公开(公告)号：US10711333B2

公开(公告)日：2020-07-14

申请号：US15516698

申请日：2015-10-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Takeshi Yokota ,  Takako Yamashita ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/14 ,  C23C2/12 ,  C22C38/60 ,  C23C2/02 ,  C22C38/00 ,  C23C2/06 ,  C23C2/28 ,  B32B15/01 ,  B32B15/18 ,  B32B15/20 ,  C21D1/26 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C23C2/40 ,  C23F17/00 ,  C25D3/22

Abstract: Disclosed is a steel sheet having a predetermined chemical composition and a steel microstructure that contains, in area ratio, 15% or more and 55% or less of polygonal ferrite and 15% or more and 30% or less of martensite, and that contains, in volume fraction, 12% or more of retained austenite, in which the polygonal ferrite, the martensite, and the retained austenite have a mean grain size of 4 μm or less, 2 μm or less, and 2 μm or less, respectively, and each have a mean grain aspect ratio of 2.0 or less, and in which a value obtained by dividing an Mn content in the retained austenite in mass % by an Mn content in the polygonal ferrite in mass % equals 2.0 or more.

公开(公告)号：US10662495B2

公开(公告)日：2020-05-26

申请号：US15326116

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Kazunori Tahara ,  Takeshi Yokota ,  Kaneharu Okuda ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/04 ,  C22C38/60 ,  B32B15/01 ,  C21D1/60 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23G1/00

Abstract: Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 μm or less, and the tempered martensite has a mean free path of 1.2 μm or less.

公开(公告)号：US10392677B2

公开(公告)日：2019-08-27

申请号：US15521515

申请日：2015-10-05

Applicant: JFE STEEL CORPORATION

Inventor： Koichi Nakagawa ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C21D1/18 ,  C22C38/00 ,  C22C38/06 ,  C22C38/60 ,  C21D6/00 ,  C21D8/02 ,  C21D8/04 ,  C23C2/40 ,  C22C38/02 ,  C22C38/04 ,  C22C38/08 ,  C22C38/38 ,  B21D22/02 ,  B32B15/01 ,  C21D1/673 ,  C22C18/00 ,  C22C38/12 ,  C22C38/14 ,  C21D9/48

Abstract: A high-strength hot-pressed part having a specified chemical composition, a microstructure including, in terms of volume fraction, 80% or more of a martensite phase, in a range of 3.0% to 20.0% of a retained austenite phase, a tensile strength TS of 1500 MPa or more, and a uniform elongation uEl of 6.0% or more. A method for manufacturing the high-strength hot-pressed part, the method comprising performing a heating process and a hot press forming process on a raw material steel sheet in order to obtain a hot-pressed part having a specified shape.

公开(公告)号：US10472697B2

公开(公告)日：2019-11-12

申请号：US15547659

申请日：2016-01-27

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/60 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/04 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 μm or less. An inverse intensity ratio of γ-fiber to α-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of γ-fiber to α-fiber in the martensite and the tempered martensite is 1.00 or more.

公开(公告)号：US10954578B2

公开(公告)日：2021-03-23

申请号：US15520236

申请日：2015-10-29

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Takeshi Yokota ,  Takako Yamashita ,  Kazuhiro Seto

IPC: C21D9/46 ,  C23C2/12 ,  C23C2/28 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C22C38/14 ,  C22C38/00 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/02 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C23C2/40 ,  C23G1/00 ,  C25D3/22

Abstract: Disclosed is a steel sheet having a predetermined chemical composition and a steel microstructure that contains, in area ratio, 35% or more and 80% or less of polygonal ferrite and 5% or more and 25% or less of martensite, and that contains, in volume fraction, 8% or more of retained austenite, in which the polygonal ferrite, the martensite, and the retained austenite have a mean grain size of 6 μm or less, 3 μm or less, and 3 μm or less, respectively, and each have a mean grain aspect ratio of 2.0 or less, and in which a value obtained by dividing an Mn content in the retained austenite in mass % by an Mn content in the polygonal ferrite in mass % equals 2.0 or more.

公开(公告)号：US10570475B2

公开(公告)日：2020-02-25

申请号：US15327126

申请日：2015-08-05

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu Kawasaki ,  Hiroshi Matsuda ,  Yoshie Obata ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/32 ,  C22C38/14 ,  C22C38/60 ,  C21D8/02 ,  C23C2/28 ,  C23C2/40 ,  C23C2/06 ,  C22C38/12 ,  C22C38/28 ,  C22C38/38 ,  C22C18/04

Abstract: Disclosed is a high-strength steel sheet having a predetermined chemical composition, satisfying the condition that Mn content divided by B content equals 2100 or less, and a steel microstructure that contains, by area, 25-80% of ferrite and bainitic ferrite in total, 3-20% of martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, and an aggregate of retained austenite formed by seven or more identically-oriented retained austenite grains accounts for 60% or more by area of the entire retained austenite.

公开(公告)号：US10563279B2

公开(公告)日：2020-02-18

申请号：US14909253

申请日：2014-07-16

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C22C38/12 ,  C21D9/46 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C22C38/14 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/08 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C21D8/02 ,  C21D6/00 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C23C2/40

Abstract: A high strength steel sheet having a high Young's modulus, the steel sheet having a chemical composition including, by mass %, C: 0.060% or more and 0.150% or less, Si: 0.50% or more and 2.20% or less, Mn: 1.00% or more and 3.00% or less, and one or both of Ti: 0.001% or more and 0.200% or less and Nb: 0.001% or more and 0.200% or less, in which the contents of C, N, S, Ti, and Nb satisfy the equation 500≤C*≤1300. The steel sheet has a microstructure including ferrite in an amount of 20% or more and martensite in an amount of 5% or more, in terms of area ratio, such that the average grain size of the ferrite is 20.0 μm or less and the inverse intensity ratio of γ-fiber for α-fiber is 1.00 or more in the ferrite and the martensite.

公开(公告)号：US10385431B2

公开(公告)日：2019-08-20

申请号：US14909562

申请日：2014-07-16

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/12 ,  C21D8/02 ,  C22C38/60 ,  B21B1/22 ,  B21B3/00 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C22C38/00 ,  C22C38/58 ,  B32B15/01 ,  C21D6/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/38

Abstract: A high strength steel sheet having a high Young's modulus, the steel sheet having a chemical composition including, by mass %, C: 0.060% or more and 0.150% or less, Si: 0.50% or more and 2.20% or less, Mn: 1.00% or more and 3.00% or less, Nb: 0.001% or more and 0.200% or less, and V: 0.001% or more and 0.200% or less, in which the contents of C, Nb, and V satisfy the equation 500≤C*≤1300. The steel sheet has a microstructure including ferrite in an amount of 20% or more and martensite in an amount of 5% or more, in terms of area ratio, such that the average grain size of the ferrite is 20.0 μm or less and the inverse intensity ratio of γ-fiber for α-fiber is 1.00 or more in each of the ferrite and the martensite.

公开(公告)号：US08876987B2

公开(公告)日：2014-11-04

申请号：US14349234

申请日：2012-10-02

Applicant: JFE Steel Corporation

Inventor： Hiroshi Matsuda ,  Yoshimasa Funakawa ,  Kaneharu Okuda ,  Kazuhiro Seto

IPC: C22C38/04 ,  C22C38/06 ,  C22C38/02 ,  C21D8/02 ,  C22C38/00 ,  C22C38/12 ,  C22C38/14 ,  C23C2/02 ,  C22C38/28 ,  C22C38/38 ,  C22C38/32 ,  C22C38/16 ,  C22C38/08

CPC classification number: C21D8/0263 ,  C21D6/008 ,  C21D8/02 ,  C21D8/0226 ,  C21D8/0236 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  Y10S148/909 ,  Y10T428/12799

Abstract: A high strength pressed member has excellent ductility and stretch flangeability and tensile strength of 780-1400 MPa, with a predetermined steel composition and steel microstructure relative to the entire microstructure of steel sheet, where area ratio of martensite 5-70%, area ratio of retained austenite 5-40%, area ratio of bainitic ferrite in upper bainite 5% or more, and total thereof is 40% or more, 25% or more of martensite is tempered martensite, polygonal ferrite area ratio is above 10% and below 50% to the entire microstructure of steel sheet, and average grain size is 8 μm or less, average diameter of a group of polygonal ferrite grains is 15 μm or less, the group of polygonal ferrite grains represented by a group of ferrite grains of adjacent polygonal ferrite grains, and average carbon content in retained austenite is 0.70 mass % or more and tensile strength is 780 MPa or more.

Abstract translation: 高强度压制构件具有优异的延展性和拉伸凸缘性和拉伸强度为780-1400MPa，具有预定的钢组成和钢组织相对于钢板的整个微观结构，其中马氏体的面积比为5-70％，面积比为 残留奥氏体5-40％，贝氏体铁素体在上贝氏体中的面积率为5％以上，总计为40％以上，25％以上的马氏体回火马氏体，多边形铁素体面积率在10％以下且低于50 ％的平均粒径为8μm以下，多边形铁素体组的平均直径为15μm以下，由相邻的多边形的铁素体组的一组表示的多边形铁素体晶粒组 铁素体晶粒和残留奥氏体中的平均碳含量为0.70质量％以上，拉伸强度为780MPa以上。

公开(公告)号：US20140242416A1

公开(公告)日：2014-08-28

申请号：US14349234

申请日：2012-10-02

Applicant: JFE Steel Corporation

Inventor： Hiroshi Matsuda ,  Yoshimasa Funakawa ,  Kaneharu Okuda ,  Kazuhiro Seto

IPC: C23C2/02 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/16 ,  C22C38/00 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D8/02 ,  C22C38/14

CPC classification number: C21D8/0263 ,  C21D6/008 ,  C21D8/02 ,  C21D8/0226 ,  C21D8/0236 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  Y10S148/909 ,  Y10T428/12799

Abstract: A high strength pressed member has excellent ductility and stretch flangeability and tensile strength of 780-1400 MPa, with a predetermined steel composition and steel microstructure relative to the entire microstructure of steel sheet, where area ratio of martensite 5-70%, area ratio of retained austenite 5-40%, area ratio of bainitic ferrite in upper bainite 5% or more, and total thereof is 40% or more, 25% or more of martensite is tempered martensite, polygonal ferrite area ratio is above 10% and below 50% to the entire microstructure of steel sheet, and average grain size is 8 μm or less, average diameter of a group of polygonal ferrite grains is 15 μm or less, the group of polygonal ferrite grains represented by a group of ferrite grains of adjacent polygonal ferrite grains, and average carbon content in retained austenite is 0.70 mass % or more and tensile strength is 780 MPa or more.

Abstract translation: 高强度压制构件具有优异的延展性和拉伸凸缘性和拉伸强度为780-1400MPa，具有预定的钢组成和钢组织相对于钢板的整个微观结构，其中马氏体的面积比为5-70％，面积比为 残留奥氏体5-40％，贝氏体铁素体在上贝氏体中的面积率为5％以上，总计为40％以上，25％以上的马氏体回火马氏体，多边形铁素体面积率在10％以下且低于50 ％的平均粒径为8μm以下，多边形铁素体组的平均直径为15μm以下，由相邻的多边形的铁素体组的一组表示的多边形铁素体晶粒组 铁素体晶粒和残留奥氏体中的平均碳含量为0.70质量％以上，拉伸强度为780MPa以上。