公开(公告)号：US11920208B2

公开(公告)日：2024-03-05

申请号：US16954510

申请日：2018-12-18

Applicant: ArcelorMittal

Inventor： Coralie Jung ,  Astrid Perlade ,  Kangying Zhu ,  Frédéric Kegel

IPC: C21D9/46 ,  B23K11/16 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/02 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23C2/40 ,  B23K101/00

CPC classification number: C21D9/46 ,  B23K11/16 ,  B32B15/012 ,  B32B15/013 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/06 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/06 ,  C23C2/12 ,  C23C2/29 ,  C23C2/40 ,  B23K2101/006 ,  C21D2211/001 ,  C21D2211/003 ,  C21D2211/005 ,  C21D2211/008

Abstract: A cold-rolled and heat-treated steel sheet, has a composition comprising, by weight percent: n0.10%≤C≤0.25%, 3.5%≤Mn—≤6.0%, 0.5%≤Si≤2.0%, 0.3%≤Al≤1.2%, with Si+Al≥0.8%, 0.10%≤Mo≤0.50%, S≤0.010%, P≤0.020%, N≤0.008%. The cold-rolled steel sheet has a microstructure consisting of, in surface fraction: between 10% and 45% of ferrite, having an average grain size of at most 1.3 μm, the product of the surface fraction of ferrite by the average grain size of the ferrite being of at most 35 μm %, between 8% and 30% of retained austenite, the retained austenite having an Mn content higher than 1.1*Mn %, Mn % designating the Mn content of the steel, at most 8% of fresh martensite, at most 2.5% of cementite and partitioned martensite.

公开(公告)号：US11530459B2

公开(公告)日：2022-12-20

申请号：US16765207

申请日：2018-11-21

Applicant: ArcelorMittal

Inventor： Kangying Zhu ,  Astrid Perlade ,  Coralie Jung ,  Frederic Kegel

IPC: C21D9/46 ,  C21D8/02 ,  B23K20/12 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C23C2/06 ,  C23C2/12

Abstract: A cold-rolled and heat-treated steel sheet having a microstructure of, in surface fraction: between 10% and 30% of retained austenite, said retained austenite being present as films having an aspect ratio of at least 3 and as Martensite Austenite islands, less than 8% of such Martensite Austenite islands having a size above 0.5 μm, at most 10% of fresh martensite and recovered martensite containing precipitates of at least one element chosen among niobium, titanium and vanadium. A manufacturing method thereof is also provided.

公开(公告)号：US10895003B2

公开(公告)日：2021-01-19

申请号：US16276242

申请日：2019-02-14

Applicant: ArcelorMittal

Inventor： Kangying Zhu ,  Olivier Bouaziz

IPC: C22C38/38 ,  C22C38/04 ,  C22C38/18 ,  C22C38/22 ,  C22C38/02 ,  C22C38/06 ,  C22C38/34 ,  C21D1/19 ,  C21D7/13 ,  C21D8/02 ,  C21D9/46 ,  C21D1/673

Abstract: The present invention provides a method for the fabrication of a steel sheet with a completely martensitic structure which has an average lath size of less than 1 micrometer and an average elongation factor of the laths is between 2 and 5. The elongation factor of a lath is defined as a maximum dimension lmax divided by and a minimum dimension lmin. The steel sheet has a yield stress greater than 1300 MPa and a mechanical strength greater than (3220(C)+958) megapascals. A composition of a semi-finished steel product includes, expressed in percent by weight, is, 0.15%≤C≤0.40%, 1.5%≤Mn≤3%, 0.005%≤Si≤2%, 0.005%≤Al≤0.1%, 1.8%≤Cr≤4%, 0%≤Mo≤2%, whereby: 2.7% 0.5 (Mn)+(Cr)+3(Mo)≤5.7%, S≤0.05%, P≤0.1%, optionally: 0%≤Nb≤0.050%, 0.01%≤Ti≤0.1%, 0.0005%≤B≤0.005%, 0.0005%≤Ca≤0.005%. The semi-finished product is reheated to a temperature T1 in the range between 1050° C. and 1250° C., then subjected to a roughing rolling at a temperature T2 in the range between 1000 and 880° C., with a cumulative rate of reduction εa greater than 30%, to obtain a sheet with a completely recrystallized austenitic structure with an average grain size less than 40 micrometers and preferably less than 5 micrometers. The sheet is then partially cooled to prevent a transformation of the austenite at a rate VR1 greater than 2° C./s to a temperature T3 between 600° C. and 400° C. in the metastable austenitic range, and subjected to a finishing hot rolling at the temperature T3 of the partially cooled sheet, with a cumulative rate of reduction εb greater than 30% to obtain a sheet that is then cooled at a rate VR2 which is greater than the critical martensitic quenching rate.

公开(公告)号：US20170321294A1

公开(公告)日：2017-11-09

申请号：US15526902

申请日：2015-11-17

Applicant: ArcelorMittal

Inventor： Artem Arlazarov ,  Kangying Zhu

IPC: C21D8/02 ,  C23C2/06 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C21D9/46 ,  C23C2/12 ,  C21D1/18

CPC classification number: C21D8/0205 ,  C21D1/18 ,  C21D1/185 ,  C21D7/13 ,  C21D8/0226 ,  C21D8/0263 ,  C21D9/46 ,  C21D2211/001 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/34 ,  C22C38/38 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28

Abstract: A method for manufacturing a steel product, is provided. A heated steel starting product at a temperature between 380° C. and 700° C., having a metastable fully austenitic structure, with a composition including, in percent by weight: 0.15%≦C≦0.40%, 1.5%≦Mn≦4.0%, 0.5%≦Si≦2.5%, 0.005%≦Al≦1.5%, with 0.8%≦Si+Al≦2.5%, S≦0.05%, P≦0.1%, at least one element chosen among Cr and Mo, such that: 0%≦Cr≦4.0%, 0%≦Mo≦0.5%, and 2.7%≦Mn+Cr+3 Mo≦5.7% is provided. Then the starting product is hot formed at a temperature between 700° C. and 380° C., with a cumulated strain εb between 0.1 and 0.7, in at least one location of the heated steel starting product, to obtain a fully austenitic hot-formed steel product; quenched by cooling the product down, at a cooling rate VR2 superior to the critical martensitic cooling rate, to a quenching temperature QT lower than Ms in order to obtain a structure containing between 40% and 90% of martensite, the rest of the structure being austenite; then maintained at, or reheated up to a holding temperature PT between QT and 470° C. and holding the product at the temperature PT for a duration Pt between 5 s and 600 s

公开(公告)号：US11591665B2

公开(公告)日：2023-02-28

申请号：US16956390

申请日：2018-12-18

Applicant: ArcelorMittal

Inventor： Coralie Jung ,  Astrid Perlade ,  Kangying Zhu ,  Frédéric Kegel

IPC: C01D9/00 ,  C21D8/00 ,  C22C38/00 ,  C23C2/12 ,  C21D9/46 ,  C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/32 ,  C23C2/06

Abstract: A cold-rolled and heat treated steel sheet, has a composition comprising 0.1%≤C≤0.4%, 3.5%≤Mn≤8.0%, 0.1%≤Si≤1.5%, Al≤3%, Mo≤0.5%, Cr≤1%, Nb≤0.1%, Ti≤0.1%, V≤0.2%, B≤0.004%, 0.002%≤N≤0.013%, S≤0.003%, P≤0.015%. The structure consists of, in surface fraction: between 8 and 50% of retained austenite, at most 80% of intercritical ferrite, the ferrite grains, if any, having an average size of at most 1.5 μm, and at most 1% of cementite, the cementite particles having an average size lower than 50 nm, martensite and/or bainite.

公开(公告)号：US11590599B2

公开(公告)日：2023-02-28

申请号：US16492437

申请日：2018-02-27

Applicant: ArcelorMittal ,  Universite de Nantes

Inventor： Céline Musik ,  Kangying Zhu ,  Didier Hun ,  Jean-Michel Mataigne ,  Astrid Perlade ,  Renaud Frappier

IPC: B23K11/11 ,  B23K11/16 ,  B32B15/01 ,  B23K101/18 ,  B23K103/04 ,  B23K101/34 ,  B23K101/00

Abstract: A method for resistance spot welding comprising the following successive steps: —providing at least two steel sheets with thickness (th) comprised between 0.5 and 3 mm, at least one of the sheets being a zinc or zinc-alloy coated steel sheet (A) with a tensile strength (TS) higher than 800 MPa and a total elongation (TEL) such as (TS)×(TEL)>14000 MPa %, wherein the composition of the steel substrate of (A) contains, in weight: 0.05%≤C≤0.4%, 0.3%≤Mn≤8%, 0.010%≤Al≤3%, 0.010%≤Si≤2.09%, with 0.5%≤(Si+Al)≤3.5%, 0.001%≤Cr≤1.0%, 0.001%≤Mo≤0.5% and optionally: 0.005%≤Nb≤0.1%, 0.005%≤V≤0.2%, 0.005%≤Ti≤0.1%, 0.0003%≤B≤0.005%, 0.001%≤Ni≤1.0%, the remainder being Fe and unavoidable impurities, —performing resistance spot welding of the at least two steel sheets for producing a weld with an indentation depth (IDepth) on the surface of said steel sheet (A) such as: 100 μm≤(IDepth)≤18.68 (Znsol)−55.1, wherein (IDepth) is in micrometers and wherein Znsol is the solubility of Zn in the steel of sheet (A) at 750° C., in weight %.

公开(公告)号：US11434541B2

公开(公告)日：2022-09-06

申请号：US16332619

申请日：2017-09-15

Applicant: ArcelorMittal

Inventor： Coralie Magar ,  Kangying Zhu ,  Astrid Perlade

IPC: C21D8/02 ,  B23K11/11 ,  C21D1/18 ,  C21D6/00 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/12 ,  C23C2/40

Abstract: A cold-rolled and heat-treated steel sheet, having a composition including, by weight percent: 0.10%≤C≤0.40%, 3.5%≤Mn≤8.0%, 0.5%≤Si≤2.5%, 0.003%≤Al≤3.0%, with Si+Al≥0.8%, 0.001%≤Mo≤0.5%, S≤0.010%, P≤0.020%, N≤0.008%, and optionally one or more elements selected from a group comprising Cr, Ti, Nb, V and B, such that: 0.01%≤Cr≤2.0%, 0.010%≤Ti≤0.080%, 0.010%≤Nb≤0.080%, 0.010%≤V≤0.30%, 0.0005%≤B≤0.003%, the remainder of the composition being iron and unavoidable impurities resulting from the smelting. The microstructure includes, in surface fraction, between 10% and 50% of retained austenite, at most 8% of fresh martensite, and tempered martensite. The retained austenite includes Mn-enriched austenite, having a Mn content higher than 1.3*Mn %, Mn % designating the Mn content of the steel sheet, a surface fraction of the Mn-enriched austenite with respect to the whole microstructure is between 2% and 12%, and Mn-poor austenite, having an Mn content between 0.5*Mn % and 1.3*Mn %.

公开(公告)号：US11371109B2

公开(公告)日：2022-06-28

申请号：US15526902

申请日：2015-11-17

Applicant: ArcelorMittal

Inventor： Artem Arlazarov ,  Kangying Zhu

IPC: C21D8/02 ,  C21D9/46 ,  C21D1/18 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/00 ,  C23C2/06 ,  C23C2/12 ,  C22C38/32 ,  C21D7/13 ,  C22C38/28 ,  C22C38/38 ,  C23C2/28 ,  C22C38/26 ,  C22C38/12 ,  C22C38/34 ,  C22C38/14

Abstract: A method for manufacturing a steel product includes providing a heated steel starting product at a temperature between 380° C. and 700° C., having a metastable fully austenitic structure, with a specified composition. Then the starting product is hot formed at a temperature between 700° C. and 380° C., with a cumulated strain εb between 0.1 and 0.7, in at least one location of the heated steel starting product, to obtain a fully austenitic hot-formed steel product; quenched by cooling the product down, at a cooling rate VR2 superior to the critical martensitic cooling rate, to a quenching temperature QT lower than Ms in order to obtain a structure containing between 40% and 90% of martensite, the rest of the structure being austenite; then maintained at, or reheated up to a holding temperature PT between QT and 470° C. and holding the product at the temperature PT for a duration Pt between 5 s and 600 s.

公开(公告)号：US20200009679A1

公开(公告)日：2020-01-09

申请号：US16492437

申请日：2018-02-27

Applicant: ArcelorMittal ,  Universite de Nantes

Inventor： Céline Musik ,  Kangying Zhu ,  Didier Hun ,  Jean-Michel Mataigne ,  Astrid Perlade ,  Renaud Frappier

IPC: B23K11/11 ,  B23K11/16 ,  B32B15/01

Abstract: A method for resistance spot welding comprising the following successive steps: —providing at least two steel sheets with thickness (th) comprised between 0.5 and 3 mm, at least one of the sheets being a zinc or zinc-alloy coated steel sheet (A) with a tensile strength (TS) higher than 800 MPa and a total elongation (TEL) such as (TS)×(TEL)>14000 MPa %, wherein the composition of the steel substrate of (A) contains, in weight: 0.05%≤C≤0.4%, 0.3%≤Mn≤8%, 0.010%≤Al≤3%, 0.010%≤Si≤2.09%, with 0.5%≤(Si+Al)≤3.5%, 0.001%≤Cr≤1.0%, 0.001%≤Mo≤0.5% and optionally: 0.005%≤Nb≤0.1%, 0.005%≤V≤0.2%, 0.005%≤Ti≤0.1%, 0.0003%≤B≤0.005%, 0.001%≤Ni≤1.0%, the remainder being Fe and unavoidable impurities, —performing resistance spot welding of the at least two steel sheets for producing a weld with an indentation depth (IDepth) on the surface of said steel sheet (A) such as: 100 μm≤(IDepth)≤18.68 (Znsol)−55.1, wherein (IDepth) is in micrometers and wherein Znsol is the solubility of Zn in the steel of sheet (A) at 750° C., in weight %.

公开(公告)号：US20190226060A1

公开(公告)日：2019-07-25

申请号：US16276242

申请日：2019-02-14

Applicant: ArcelorMittal

Inventor： Kangying Zhu ,  Olivier Bouaziz

IPC: C22C38/38 ,  C21D1/673 ,  C22C38/34 ,  C22C38/06 ,  C22C38/02 ,  C21D8/02 ,  C22C38/22 ,  C21D1/19 ,  C22C38/04 ,  C22C38/18 ,  C21D9/46 ,  C21D7/13

Abstract: The present invention provides a method for the fabrication of a steel sheet with a completely martensitic structure which has an average lath size of less than 1 micrometer and an average elongation factor of the laths is between 2 and 5. The elongation factor of a lath is defined as a maximum dimension lmax divided by and a minimum dimension lmin. The steel sheet has a yield stress greater than 1300 MPa and a mechanical strength greater than (3220(C)+958) megapascals. A composition of a semi-finished steel product includes, expressed in percent by weight, is, 0.15%≤C≤0.40%, 1.5%≤Mn≤3%, 0.005%≤Si≤2%, 0.005%≤Al≤0.1%, 1.8%≤Cr≤4%, 0%≤Mo≤2%, whereby: 2.7% 0.5 (Mn)+(Cr)+3(Mo)≤5.7%, S≤0.05%, P≤0.1%, optionally: 0%≤Nb≤0.050%, 0.01%≤Ti≤0.1%, 0.0005%≤B≤0.005%, 0.0005%≤Ca≤0.005%. The semi-finished product is reheated to a temperature T1 in the range between 1050° C. and 1250° C., then subjected to a roughing rolling at a temperature T2 in the range between 1000 and 880° C., with a cumulative rate of reduction εa greater than 30%, to obtain a sheet with a completely recrystallized austenitic structure with an average grain size less than 40 micrometers and preferably less than 5 micrometers. The sheet is then partially cooled to prevent a transformation of the austenite at a rate VR1 greater than 2° C./s to a temperature T3 between 600° C. and 400° C. in the metastable austenitic range, and subjected to a finishing hot rolling at the temperature T3 of the partially cooled sheet, with a cumulative rate of reduction εb greater than 30% to obtain a sheet that is then cooled at a rate VR2 which is greater than the critical martensitic quenching rate.