公开(公告)号：US20230399729A1

公开(公告)日：2023-12-14

申请号：US18032108

申请日：2021-10-13

Applicant: NIPPON STEEL CORPORATION

Inventor： Kohei NAKADA ,  Ryo TABATA ,  Takeshi KAWACHI ,  Takeshi TOYODA

IPC: C22C38/60 ,  C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/34 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

CPC classification number: C22C38/60 ,  C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/34 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  B62D29/007

Abstract: As a burring processed member able to suppress the formation of fatigue cracks in a burring part, one having a structure satisfying the following relations (1) to (3) is disclosed: 3≤Ra≤100 . . . (1), 3.0

公开(公告)号：US20220106655A1

公开(公告)日：2022-04-07

申请号：US17420583

申请日：2020-01-20

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke ITO ,  Takeshi TOYODA

IPC: C21D8/02 ,  C21D9/46 ,  B21C47/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/00 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54

Abstract: To provide a hot-rolled steel sheet comprising by mass %: C: 0.12% or more and 0.25% or less, Si: 0.01% or more and 2.0% or less, Mn: 0.5% or more and 3.0% or less, Al: 0.001% or more and 0.10% or less, and B: 0.0005% or more and 0.0050% or less, and comprising one or both of: Nb: 0.001% or more and 0.020% or less, and Ti: 0.001% or more and 0.20% or less, wherein a metal structure at a position of ¼ thickness from a surface contains more than 90%, in area ratio, of tempered martensite, carbides in the tempered martensite have an average grain size of 10 nm or less, prior austenite grains have an average grain size of less than 40 μm, the prior austenite grains have an aspect ratio of 3.5 or less, and an X-ray random intensity ratio of {112} orientation at a position of ½ thickness from a surface is 4.0 or less, and a method for manufacturing the same.

公开(公告)号：US20220380876A1

公开(公告)日：2022-12-01

申请号：US17760966

申请日：2020-12-08

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke ITO ,  Shohei YABU ,  Takeshi TOYODA

IPC: C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/26 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure at a 1/4 position of a sheet thickness in a sheet thickness direction from a surface, by area ratios, a primary phase is 95.00% to 98.00% of bainite, a secondary phase is 2.00% to 5.00% of tempered martensite, an average grain size of the secondary phase is 1.5 μm or less, a pole density in a (110) orientation is 3.0 or less, an average grain size of an iron-based carbide is 0.100 μm or less, in a microstructure from the surface to a 1/16 position of the sheet thickness in the sheet thickness direction from the surface, a pole density in a (110) orientation is 3.0 or less, and a tensile, strength TS is 980 MPa or more.

公开(公告)号：US20210040589A1

公开(公告)日：2021-02-11

申请号：US17044693

申请日：2019-04-17

Applicant: NIPPON STEEL CORPORATION

Inventor： Takeshi TOYODA ,  Tetsuya HIRASHIMA ,  Riki OKAMOTO

IPC: C22C38/34 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02

Abstract: The hot-rolled steel sheet includes, in % by mass, 0.10% or more and 0.50% or less of C; 0.10% or more and 3.0% or less of Si; 0.5% or more and 3.0% or less of Mn; 0.10% or less of P; 0.010% or less of S; 1.00% or less of Al; 0.010% or less of N; 0% or more and 0.20% or less of Ti; 0% or more and 0.100% or less of Nb; 0% or more and 0.0060% or less of Ca; 0% or more and 0.50% or less of Mo; and 0% or more and 1.00% or less of Cr; with the balance comprising Fe and impurities, and an average grain size of prior austenite in a structure is 0.1 μm or larger and 3.0 μm or smaller, and a sheet crown quantity corresponding to a thickness difference between a width center portion and a portion away, by 10 mm, from a width edge portion in the widthwise direction toward the width center portion is 80 μm or smaller.

公开(公告)号：US20200224294A1

公开(公告)日：2020-07-16

申请号：US16626469

申请日：2018-08-09

Applicant: NIPPON STEEL CORPORATION

Inventor： Tetsuya HIRASHIMA ,  Takeshi TOYODA

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

Abstract: A hot rolled steel sheet according to an aspect of the present invention has a predetermined chemical composition, and a metallographic structure in which martensite is the major structure, wherein an average length of grains in an L direction parallel to a rolling direction is 0.2 μm or more and 5.0 μm or less, an average length of grains in a C direction parallel to a transverse direction is 0.1 μm or more and 5.0 μm or less, the ratio of the average length in the C direction to the average length in the L direction is 0.2 or more and 5.0 or less, and the tensile strength is 1180 MPa or more.

公开(公告)号：US20190390294A1

公开(公告)日：2019-12-26

申请号：US16481765

申请日：2018-02-16

Applicant: NIPPON STEEL CORPORATION

Inventor： Takeshi TOYODA ,  Riki OKAMOTO ,  Natsuko SUGIURA ,  Tetsuya HIRASHIMA

IPC: C21D9/46 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  B21B3/02 ,  B21B45/00

Abstract: A hot rolled steel sheet is provided, which is excellent in collision characteristics, excellent in anisotropy of toughness, and high in strength. The hot rolled steel sheet is characterized by containing, by mass %, C: 0.10% to 0.50%, Si: 0.10% to 3.00%, Mn: 0.5% to 3.0%, P: 0.100% or less, S: 0.010% or less, Al: 1.00% or less, N: 0.010% or less and a balance of Fe and impurities, wherein a metal structure at position of ¼ thickness from surface in L-cross-section of the steel sheet comprises prior austenite grains of average value of aspect ratios of 2.0 or less, average grain size of 0.1 μm to 3.0 μm, and coefficient of variation of a standard deviation of grain size distribution/average grain size of 0.40 or more, and a texture with X-ray diffraction intensity ratio of {001} orientation for random samples of 2.0 or more, and the steel sheet has tensile strength of 1180 MPa or more.

公开(公告)号：US20240401163A1

公开(公告)日：2024-12-05

申请号：US18697364

申请日：2022-10-12

Applicant: NIPPON STEEL CORPORATION

Inventor： Yasuyuki OGISU ,  Takeshi TOYODA

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06

Abstract: This hot-rolled steel sheet has a predetermined chemical composition and a microstructure, in which, in a texture of a surface layer region, pole densities of {001} , {111} , and {112} orientation groups are 2.0 or more, in a texture of an internal region, a pole density of a {110} orientation is 5.0 or less, and a tensile strength is 1,180 MPa or more.

公开(公告)号：US20230029319A1

公开(公告)日：2023-01-26

申请号：US17785301

申请日：2021-02-12

Applicant: NIPPON STEEL CORPORATION

Inventor： Kohei NAKADA ,  Takeshi TOYODA

IPC: C22C38/40 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00

Abstract: Provided is a hot rolled steel sheet having a predetermined chemical composition and a microstructure comprising, by area ratio, pearlite: 90 to 100% and pro-eutectoid ferrite: 0 to 10%, wherein the pearlite has an average lamellar spacing of 0.08 to 0.30 μm, and the percentage of cementite in the pearlite having a major axis length of more than 0.3 μm and an aspect ratio of less than 3.0 is less than 15%.

公开(公告)号：US20220033927A1

公开(公告)日：2022-02-03

申请号：US17296496

申请日：2020-03-02

Applicant: NIPPON STEEL CORPORATION

Inventor： Kohei NAKADA ,  Takeshi TOYODA

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/40

Abstract: Provided is a hot rolled steel sheet comprising a predetermined chemical composition, and a metallic structure comprising, by area ratio, pearlite: 90 to 100%, pseudo pearlite: 0 to 10%, and pro-eutectoid ferrite: 0 to 1%, wherein the pearlite has an average lamellar spacing of 0.20 μm or less, and the pearlite has an average pearlite block size of 20.0 μm or less. Provided is a method for producing a hot rolled steel sheet comprising heating a slab to 1100° C. or more, hot rolling where an exit side temperature of finishing rolling is 820 to 920° C., primary cooling the steel sheet down to an Ae1 point by an average cooling rate of 40 to 80° C./s, then secondary cooling the steel sheet from the Ae1 point down to a coiling temperature by an average cooling rate of less than 20° C./s, and coiling the steel sheet at a coiling temperature of 540 to 700° C.

公开(公告)号：US20230287530A1

公开(公告)日：2023-09-14

申请号：US17918903

申请日：2021-04-15

Applicant: NIPPON STEEL CORPORATION

Inventor： Yukiko KOBAYASHI ,  Jun TAKAHASHI ,  Tatsuo YOKOI ,  Riki OKAMOTO ,  Takeshi TOYODA

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/14

CPC classification number: C21D8/0226 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/14 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength hot-rolled steel sheet: having a predetermined chemical composition; having a mean dislocation density of from 1 × 1014 to 1 × 1016 m-2, and containing at least bainitic ferrite, in which a total area ratio of the bainitic ferrite and ferrite is 70% or more and less than 90%, and in which a total area ratio of martensite and retained austenite is 5% or more and 30% or less, in which, in ferrite crystal grains and in bainitic ferrite crystal grains, a mean number density of TiC precipitates is from 1 × 1017 to 5 × 1018 [precipitates/cm3], in which an amount of Ti present as a TiC precipitate precipitated in a matrix not on dislocations is 30 mass% or more of a total amount of Ti in the steel sheet, and in which a tensile strength is 850 MPa or more.