公开(公告)号：US20200024683A1

公开(公告)日：2020-01-23

申请号：US16499181

申请日：2017-03-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Tatsuo YOKOI ,  Nobuo YOSHIKAWA ,  Shigeru YONEMURA ,  Kazuya OOTSUKA

IPC: C21D9/46 ,  C22C38/18 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: A hot rolled steel sheet including a chemical composition consisting of, in mass %, C: 0.07-0.22%, Si: 1.00-3.20%, Mn: 0.80-2.20%, Al: 0.010-1.000%, N≤0.0060%, P≤0.050%, S≤0.005%, Ti: 0-0.150%, Nb: 0-0.100%, V: 0-0.300%, Cu: 0-2.00%, Ni: 0-2.00%, Cr: 0-2.00%, Mo: 0-1.00%, B: 0-0.0100%, Mg: 0-0.0100%, Ca: 0-0.0100%, REM: 0-0.1000%, Zr: 0-1.000%, Co: 0-1.000%, Zn: 0-1.000%, W: 0-1.000%, Sn: 0-0.050%, the balance: Fe and impurities, wherein a metal microstructure includes, in area %, at a position ¼ W or ¾ W from an end face of the steel sheet and ¼ t or ¾ t from a surface, retained austenite: more than 2%-10%, martensite ≤2%, bainite: 10-70%, pearlite ≤2%, the balance: ferrite, an average circle-equivalent diameter of a metallic phase constituted of retained austenite/martensite is 1.0 to 5.0 μm, an average of minimum distances between adjacent metallic phases is 3 μm or more, and a standard deviation of nano hardness is 2.5 GPa or less.

公开(公告)号：US20200032365A1

公开(公告)日：2020-01-30

申请号：US16499800

申请日：2017-03-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Tatsuo YOKOI ,  Nobuo YOSHIKAWA ,  Shigeru YONEMURA ,  Kazuya OOTSUKA

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: A hot rolled steel sheet having a chemical composition consisting of, in mass %, C: 0.020-0.180%, Si: 0.05-1.70%, Mn: 0.50-2.50%, Al: 0.010-1.000%, N: 0.0060%, P≤0.050%, S≤0.005%, Ti: 0-0.150%, Nb: 0-0.100%, V: 0-0.300%, Cu: 0-2.00%, Ni: 0-2.00%, Cr: 0-2.00%, Mo: 0-1.00%, B: 0-0.0100%, Mg: 0-0.0100%, Ca: 0-0.0100%, REM: 0-0.1000%, Zr: 0-1.000%, Co: 0-1.000%, Zn: 0-1.000%, W: 0-1.000%, the balance: Fe and impurities, wherein a metal microstructure includes, in area %, at a position ¼ W or ¾ W from an end face of the steel sheet and ¼ t or ¾ t from a surface, martensite: more than 2%-10%, retained austenite

公开(公告)号：US20230160046A1

公开(公告)日：2023-05-25

申请号：US17909706

申请日：2021-03-26

Applicant: NIPPON STEEL CORPORATION

Inventor： Nobuo YOSHIKAWA ,  Takashi ARAMAKI ,  Tetsuji FUKUZATO ,  Kazuhisa KUSUMI ,  Hisayoshi YATOH ,  Yoshinari YANO

IPC: C22C38/60 ,  C21D7/02 ,  C22C38/32 ,  C22C38/40 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/20 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

CPC classification number: C22C38/60 ,  C21D7/02 ,  C22C38/32 ,  C22C38/40 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/20 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/004 ,  C22C38/002 ,  C22C38/001

Abstract: This steel sheet has a predetermined chemical composition, and, on a surface parallel to a surface at a ¼ position of a sheet thickness in a sheet thickness direction from the surface, with respect to a total area of three types of oxides of MnO, Cr2O3 and Al2O3 having a major axis of more than 1.0 μm, a total area ratio of the MnO and the Cr2O3 is 98.0% or more, and an area ratio of the Al2O3 is 2.0% or less.

公开(公告)号：US20220402015A1

公开(公告)日：2022-12-22

申请号：US17789436

申请日：2021-02-24

Applicant: NIPPON STEEL CORPORATION

Inventor： Soshi FUJITA ,  Yuki SUZUKI ,  Masahiro FUDA ,  Hideaki IRIKAWA ,  Jun MAKI ,  Nobuo YOSHIKAWA ,  Naruhiko NOMURA

IPC: B21D39/03 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C23C2/12 ,  B21D22/02

Abstract: To solve a problem about warpage of a steel sheet due to a difference in temperature raising rate between an overlapped part and a one-sheet part. This manufacturing method includes: a step of heating an overlapped blank; a step of transferring the heated overlapped blank; and a step of performing presswork on the heated overlapped blank by using a die, in which in the heating step, when sheet thicknesses of the first and second steel sheets are set to t1 and t2, respectively, and an average heating rate at a sheet temperature from 20 to 800° C. of a portion with a total sheet thickness (t1+t2) of an overlapped portion, and that of a non-overlapped portion are set to V and v1, respectively, the total sheet thickness (t1+t2) is 2.5 to 5.0 mm, a maximum length L of the overlapped portion is 100 to 1100 mm, an area S1 of the first steel sheet, an area S2 of a portion, of the second steel sheet, which is overlapped with the first steel sheet, and the average heating rates V and v1 satisfy Expressions (1) to (3), and the heating is performed at a heating temperature and for a heating time within a specific range on a plane of coordinates defined by the heating time and the heating temperature.

公开(公告)号：US20210095363A1

公开(公告)日：2021-04-01

申请号：US16499706

申请日：2017-03-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Tatsuo YOKOI ,  Nobuo YOSHIKAWA ,  Shigeru YONEMURA ,  Kazuya OOTSUKA

IPC: C22C38/58 ,  C22C38/44 ,  C22C38/42 ,  C22C38/54 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C21D8/02 ,  C21D8/00 ,  C22C38/00

Abstract: A hot rolled steel sheet having a chemical composition consisting of, in mass %, C: 0.020-0.070%, Si: 0.05-1.70%, Mn: 0.60-2.50%, Al: 0.010-1.000%, N: >0-0.0030%, P≤0.050%, S≤0.005%, Ti: 0.015-0.170%, Nb: 0-0.100%, V: 0-0.300%, Cu: 0-2.00%, Ni: 0-2.00%, Cr: 0-2.00%, Mo: 0-1.00%, B: 0-0.0100%, Mg: 0-0.0100%, Ca: 0-0.0100%, REM: 0-0.1000%, Zr: 0-1.000%, Co: 0-1.000%, Zn: 0-1.000%, W: 0-1.000%, Sn: 0-0.050%, the balance: Fe and impurities, a metal microstructure includes, in area %, ferrite: 5-70%, bainite: 30-95%, retained γ≤2%, martensite≤2%, pearlite≤1%, ferrite+bainite≥95%, a number density of the precipitates in ferrite grains is 1.0×1016−50.0×1016/cm3, an average circle-equivalent diameter of the TiN precipitates in the steel sheet is 1.0-10.0 μm, an average of minimum distances between adjacent TiN precipitates is 10.0 μm or more, and a standard deviation of nano hardness is 1.00 GPa or less.

公开(公告)号：US20200024679A1

公开(公告)日：2020-01-23

申请号：US16485360

申请日：2017-03-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Tatsuo YOKOI ,  Nobuo YOSHIKAWA ,  Shigeru YONEMURA ,  Kazuya OOTSUKA

IPC: C21D1/02 ,  C22C38/00 ,  C22C38/04 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/32 ,  C21D8/00 ,  C21D8/02

Abstract: A hot rolled steel sheet having a chemical composition consisting of, in mass %, C: 0.020-0.070%, Si: 0.05-1.70%, Mn: 0.60-2.50%, Al: 0.005-0.020%, N: >0.0030-0.0060%, P≤0.050%, S≤0.005%, Ti: 0.015-0.170%, Nb: 0-0.100%, V: 0-0.300%, Cu: 0-2.00%, Ni: 0-2.00%, Cr: 0-2.00%, Mo: 0-1.00%, B: 0-0.0100%, Ca: 0-0.0100%, Mg: 0-0.0100%, REM: 0-0.1000%, Zr: 0-1.000%, Co: 0-1.000%, Zn: 0-1.000%, W: 0-1.000%, Sn: 0-0.050%, the balance: Fe and impurities, wherein Ca+Mg+REM≥0.0005, a metal microstructure includes, in area %, ferrite: 5-70%, bainite: 30-95%, retained γ≤2%, martensite ≤2%, pearlite ≤1%, ferrite+bainite≥95%, a number density of the precipitates in ferrite grains is 1.0×1016-50.0×1016/cm3, an average circle-equivalent diameter of the TiN precipitates in the steel sheet is 1.0-10.0 μm, an average of minimum distances between adjacent TiN precipitates is 10.0 μm or more, and a standard deviation of nano hardness is 1.00 GPa or less.