公开(公告)号：US12264376B2

公开(公告)日：2025-04-01

申请号：US17613316

申请日：2020-04-09

Applicant: JFE Steel Corporation

Inventor： Kazuki Fujimura ,  Kenichiro Eguchi ,  Yusuke Yoshimura ,  Masao Yuga

IPC: C21D9/08 ,  C21D6/00 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/58

Abstract: The invention is intended to provide a duplex stainless steel and a method for manufacturing same. A duplex stainless steel pipe is also provided. A duplex stainless steel of the present invention has a specific composition, and has a microstructure containing an austenitic phase and a ferrite phase. The duplex stainless steel satisfies the following contents for C, Si, Mn, Cr, Mo, Ni, N, Cu, and W in the formula (1) below, and has a yield strength YS of 655 MPa or more, and an absorption energy vE−10 of 40 J or more as measured by a Charpy impact test at a test temperature of −10° C. 0.55[% C]−0.056[% Si]+0.018[% Mn]−0.020[% Cr]−0.087[% Mo]+0.16[% Ni]+0.28[% N]−0.506[% Cu]−0.035[% W]+[% Cu*F]≤0.94  (1)

公开(公告)号：US11193179B2

公开(公告)日：2021-12-07

申请号：US15543813

申请日：2015-12-03

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki Fujimura ,  Yasuhide Ishiguro ,  Seigo Goto

IPC: C21D9/08 ,  C21D6/00 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/50 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D8/10 ,  C22C38/54 ,  C22C38/42 ,  C22C38/00 ,  C22C38/58 ,  C22C38/40 ,  C21D1/25

Abstract: A method of manufacturing a seamless stainless steel pipe for Oil Country Tubular Goods by heating a billet having a specified chemical composition including forming the billet into a seamless steel pipe by applying hot working to the billet, cooling the seamless steel pipe to a room temperature at a cooling rate of air cooling or more, thereafter, performing quenching by heating the seamless steel pipe to a temperature of 850° C. or above, subsequently, cooling the seamless steel pipe to a temperature of 100° C. or below at a cooling rate of air cooling or more, and subsequently, applying tempering to the seamless steel pipe at a temperature of 700° C. or below for a specific holding time.

公开(公告)号：US20190048443A1

公开(公告)日：2019-02-14

申请号：US16078919

申请日：2016-11-18

Applicant: JFE Steel Corporation

Inventor： Mitsuhiro Okatsu ,  Masao Yuga ,  Hiroki Ota ,  Kazuki Fujimura

IPC: C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/08 ,  C21D8/10 ,  C21D6/00 ,  C21D6/02 ,  E21B17/00

Abstract: The steel pipe of the present invention is a low alloy high strength seamless steel pipe for oil country tubular goods including a composition containing, in terms of mass %, C: 0.23 to 0.27%, Si: 0.01 to 0.35%, Mn: 0.45 to 0.70%, P: 0.010% or less, S: 0.001% or less, O: 0.0015% or less, Al: 0.015 to 0.080%, Cu: 0.02 to 0.09%, Cr: 0.8 to 1.5%, Mo: 0.5 to 1.0%, Nb: 0.02 to 0.05%, B: 0.0015 to 0.0030%, Ti: 0.005 to 0.020%, and N: 0.005% or less, and having a value of a ratio of the Ti content to the N content (Ti/N) of 3.0 to 4.0, with the balance being Fe and inevitable impurities, the steel pipe having a ratio of a stress at a strain of 0.7% to a stress at a strain of 0.4% in a stress-strain curve; of 1.02 or less and a yield strength of 655 MPa or more.

公开(公告)号：US20230151469A1

公开(公告)日：2023-05-18

申请号：US17923049

申请日：2021-05-11

Applicant: JFE Steel Corporation

Inventor： Kazuki Fujimura ,  Shunsuke Sasaki ,  Masao Yuga

IPC: C22C38/54 ,  C21D7/10 ,  C22C38/02 ,  C22C38/44 ,  C22C38/00 ,  C22C38/06 ,  C21D9/08

CPC classification number: C22C38/54 ,  C21D7/10 ,  C22C38/02 ,  C22C38/44 ,  C22C38/001 ,  C22C38/06 ,  C21D9/08 ,  C21D2211/001 ,  C21D2211/005

Abstract: A dual-phase stainless steel or dual-phase stainless steel seamless pipe has a certain composition, the dual-phase stainless steel or dual-phase stainless steel seamless pipe having a microstructure containing 20 to 70% austenitic phase and 30 to 80% ferritic phase by volume, the dual-phase stainless steel or dual-phase stainless steel seamless pipe having a yield strength, YS, of 448 MPa or more, and containing oxide inclusions of which oxide inclusions having an average particle diameter of 1 μm or more have a number density of 15/mm2 or less, and at most 50 mass % of the oxide inclusions having an average particle diameter of 1 μm or more are oxide inclusions containing aluminum.

公开(公告)号：US20220228231A1

公开(公告)日：2022-07-21

申请号：US17613316

申请日：2020-04-09

Applicant: JFE Steel Corporation

Inventor： Kazuki Fujimura ,  Kenichiro Eguchi ,  Yusuke Yoshimura ,  Masao Yuga

IPC: C21D9/08 ,  C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D6/00

Abstract: The invention is intended to provide a duplex stainless steel and a method for manufacturing same. A duplex stainless steel pipe is also provided. A duplex stainless steel of the present invention has a specific composition, and has a microstructure containing an austenitic phase and a ferrite phase. The duplex stainless steel satisfies the following contents for C, Si, Mn, Cr, Mo, Ni, N, Cu, and W in the formula (1) below, and has a yield strength YS of 655 MPa or more, and an absorption energy vE−10 of 40 J or more as measured by a Charpy impact test at a test temperature of −10° C. 0.55[% C]−0.056[% Si]+0.018[% Mn]−0.020[% Cr]−0.087[% Mo]+0.16[% Ni]+0.28[% N]−0.506[% Cu]−0.035[% W]+[% Cu*F]≤0.94  (1)

公开(公告)号：US10472690B2

公开(公告)日：2019-11-12

申请号：US15509361

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Masao Yuga ,  Mitsuhiro Okatsu ,  Kazuki Fujimura ,  Yasuhide Ishiguro

IPC: C21D1/22 ,  C21D8/10 ,  C21D9/08 ,  C22C38/00 ,  C22C38/32 ,  C22C38/54 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C21D8/00 ,  C21D1/25

Abstract: Provided is a high-strength seamless steel pipe having the composition which contains, by mass %, 0.20 to 0.50% C, 0.05 to 0.40% Si, 0.3 to 0.9% Mn, 0.015% or less P, 0.005% or less S, 0.005 to 0.1% Al, 0.008% or less N, 0.6 to 1.7% Cr, 0.4 to 1.0% Mo, 0.01 to 0.30% V, 0.01 to 0.06% Nb, 0.0003 to 0.0030% B, and 0.0030% or less O (oxygen). The high-strength seamless steel pipe has the microstructure where a volume fraction of a tempered martensitic phase is 95% or more, and prior austenitic grains have a grain size number of 8.5 or more, and a segregation degree index Ps which is defined by a formula Ps=8.1 (XSi+XMn+XMo)+1.2XP relating to XM which is a ratio between a segregated portion content and an average content is set to less than 65.

公开(公告)号：US12157937B2

公开(公告)日：2024-12-03

申请号：US17296626

申请日：2019-11-01

Applicant: JFE Steel Corporation

Inventor： Shunsuke Sasaki ,  Tatsuro Katsumura ,  Hiroki Ota ,  Kazuki Fujimura ,  Masao Yuga

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

Abstract: Provided herein is a duplex stainless steel seamless pipe and a method for manufacturing the same. The duplex stainless steel seamless pipe has a composition comprising, in mass %, C: 0.005 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.01 to 10.0%, Cr: 20 to 35%, Ni: 1 to 15%, Mo: 0.5 to 6.0%, N: 0.150 to less than 0.400%, and one, two or more selected from Ti: 0.0001 to 0.3%, Al: 0.0001 to 0.3%, V: 0.005 to 1.5%, Nb: 0.005 to less than 1.5%, and the balance being Fe and incidental impurities. The duplex stainless steel seamless pipe contains N, Ti, Al, V, and Nb so as to satisfy the following formula (1). The duplex stainless steel seamless pipe has an axial tensile yield strength of 757 MPa or more, and a ratio of 0.85 to 1.15 as a fraction of axial compressive yield strength to axial tensile yield strength. 0.150>N−(1.58Ti+2.70Al+1.58V+1.44Nb)  (1), wherein N, Ti, Al, V, and Nb represent the content of each element in mass %.

公开(公告)号：US20220018007A1

公开(公告)日：2022-01-20

申请号：US17296626

申请日：2019-11-01

Applicant: JFE Steel Corporation

Inventor： Shunsuke Sasaki ,  Tatsuro Katsumura ,  Hiroki Ota ,  Kazuki Fujimura ,  Masao Yuga

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

Abstract: Provided herein is a duplex stainless steel seamless pipe and a method for manufacturing the same. The duplex stainless steel seamless pipe has a composition comprising, in mass %, C: 0.005 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.01 to 10.0%, Cr: 20 to 35%, Ni: 1 to 15%, Mo: 0.5 to 6.0%, N: 0.150 to less than 0.400%, and one, two or more selected from Ti: 0.0001 to 0.3%, Al: 0.0001 to 0.3%, V: 0.005 to 1.5%, Nb: 0.005 to less than 1.5%, and the balance being Fe and incidental impurities. The duplex stainless steel seamless pipe contains N, Ti, Al, V, and Nb so as to satisfy the following formula (1). The duplex stainless steel seamless pipe has an axial tensile yield strength of 757 MPa or more, and a ratio of 0.85 to 1.15 as a fraction of axial compressive yield strength to axial tensile yield strength. 0.150>N−(1.58Ti+2.70Al+1.58V+1.44Nb) . . .   (1), wherein N, Ti, Al, V, and Nb represent the content of each element in mass %.

公开(公告)号：US10329633B2

公开(公告)日：2019-06-25

申请号：US15311907

申请日：2015-05-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki Fujimura ,  Yasuhide Ishiguro ,  Tetsu Nakahashi ,  Hideo Sato

IPC: C22C38/40 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/42 ,  C21D8/10 ,  C21D9/08 ,  C22C38/58 ,  C21D1/22 ,  C21D8/00 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/54 ,  C21D6/00 ,  C21D9/00

Abstract: A high-strength seamless stainless steel pipe for oil country tubular goods that is excellent in terms of hot workability, sulfide stress cracking resistance, and corrosion resistance, and a method for manufacturing the steel pipe. The steel pipe has a chemical composition containing Cr and Ni so that the relationship Cr/Ni≤5.3 is satisfied. A microstructure of the steel pipe includes mainly a tempered martensite phase. Additionally, a surface layer microstructure of the steel pipe includes a phase which looks white when subjected to etching with a Vilella etching solution, the phase having a thickness in the wall thickness direction from the outer surface of the pipe of 10 μm or more and 100 μm or less and dispersing in the outer surface of the pipe in an amount of 50% or more in terms of area fraction.

公开(公告)号：US20170275715A1

公开(公告)日：2017-09-28

申请号：US15509361

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Masao Yuga ,  Mitsuhiro Okatsu ,  Kazuki Fujimura ,  Yasuhide Ishiguro

IPC: C21D1/22 ,  C21D8/00 ,  C22C38/02 ,  C21D8/10 ,  C21D9/08

Abstract: Provided is a high-strength seamless steel pipe having the composition which contains, by mass %, 0.20 to 0.50% C, 0.05 to 0.40% Si, 0.3 to 0.9% Mn, 0.015% or less P, 0.005% or less S, 0.005 to 0.1% Al, 0.008% or less N, 0.6 to 1.7% Cr, 0.4 to 1.0% Mo, 0.01 to 0.30% V, 0.01 to 0.06% Nb, 0.0003 to 0.0030% B, and 0.0030% or less O (oxygen). The high-strength seamless steel pipe has the microstructure where a volume fraction of a tempered martensitic phase is 95% or more, and prior austenitic grains have a grain size number of 8.5 or more, and a segregation degree index Ps which is defined by a formula Ps=8.1 (XSi+XMn+XMo)+1.2XP relating to XM which is a ratio between a segregated portion content and an average content is set to less than 65.