公开(公告)号：US20240218492A1

公开(公告)日：2024-07-04

申请号：US18557049

申请日：2021-06-07

Applicant: NIPPON STEEL CORPORATION

Inventor： Yusaku TOMIO ,  Yukinobu NAGATA ,  Shinya SAKAMOTO ,  Takuya HARA

IPC: C22C38/54 ,  C21D6/00 ,  C21D8/10 ,  C21D9/08 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50

CPC classification number: C22C38/54 ,  C21D6/002 ,  C21D6/005 ,  C21D8/105 ,  C21D9/085 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50

Abstract: An ERW steel pipe for a mechanical structural part, the pipe including a straight pipe portion includes a base metal portion and an ERW portion, wherein the base metal portion has a chemical composition including, in terms of % by mass: 0.30 to 0.38% of C, 0.05 to 0.40% of Si, 0.50 to 2.00% of Mn, 0.010 to 0.060% of Al, 0.005 to 0.050% of Ti, and 0.0003 to 0.0050% of B, wherein a microstructure of a wall thickness central portion of the base metal portion is tempered martensite, wherein, a de-C layer in which a concentration of C is 90% or less with respect to the concentration of C in the chemical composition has a thickness of less than 0.20 mm, and a de-B layer in which a concentration of B is 90% or less with respect to the concentration of B in the chemical composition has a thickness of less than 0.10 mm, at each of inner and outer surface sides of the base metal portion, and wherein each of a Vickers hardness at a position at a depth of 0.5 mm from each of the inner and outer surface sides is 420 Hv or more and less than 510 Hv.

公开(公告)号：US20210269904A1

公开(公告)日：2021-09-02

申请号：US17253222

申请日：2019-07-09

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke MATSUO ,  Yusaku TOMIO

IPC: C22C38/50 ,  C22C38/48 ,  C22C38/02 ,  C22C38/04 ,  C22C38/42 ,  C22C38/44 ,  C22C38/06 ,  C22C38/00 ,  C21D9/08 ,  C21D8/06 ,  C21D8/00

Abstract: The chemical composition of the seamless steel pipe contains Cr 15.00 to 18.00% in mass % and satisfies Formulae (1) and (2). Furthermore, in the microstructure, (I) a total volume ratio of ferrite and martensite is 80% or more, with the balance being retained austenite of a volume ratio of 20% or less, (II) the number of intersections NTL in the L-direction observation field of view is 38 or more and NTL/NL is 1.80 or more, and further (III) the number of intersections NTC in the C-direction observation field of view is 30 or more and NTC/NC is 1.70 or more. 156Al+18Ti+12Nb+11Mn+5V+328.125N+243.75C+12.5S≤12.5  (1) Ca/S≥≥4.0  (2)

公开(公告)号：US20200332378A1

公开(公告)日：2020-10-22

申请号：US16759798

申请日：2018-11-14

Applicant: NIPPON STEEL CORPORATION

Inventor： Masayuki SAGARA ,  Yusaku TOMIO ,  Takahiro OSUKI ,  Yusuke UGAWA

IPC: C21D8/00 ,  C22C38/54 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/04 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D6/00

Abstract: A duplex stainless steel with occurrence of pitting suppressed is provided. A duplex stainless steel according to the present disclosure has a chemical composition consisting of, in mass %, Cr: more than 27.00% to 29.00%, Mo: 2.50 to 3.50%, Ni: 5.00 to 8.00%, W: 4.00 to 6.00%, Cu: 0.01 to less than 0.10%, N: more than 0.400% to 0.600%, C: 0.030% or less, Si: 1.00% or less, Mn 1.00% or less, sol.Al: 0.040% or less, V: 0.50% or less, O: 0.010% or less, P: 0.030% or less, and S: 0.020% or less with the balance being Fe and impurities and satisfying Formula (1), a microstructure consisting of 35 to 65 volume % of ferrite phase with the balance being the austenite phase, and the area fraction of Cu precipitated in the ferrite phase is 0.5% or less. Cr+4.0×Mo+2.0×W+20×N−5×ln(Cu)≥65.2  (1)

公开(公告)号：US20230175107A1

公开(公告)日：2023-06-08

申请号：US17906664

申请日：2020-04-01

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke MATSUO ,  Yusaku TOMIO

IPC: C22C38/54 ,  C22C38/00 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C21D9/08

CPC classification number: C22C38/54 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C21D9/08

Abstract: The steel material of the present disclosure includes a chemical composition consisting of, in mass %, C: 0.035% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0050% or less, sol. Al: 0.005 to 0.100%, N: 0.001 to 0.020%, Ni: 5.00 to 7.00%, Cr: 10.00 to 14.00%, Cu: 1.50 to 3.50%, Mo: 1.00 to 4.00%, V: 0.01 to 1.00%, Ti: 0.02 to 0.30%, Co: 0.01 to 0.50%, Ca: 0.0003 to 0.0030%, O: 0.0050% or less, W: 0 to 1.50%, Nb: 0 to 0.50%, B: 0 to 0.0050%, Mg: 0 to 0.0050%, and rare earth metals (REM): 0 to 0.020%, with the balance being Fe and impurities, in which a total number density of Mn sulfide having an equivalent circular diameter of 1.0 μm or more and Ca sulfide having an equivalent circular diameter of 2.0 μm or more is 0.50 pieces/mm2 or less.

公开(公告)号：US20210238705A1

公开(公告)日：2021-08-05

申请号：US16973231

申请日：2019-09-26

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke MATSUO ,  Yusaku TOMIO

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

Abstract: The martensitic stainless steel material has a chemical composition, which contains: in mass %, C: 0.030% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.005% or less, Al: 0.010 to 0.100%, N: 0.0010 to 0.0100%, Ni: 5.00 to 6.50%, Cr: 10.00 to 13.40%, Cu: 1.80 to 3.50%, Mo: 1.00 to 4.00%, V: 0.01 to 1.00%, Ti: 0.050 to 0.300%, Co: 0.300% or less, Ca: 0.0006 to 0.0030%, and O: 0.0050% or less, and satisfies Formulae (1) and (2) in the description. An area of each intermetallic compound and each Cr oxide in the steel material is 5.0 μm2 or less, a total area fraction of intermetallic compounds and Cr oxides is 3.0% or less, and a maximum circle-equivalent diameter of Ca oxide is 9.5 μm or less.

公开(公告)号：US20230392241A1

公开(公告)日：2023-12-07

申请号：US18245773

申请日：2021-10-07

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke MATSUO ,  Yusaku TOMIO

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

CPC classification number: C22C38/44 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  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 ,  C21D2211/008

Abstract: A martensitic stainless steel material according to the present disclosure contains, in mass %, C: 0.030% or less, Ni: 5.05 to 7.50%, Cr: 10.00 to 14.00%, and Mo: 1.50 to 3.50%, and has a yield strength of 758 MPa or more, and 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, a degree of Cr segregation ΔCr defined by Formula (1) and a degree of Mo segregation ΔMo defined by Formula (2) satisfy Formula (3):


ΔCr=([Cr*]max−[Cr*]min)/[Cr*]ave  (1)



ΔMo=([Mo*]max−[Mo*]min)/[Mo*]ave  (2)



ΔCr+ΔMo≤0.59  (3).

公开(公告)号：US20230114537A1

公开(公告)日：2023-04-13

申请号：US17907308

申请日：2021-04-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Kosei KATO ,  Yusaku TOMIO

IPC: C22C38/58 ,  C22C38/02 ,  C21D9/08 ,  C21D8/10 ,  C22C38/06 ,  C22C38/44 ,  C22C38/46

Abstract: The martensitic stainless steel seamless pipe according to the present disclosure has a chemical composition containing, in mass %, C: 0.001 to 0.050%, Si: 0.05 to 1.00%, Mn: 0.05 to 2.00%, P: 0.030% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, N: 0.020% or less, Ni: 1.00 to 9.00%, Cr: 8.00 to 16.00%, Cu: 3.50% or less, Mo: 1.00 to 5.00%, W: 0.01 to 0.30%, V: 0.010 to 1.500%, and Co: 0.001 to 0.500%, and also containing one or more elements selected from the group consisting of Ca, Mg, B, and rare earth metal, with the balance being Fe and impurities, and has a yield strength of 655 MPa or more.

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)

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：US20220145438A1

公开(公告)日：2022-05-12

申请号：US17597745

申请日：2020-08-18

Applicant: NIPPON STEEL CORPORATION

Inventor： Mikiko NOGUCHI ,  Yusaku TOMIO ,  Toshio MOCHIZUKI

IPC: C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00

Abstract: The duplex stainless steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 0.20 to 1.00%, Mn: 0.50 to 7.00%, P: 0.040% or less, S: 0.0100% or less, Al: 0.100% or less, Ni: 4.20 to 9.00%, Cr: 20.00 to 28.00%, Mo: 0.50 to 2.00%, Cu: 1.90 to 4.00%, N: 0.150 to 0.350%, V: 0.01 to 1.50%, and one or more types of element selected from the group consisting of Ca: 0.0001 to 0.0200% and Mg: 0.0001 to 0.0200%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2) described in the description, a microstructure consisting of 35.0 to less than 50.0% of ferrite in volume ratio and austenite as the balance, and a yield strength of 550 MPa or more.