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：US20250109467A1

公开(公告)日：2025-04-03

申请号：US18711674

申请日：2022-12-22

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke ITO ,  Akifumi SAKAKIBARA ,  Teruki HAYASHIDA ,  Tatsuo YOKOI ,  Kazuhisa KUSUMI

IPC: C22C38/58 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/28 ,  C22C38/38 ,  C22C38/42 ,  C22C38/50 ,  C22C38/54

Abstract: A hot-rolled steel sheet has a predetermined chemical composition, a microstructure at a location of ¼ of a sheet thickness and at a location of 100 μm from a surface comprising, in area %, one or more of martensite and tempered martensite: 95% or more in total, and ferrite, bainite and pearlite: 5% or less in total, and an average dislocation density at the location of 100 μm from the surface is 1.2 times or more of an average dislocation density at the location of ¼ of the sheet thickness.

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：US20230357908A1

公开(公告)日：2023-11-09

申请号：US18027800

申请日：2022-01-07

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke ITO ,  Akifumi SAKAKIBARA ,  Teruki HAYASHIDA ,  Tatsuo YOKOI

IPC: C22C38/58 ,  C22C38/42 ,  C22C38/54 ,  C22C38/50 ,  C22C38/32 ,  C22C38/28 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D9/46 ,  C21D6/00 ,  C21D1/18

CPC classification number: C22C38/58 ,  C22C38/42 ,  C22C38/54 ,  C22C38/50 ,  C22C38/32 ,  C22C38/28 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C21D9/46 ,  C21D6/002 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D1/18 ,  C21D2211/008

Abstract: In a hot-rolled steel sheet, a microstructure contains, in area ratio, at a location at ¼ a sheet thickness, a total amount of 90% or more of one or more of martensite and tempered martensite and a total amount of 10% or less of one or more of ferrite, bainite, and pearlite, at a location of 200 μm from the surface, a total amount of 70% or more and less than 90% of one or more of martensite and tempered martensite and a total amount of more than 10% and 30% or less of one or more of ferrite, bainite, and pearlite.

公开(公告)号：US20220372588A1

公开(公告)日：2022-11-24

申请号：US17767229

申请日：2020-12-08

Applicant: NIPPON STEEL CORPORATION

Inventor： Daisuke ITO ,  Shohei YABU ,  Takeshi TOYODA

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/28 ,  C22C38/32

Abstract: This hot-rolled steel sheet has a predetermined chemical composition, in a microstructure at a ¼ position of a sheet thickness in a sheet thickness direction from a surface, a primary phase is bainite, a secondary phase is martensite or a martensite-austenite mixed phase, an average grain size of the secondary phase is 1.5 μm or less, an average grain size of particles having grain diameters that are largest 10% or less out of all particles in the secondary phase is 2.5 μm or less, a pole density in a (110) orientation is 3.0 or less, and, 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.