公开(公告)号：US11555226B2

公开(公告)日：2023-01-17

申请号：US15322712

申请日：2015-07-03

Applicant: ArcelorMittal

Inventor： Rashmi Ranjan Mohanty ,  Hyun Jo Jun ,  Dongwei Fan ,  Pavan K. C. Venkatasurya

IPC: C21D9/46 ,  C22C38/06 ,  C22C38/14 ,  C22C38/02 ,  C22C38/04 ,  C22C38/12 ,  C21D9/48 ,  C21D1/19 ,  C21D8/04 ,  C21D1/18 ,  C21D6/00

Abstract: A method for producing a high strength uncoated steel sheet having an improved strength and an improved formability, including the steps of: providing an uncoated steel sheet; annealing the sheet at an annealing temperature TA higher than 865° C. but less than 1000° C. for a time of more than 30 s; cooling the sheet down to a quenching temperature QT between 310° C. and 375° C., at a cooling speed of at least 30° C./s; heating the sheet up to a partitioning temperature PT between 370° C. and 470° C. and maintaining the sheet at the partitioning temperature for a partitioning time Pt between 50 s and 150 s; and cooling the sheet down to the room temperature.

公开(公告)号：US10995383B2

公开(公告)日：2021-05-04

申请号：US15322722

申请日：2015-07-03

Applicant: ArcelorMittal

Inventor： Dongwei Fan ,  Hyun Jo Jun ,  Rashmi Ranjan Mohanty

IPC: C21D9/46 ,  C21D6/00 ,  C23C2/06 ,  C21D8/04 ,  C21D8/02 ,  C21D1/19 ,  B32B15/01 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40

Abstract: A method for producing a high strength coated steel sheet having a yield strength YS of at least 800 MPa, a tensile strength TS of >1180 MPa, a total elongation >14% and a hole expansion ratio HER >30%. The steel contains in weight %: 0.13%≤C≤0.22%, 1.2%≤Si≤1.8%, 1.8%≤Mn≤2.2%, 0.10%≤Mo≤0.20%, Nb≤0.05%, Al≤0.5%, the remainder being Fe and unavoidable impurities. The sheet is annealed at a temperature TA higher than Ac3 but less than 1000° C. for more than 30 s, then quenched by cooling temperature QT between 325° C. and 375° C., at a cooling speed sufficient to obtain a structure consisting of austenite and at least 60% of martensite, the austenite content being such that the final structure can contain between 3% and 15% of residual austenite and between 85 and 97% of the sum of martensite and bainite, without ferrite, then heated to a partitioning temperature PT between 430° C. and 480° C. and maintained at this temperature for a partitioning time Pt between 10 s and 90 s, then hot dip coated cooled to the room temperature. Coated sheet obtained.

公开(公告)号：US20200347477A1

公开(公告)日：2020-11-05

申请号：US16931001

申请日：2020-07-16

Applicant: ARCELORMITTAL

Inventor： Rashmi Ranjan Mohanty ,  Hyun Jo Jun ,  Dongwei Fan

IPC: C21D9/46 ,  B32B15/01 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40 ,  C21D8/02 ,  C21D1/18 ,  C22C38/02 ,  C22C38/38 ,  C22C38/34 ,  C22C38/06 ,  C22C38/58

Abstract: A method is for producing a high strength coated steel sheet having a yield stress YS>800 MPa, a tensile strength TS>1180 MPa, and improved formability and ductility. The steel contains: 15%≤C≤0.25%, 1.2%≤Si≤1.8%, 2%≤Mn≤2.4%, 0.1%≤Cr≤0.25%, Al≤0.5%, the remainder being Fe and unavoidable impurities. The sheet is annealed at a temperature higher than Ac3 and lower than 1000° C. for a time of more than 30 s, then quenched by cooling it to a quenching temperature QT between 250° C. and 350° C., to obtain a structure consisting of at least 60% of martensite and a sufficient austenite content such that the final structure contains 3% to 15% of residual austenite and 85% to 97% of martensite and bainite without ferrite, then heated to a partitioning temperature PT between 430° C. and 480° C. and maintained at this temperature for a partitioning time Pt between 10 s and 90 s, then hot dip coated and cooled to the room temperature.

公开(公告)号：US20170130290A1

公开(公告)日：2017-05-11

申请号：US15322722

申请日：2015-07-03

Applicant: ArcelorMittal

Inventor： Dogwei Fan ,  Hyun Jo Jun ,  Rashmi Ranjan Mohanty

IPC: C21D9/46 ,  C23C2/40 ,  C22C38/14 ,  C22C38/12 ,  B32B15/01 ,  C22C38/04 ,  C22C38/02 ,  C21D6/00 ,  C23C2/02 ,  C23C2/28 ,  C23C2/06 ,  C22C38/06

Abstract: A method for producing a high strength coated steel sheet having a yield strength YS of at least 800 MPa, a tensile strength TS of >1180 MPa, a total elongation >14% and a hole expansion ratio HER>30%. The steel contains in weight %: 0.13%≦C≦0.22%, 1.2%≦Si≦1.8%, 1.8%≦Mn≦2.2%, 0.10%≦Mo≦0.20%, Nb≦0.05%, Al≦0.5%, the remainder being Fe and unavoidable impurities. The sheet is annealed at a temperature TA higher than Ac3 but less than 1000° C. for more than 30 s, then quenched by cooling temperature QT between 325° C. and 375° C., at a cooling speed sufficient to obtain a structure consisting of austenite and at least 60% of martensite, the austenite content being such that the fmal structure can contain between 3% and 15% of residual austenite and between 85 and 97% of the sum of martensite and bainite, without ferrite, then heated to a partitioning temperature PT between 430° C. and 480° C. and maintained at this temperature for a partitioning time Pt between 10 s and 90 s, then hot dip coated cooled to the room temperature. Coated sheet obtained.