公开(公告)号：US20200157650A1

公开(公告)日：2020-05-21

申请号：US16774245

申请日：2020-01-28

申请人： NIPPON STEEL CORPORATION

发明人： Tatsuo Yokoi ,  Eisaku Sakurada ,  Natsuko Sugiura ,  Kiyoyuki Fukui

IPC分类号： C21D9/46 ,  C22C38/00 ,  C22C38/58 ,  C21D6/02 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/30 ,  C23C2/06 ,  C23C2/28

摘要： A hot-rolled steel sheet has a chemical composition that contains, in mass %, C, Si, Mn, P, S, Al, N and Ti, and that satisfies Formula (1); and a microstructure containing bainite and ferrite. In the interior of the steel sheet an average value of pole densities of an orientation group {100} to {223} is 4 or less, and a pole density of a {332} crystal orientation is 4.8 or less. In an outer layer of the steel sheet, a pole density of a {110} crystal orientation is 2.5 or more. Furthermore, among Ti carbo-nitrides in the steel sheet, the number density of fine Ti carbo-nitrides having a particle diameter of 10 nm or less is 1.0×1017 per cm3 or less, and a bake hardening amount is 15 MPa or more. [Ti]−48/14×[N]−48/32×[S]≥0  (1)

公开(公告)号：US11236412B2

公开(公告)日：2022-02-01

申请号：US16315120

申请日：2017-08-04

申请人： NIPPON STEEL CORPORATION

发明人： Kohichi Sano ,  Makoto Uno ,  Ryoichi Nishiyama ,  Yuji Yamaguchi ,  Natsuko Sugiura ,  Masahiro Nakata

IPC分类号： C21D9/46 ,  C22C38/38 ,  C22C38/00 ,  C22C38/58 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C23C2/06 ,  C23C2/40 ,  C21D8/02

摘要： A steel sheet has a specific chemical composition and has a structure represented by, by area ratio, ferrite: 30 to 95%, and bainite: 5 to 70%. When a region that is surrounded by a grain boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 μm or more is defined as a crystal grain, the proportion of crystal grains each having an intragranular misorientation of 5 to 14° to all crystal grains is 20 to 100% by area ratio. An average aspect ratio of ellipses equivalent to the crystal grains is 5 or less. An average distribution density of the total of Ti-based carbides and Nb-based carbides each having a grain size of 20 nm or more on ferrite grain boundaries is 10 carbides/μm or less.

公开(公告)号：US11274355B2

公开(公告)日：2022-03-15

申请号：US16481765

申请日：2018-02-16

申请人： NIPPON STEEL CORPORATION

发明人： Takeshi Toyoda ,  Riki Okamoto ,  Natsuko Sugiura ,  Tetsuya Hirashima

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

摘要： 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.