公开(公告)号：US20240182997A1

公开(公告)日：2024-06-06

申请号：US18410064

申请日：2024-01-11

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Hiroyuki KAWATA ,  Kunio HAYASHI ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C21D9/46 ,  B32B15/01 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D8/0226 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/60 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/003 ,  C21D2211/005 ,  C21D2211/008 ,  C21D2211/009

Abstract: A hot dip galvanized steel sheet includes a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition, and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 0% to 30%, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, when there are remaining structures, the remaining structures consist of bainite, a concentration of B atoms at prior austenite grain boundaries is 2.0 atm % or more, and an average effective crystal grain size is 7.0 μm or less, and a method for producing the same.

公开(公告)号：US20220064771A1

公开(公告)日：2022-03-03

申请号：US17421317

申请日：2020-02-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Hiroyuki KAWATA ,  Kunio HAYASHI ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C22C38/58 ,  C22C38/02 ,  C22C38/50 ,  C22C38/46 ,  C22C38/48 ,  C22C38/42 ,  C22C38/52 ,  C22C38/00 ,  C22C38/54 ,  C22C38/44 ,  C21D8/02

Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 6% to 30%, bainite: 5% or more, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, a number density of tempered martensite with a circle equivalent diameter of 5.0 μm or more is 20/1000 μm2 or less, and an area ratio of fresh martensite with a circle equivalent diameter of 2.0 μm or more after imparting 5% plastic strain is 10% or less, and a method for producing the same.

公开(公告)号：US20220119908A1

公开(公告)日：2022-04-21

申请号：US17427870

申请日：2020-02-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Hiroyuki KAWATA ,  Kunio HAYASHI ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/60 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23C2/40

Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet and a hot dip galvanized layer on at least one surface of the base metal steel sheet, wherein the base steel sheet has a predetermined chemical composition, and contains, by volume fraction, ferrite: 0% to 50%, retained austenite: 0% to 30%, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, when there are remaining structures, the remaining structures consist of bainite, a concentration of B atoms at prior austenite grain boundaries is 2.0 atm % or more, and an average effective crystal grain size is 7.0 μm or less, and a method for producing the same.

公开(公告)号：US20220127709A1

公开(公告)日：2022-04-28

申请号：US17427680

申请日：2020-02-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Hiroyuki KAWATA ,  Kunio HAYASHI ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C23C2/40 ,  C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/60 ,  C23C2/06 ,  C23C2/28

Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet wherein the base steel sheet has a predetermined chemical composition, and contains ferrite: 50% or less, retained austenite: 30% or less, tempered martensite: 5% or more, fresh martensite: 10% or less, and pearlite and cementite in total: 5% or less, remaining structures consist of bainite, and a number ratio of tempered martensite with a Mn concentration profile satisfying [Mn]b/[Mn]a>1.2 and [Mn]a/[Mn]

公开(公告)号：US20220090248A1

公开(公告)日：2022-03-24

申请号：US17425234

申请日：2020-02-06

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Hiroyuki KAWATA ,  Kunio HAYASHI ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C22C38/58 ,  C22C38/02 ,  C22C38/06 ,  C22C38/00 ,  C22C38/48 ,  C22C38/44 ,  C22C38/52 ,  C22C38/42 ,  C22C38/46 ,  C22C38/50 ,  C22C38/54 ,  C21D8/02 ,  C23C2/40

Abstract: Provided are a hot dip galvanized steel sheet comprising a base steel sheet wherein the base steel sheet has a predetermined composition and contains ferrite: 0% to 50%, retained austenite: 0% to 30%, tempered martensite: 5% or more, fresh martensite: 0% to 10%, and pearlite and cementite in total: 0% to 5%, remaining structures consist of bainite, when defining a region having a hardness of 90% or less of the hardness at a position of ¼ thickness to the base steel sheet side from an interface of the base steel sheet and a hot dip galvanized layer as a “soft layer”, there is a soft layer having a thickness of 10 μm or more at the base steel sheet side from the interface, the soft layer contains tempered martensite, and an increase rate in a thickness direction of an area % of tempered martensite from the interface to the inside of the base steel sheet inside the soft layer is 5.0%/pm or less, and a method for producing the same.

公开(公告)号：US20210230712A1

公开(公告)日：2021-07-29

申请号：US17051110

申请日：2019-04-26

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Kunio HAYASHI ,  Masahiro NAKATA ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C21D9/46 ,  C21D6/00 ,  B32B15/01 ,  C21D1/26 ,  C22C38/38 ,  C22C38/30 ,  C22C38/22 ,  C22C38/16 ,  C22C38/60 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/26 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A zinc-plated steel sheet of an aspect of the present invention includes a steel sheet having a predetermined chemical composition and a zinc-plated layer. In the steel sheet, steel microstructures in a range of ⅛ thickness to ⅜ thickness, having the center at ¼ thickness from a steel sheet surface, include, by vol %, ferrite: 0% to 10%, bainite: 0% to 20%, tempered martensite: 70% or more, fresh martensite: 0% to 10%, retained austenite: 0% to 10%, and pearlite: 0% to 5%. In the zinc-plated steel sheet, the amount of hydrogen emitted when the steel sheet is heated to 200° C. from a room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the steel sheet, the tensile strength is 1470 MPa or more, and no cracking occurs in a U-shape bending test where a stress equivalent to 1000 MPa is applied for 24 hours.

公开(公告)号：US20210155999A1

公开(公告)日：2021-05-27

申请号：US17047663

申请日：2019-04-26

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Kunio HAYASHI ,  Masahiro NAKATA ,  Yuji YAMAGUCHI ,  Satoshi UCHIDA

IPC: C21D9/46 ,  C21D1/26 ,  C21D6/00 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60 ,  B32B15/01

Abstract: A zinc-plated steel sheet of an aspect of the present invention includes a steel sheet having a predetermined chemical composition and a zinc-plated layer. In the steel sheet, steel microstructures in a range of ⅛ thickness to ⅜ thickness, having the center at ¼ thickness from a steel sheet surface, include, by vol %, ferrite: 0% to 10%, bainite: 0% to 30%, tempered martensite: 50% or more, fresh martensite: 0% to 10%, retained austenite: more than 10% and 30% or less, and pearlite: 0% to 5%. In the zinc-plated steel sheet, the amount of hydrogen emitted when the steel sheet is heated to 200° C. from room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the steel sheet, the tensile strength is 1470 MPa or more, and no cracking occurs in a U-shape bending test where a stress equivalent to 1000 MPa is applied for 24 hours.

公开(公告)号：US20210123122A1

公开(公告)日：2021-04-29

申请号：US17041372

申请日：2018-03-30

Applicant: NIPPON STEEL CORPORATION

Inventor： Takafumi YOKOYAMA ,  Kohichi SANO ,  Riki OKAMOTO ,  Hiroyuki KAWATA ,  Eisaku SAKURADA ,  Yuji YAMAGUCHI ,  Kazuki SHIOKAWA ,  Yuichi NAKAHIRA ,  Kohei UEDA ,  Masahiro NAKATA ,  Satoshi UCHIDA

IPC: C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/02 ,  C22C38/00 ,  C22C38/06 ,  C21D9/46 ,  C23C2/06 ,  C23C2/40 ,  C21D8/02 ,  C21D9/00

Abstract: This steel sheet has a predetermined chemical composition, in which a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder includes hard ferrite, in the inside of the steel sheet, a number proportion of the retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, a soft layer having a thickness of 1 to 100 μm from a surface in a sheet thickness direction is present, in ferrite contained in the soft layer, a volume fraction of grains having an aspect ratio of less than 3.0 is 50% or more, the volume fraction of retained austenite in the soft layer is less than 50% of the volume fraction of the retained austenite of the inside of the steel sheet, and a peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 μm and 5.0 μm or less from the surface.

公开(公告)号：US20210054491A1

公开(公告)日：2021-02-25

申请号：US16770003

申请日：2018-12-03

Applicant: NIPPON STEEL CORPORATION ,  NIPPON STEEL HARDFACING CORPORATION

Inventor： Yasushi KURISU ,  Hayato KONNAI ,  Futoshi NISHIMURA ,  Satoshi UCHIDA ,  Atsushi MIGITA ,  Yuuki MISHIMA

IPC: C23C2/06 ,  C23C2/40

Abstract: A hot dip metal plating bath roll preventing flaws in a steel sheet due to a bath roll, realizing stable running at a high speed, and improving the productivity of a plated steel sheet, which hot dip metal plating bath roll having vertical grooves each formed on an outer circumferential surface of the roll and including two first curved parts projecting to the outside of the roll and at least one second curved part arranged between the two first curved part and projecting to the inside of the roll and horizontal grooves each formed on an outer circumferential surface of the roll along a barrel length direction of the roll, a pitch P1 (mm) and depth d1 (mm) of the vertical grooves satisfying 1.0≤P1≤10, 0.2≤d1≤5, and d1≤P1/2, a depth d2 (mm) being 60% to 150% of the depth d1 of the vertical grooves, and a width w2 (mm) of the horizontal grooves being 2 times or more of the depth d2 or 2 times or more of a radius of curvature (mm) of curved surfaces forming bottom parts of the horizontal grooves and 0.7 times or less of a pitch P2 (mm), the pitch P2 (mm) of the horizontal grooves being 1.0≤P2≤10.

公开(公告)号：US20200156349A1

公开(公告)日：2020-05-21

申请号：US16635511

申请日：2017-07-31

Applicant: NIPPON STEEL CORPORATION

Inventor： Atsushi MORISHITA ,  Taihei KANETO ,  Satoshi UCHIDA ,  Tatsuya NAKADA ,  Yuji YAMAGUCHI

IPC: B32B15/01 ,  C22C38/28 ,  C21D9/46 ,  C22C38/38 ,  C21D6/00 ,  C22C38/26 ,  C22C38/02 ,  C22C38/00 ,  C22C38/22 ,  C22C38/08 ,  C22C38/32 ,  C21D8/02 ,  C22C38/16 ,  C22C38/06

Abstract: There is provided a hot-dip galvanized steel sheet with a microstructure in a ⅛ thickness to ⅜ thickness range whose middle is a ¼ thickness from a surface of a base steel sheet, the microstructure contains ferrite phase is 50% or more and 97% or less by volume fraction, and a predetermined phase wherein at an interface between a hot-dip galvanizing layer and the base steel sheet, a Fe—Al alloy layer has an average thickness of 0.1 μm to 2.0 μm, and a difference between a maximum thickness and a minimum thickness in a steel sheet width direction is within 0.5 μm, and in a fine-grain layer directly brought into contact with the Fe—Al alloy layer, the fine-grain has a difference between a maximum thickness and a minimum thickness of the fine-grain layer in the steel sheet width direction is within 2.0 μm.