公开(公告)号：US20200024706A1

公开(公告)日：2020-01-23

申请号：US16334950

申请日：2017-01-30

Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION

Inventor： Katsuya NAKANO ,  Kunio HAYASHI ,  Yuri TODA ,  Eisaku SAKURADA ,  Akihiro UENISHI

IPC: C22C38/04 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/54 ,  C23C2/04

Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 30% to 50%, granular bainite: 5% to 20%, martensite: 30% to 55%, bainite: less than 35%, and retained austenite and pearlite: 10% or less in total. Preferably, of the steel sheet, a tensile strength is 1180 MPa or more, elongation is 10% or more, and a hole expansion value is 20% or more. Further preferably, a VDA bending angle in the case where a thickness is set to t (mm) is “7.69t2−38.4t+109” or more.

公开(公告)号：US20190249282A1

公开(公告)日：2019-08-15

申请号：US16335216

申请日：2017-01-31

Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION

Inventor： Katsuya NAKANO ,  Kunio HAYASHI ,  Yuri TODA ,  Eisaku SAKURADA ,  Akihiro UENISHI

IPC: C22C38/58 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/04 ,  C22C38/22 ,  C22C38/20 ,  C22C38/26 ,  C22C38/24 ,  C22C38/28 ,  C22C38/32 ,  C23C2/06 ,  C23C2/40

CPC classification number: C22C38/58 ,  C21D9/46 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C23C2/06 ,  C23C2/40

Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 50% to 95%, granular bainite: 5% to 48%, tempered martensite: 2% to 30%, upper bainite, lower bainite, fresh martensite, retained austenite, and pearlite: 5% or less in total, and the product of the area fraction of the tempered martensite and a Vickers hardness of the tempered martensite: 800 to 10500.

公开(公告)号：US20200040435A1

公开(公告)日：2020-02-06

申请号：US16335446

申请日：2017-01-25

Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION

Inventor： Katsuya NAKANO ,  Kunio HAYASHI ,  Yuri TODA ,  Eisaku SAKURADA ,  Akihiro UENISHI

IPC: C22C38/40 ,  B32B15/01 ,  C22C38/32 ,  C22C38/28 ,  C22C38/24 ,  C22C38/26 ,  C22C38/20 ,  C22C38/22 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  C23C2/40 ,  C23C2/02

Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 50% to 95%, granular bainite: 5% to 48%, martensite: 2% to 30%, and upper bainite, lower bainite, tempered martensite, retained austenite, and pearlite: 5% or less in total.

公开(公告)号：US20190226046A1

公开(公告)日：2019-07-25

申请号：US16330336

申请日：2016-09-13

Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION

Inventor： Yuri TODA ,  Kunio HAYASHI ,  Katsuya NAKANO ,  Hiroyuki KAWATA ,  Akihiro UENISHI

IPC: C21D9/46 ,  B32B15/01 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/20 ,  C23F17/00

Abstract: A steel sheet according to an aspect of the present invention has a chemical composition within a predetermined range; in which a metallographic structure at a thickness ¼ portion includes, by unit area %, ferrite: 10% or more and less than 50%, granular bainite: 5% or more and less than 50%, and martensite: 20% or more and less than 60%; in the metallographic structure at the thickness ¼ portion, a total of upper bainite, lower bainite, residual austenite, and pearlite is 0% or more and less than 15% by unit area %; at the thickness ¼ portion, a product of an area ratio Vm of the martensite and an average hardness Hv of the martensite is 12,000 to 34,000; and a tensile strength is 980 MPa or higher.