and a number density of Cu precipitates is 3.0 x 1021 to 50.0 x 1021 /m3.

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)