公开(公告)号：US20180080100A1

公开(公告)日：2018-03-22

申请号：US15561786

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  C22C38/28 ,  C22C38/26 ,  C22C38/16 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  B32B15/01

CPC classification number: C21D9/46 ,  B32B15/013 ,  B32B2311/20 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0247 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/42 ,  C22C38/44 ,  C22C38/60 ,  C23C2/06

Abstract: A high-strength steel sheet having a tensile strength of at least 780 MPa and excellent punchability comprises a ferrite phase, a martensite phase, and a bainite phase. The area ratio of the martensite phase is 20%-50%; the area ratio of crystal grains having an average crystal grain diameter of less than 1.0 μm in the martensite phase is 5%-30%; the area ratio of crystal grains having an average crystal grain diameter of 1.0-4.0 μm is 70%-95%; and the area ratio of crystal grains having an average crystal grain diameter of more than 4.0 μm is less than 5%.

公开(公告)号：US20190032187A1

公开(公告)日：2019-01-31

申请号：US16072668

申请日：2017-01-26

Applicant: JFE Steel Corporation

Inventor： HIROMI YOSHITOMI ,  Hiroyuki Masuoka ,  Seisuke Tsuda ,  Yasuhiro Nishimura ,  Masaki Koba

IPC: C23C2/06 ,  C22C38/02 ,  C22C38/06 ,  C22C38/00 ,  C22C38/60 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/38 ,  C22C38/22 ,  C22C38/32 ,  C22C38/26 ,  C22C38/28 ,  C22C38/08 ,  C23C2/40 ,  C23C2/28 ,  C23C2/02 ,  C21D8/02

Abstract: Provided are a high-yield-ratio high-strength galvanized steel sheet and a method for manufacturing thereof. The high-yield-ratio high-strength galvanized steel sheet has a steel sheet having a specified chemical composition and a metallographic structure including, in terms of area ratio, in terms of area ratio, 15% or less of ferrite, 20% or more and 50% or less of martensite, and bainite and tempered martensite in a total amount of 30% or more, and a galvanized layer formed on the steel sheet having a coating weight of 20 g/m2 to 120 g/m2 per side, in which a yield strength ratio is 65% or more, a tensile strength is 950 MPa or more, and Mn oxides are contained in the galvanized layer in an amount of 0.015 g/m2 to 0.050 g/m2.

公开(公告)号：US11001906B2

公开(公告)日：2021-05-11

申请号：US15561786

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C23C2/06 ,  C22C38/60 ,  C22C38/14 ,  C22C38/42 ,  C22C38/22 ,  C22C38/44 ,  C22C38/12

Abstract: A high-strength steel sheet having a tensile strength of at least 780 MPa and excellent punchability comprises a ferrite phase, a martensite phase, and a bainite phase. The area ratio of the martensite phase is 20%-50%; the area ratio of crystal grains having an average crystal grain diameter of less than 1.0 μm in the martensite phase is 5%-30%; the area ratio of crystal grains having an average crystal grain diameter of 1.0-4.0 μm is 70%-95%; and the area ratio of crystal grains having an average crystal grain diameter of more than 4.0 μm is less than 5%.

公开(公告)号：US11473180B2

公开(公告)日：2022-10-18

申请号：US16072668

申请日：2017-01-26

Applicant: JFE Steel Corporation

Inventor： Hiromi Yoshitomi ,  Hiroyuki Masuoka ,  Seisuke Tsuda ,  Yasuhiro Nishimura ,  Masaki Koba

IPC: C23C2/06 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40 ,  C21D9/46 ,  C22C38/14 ,  C22C38/60 ,  C22C38/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38

Abstract: Provided are a high-yield-ratio high-strength galvanized steel sheet and a method for manufacturing thereof. The high-yield-ratio high-strength galvanized steel sheet has a steel sheet having a specified chemical composition and a metallographic structure including, in terms of area ratio, in terms of area ratio, 15% or less of ferrite, 20% or more and 50% or less of martensite, and bainite and tempered martensite in a total amount of 30% or more, and a galvanized layer formed on the steel sheet having a coating weight of 20 g/m2 to 120 g/m2 per side, in which a yield strength ratio is 65% or more, a tensile strength is 950 MPa or more, and Mn oxides are contained in the galvanized layer in an amount of 0.015 g/m2 to 0.050 g/m2.

公开(公告)号：US10570476B2

公开(公告)日：2020-02-25

申请号：US15561224

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C23C2/06 ,  C23C2/28

Abstract: A high-strength steel sheet having excellent punchability and a tensile strength of at least 780 MPa has a steel structure containing, by area ratio, 70%-90% ferrite phase and 10%-30% martensite phase. The non-recrystallized ferrite content in the ferrite phase is 30%-50% and the ratio of crystal grains having an aspect ratio of 1.0-1.5 in the martensite phase is 40%-100%, by area ratio.

公开(公告)号：US20180057907A1

公开(公告)日：2018-03-01

申请号：US15561224

申请日：2015-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Kenji Kawamura ,  Noriaki Kohsaka ,  Yasuhiro Nishimura

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/28 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/28 ,  C23C2/06 ,  B32B15/01

Abstract: A high-strength steel sheet having excellent punchability and a tensile strength of at least 780 MPa has a steel structure containing, by area ratio, 70%-90% ferrite phase and 10%-30% martensite phase. The non-recrystallized ferrite content in the ferrite phase is 30%-50% and the ratio of crystal grains having an aspect ratio of 1.0-1.5 in the martensite phase is 40%-100%, by area ratio.