EP 2707513 B1 20161109 - METHOD FOR THE PRODUCTION OF VERY-HIGH-STRENGTH MARTENSITIC STEEL AND SHEET OR PART THUS OBTAINED
Title (en)
METHOD FOR THE PRODUCTION OF VERY-HIGH-STRENGTH MARTENSITIC STEEL AND SHEET OR PART THUS OBTAINED
Title (de)
VERFAHREN ZUR HERSTELLUNG VON MARTENSITISCHEM STAHL VON SEHR HOHER STÄRKE UND FOLIE ODER TEIL AUS DIESEM VERFAHREN
Title (fr)
PROCEDE DE FABRICATION D'ACIER MARTENSITIQUE A TRES HAUTE RESISTANCE ET TÔLE OU PIECE AINSI OBTENUE
Publication
Application
Priority
- FR 2011000294 W 20110512
- FR 2012000153 W 20120420
Abstract (en)
[origin: WO2012153008A1] The invention relates to a method for the production of a martensitic steel sheet having a yield point greater than 1300 MPa and mechanical strength greater than (3220(C)+958) megapascals, (C) denoting the carbon weight content of the steel. The method comprises the following steps consisting in: supplying a semi-finished steel product having a composition containing, expressed as weight, 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%, wherein 2.7% = 0.5 (Mn)+(Cr)+3(Mo) = 5.7%, S = 0.05%, P = 0.1 % and, optionally, 0% = Nb = 0.050%, 0.01 % = Ti = 0.1 %, 0.0005% = B = 0.005%, 0.0005% = Ca = 0.005%, the remainder of the composition being formed by iron and the inevitable impurities resulting from production; heating the semi-finished product to a temperature T1 between 1050°C and 1250°C and, subsequently, subjecting the heated semi-finished product to rough rolling at a temperature T2 between 1000 and 880°C, with a cumulative reduction rate ea greater than 30%, such as to obtain a sheet having an austenitic structure that is totally recrystallised, with an average grain size of less than 40 micrometres and preferably less than 5 micrometres; and partially cooling the sheet, such as to prevent the 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, subsequently, subjecting the not completely cooled sheet to final hot rolling at temperature T3, with a cumulative reduction rate eb greater than 30%, such as to obtain a sheet that is cooled at a rate VR2 above the critical cooling rate.
IPC 8 full level
C21D 1/19 (2006.01); C21D 1/673 (2006.01); C21D 7/13 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/04 (2006.01); C22C 38/18 (2006.01); C22C 38/22 (2006.01)
CPC (source: EP KR US)
C21D 1/19 (2013.01 - EP KR US); C21D 1/673 (2013.01 - EP US); C21D 7/13 (2013.01 - EP KR US); C21D 8/02 (2013.01 - KR); C21D 8/0226 (2013.01 - EP US); C21D 8/0231 (2013.01 - EP US); C21D 8/0263 (2013.01 - EP US); C21D 9/46 (2013.01 - EP KR US); C22C 38/02 (2013.01 - EP US); C22C 38/04 (2013.01 - EP KR US); C22C 38/06 (2013.01 - EP US); C22C 38/18 (2013.01 - EP KR US); C22C 38/22 (2013.01 - EP KR US); C22C 38/34 (2013.01 - EP US); C22C 38/38 (2013.01 - EP US); C21D 2211/008 (2013.01 - EP US)
Designated contracting state (EPC)
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
DOCDB simple family (publication)
WO 2012153008 A1 20121115; BR 112013028931 A2 20170207; BR 112013028931 B1 20190306; BR 122018069395 B1 20190424; CA 2835533 A1 20121115; CA 2835533 C 20181204; CN 103562417 A 20140205; CN 103562417 B 20150729; EP 2707513 A1 20140319; EP 2707513 B1 20161109; ES 2612514 T3 20170517; HU E031878 T2 20170828; JP 2014517149 A 20140717; JP 6114261 B2 20170412; KR 101590689 B1 20160201; KR 20140019838 A 20140217; KR 20150095949 A 20150821; MA 35058 B1 20140403; MX 2013013220 A 20140623; MX 359665 B 20181005; PL 2707513 T3 20170428; RU 2013155181 A 20150620; RU 2580578 C2 20160410; UA 113628 C2 20170227; US 10337090 B2 20190702; US 10895003 B2 20210119; US 2014076470 A1 20140320; US 2019226060 A1 20190725; WO 2012153012 A1 20121115; ZA 201309348 B 20140730
DOCDB simple family (application)
FR 2011000294 W 20110512; BR 112013028931 A 20120420; BR 122018069395 A 20120420; CA 2835533 A 20120420; CN 201280022858 A 20120420; EP 12724656 A 20120420; ES 12724656 T 20120420; FR 2012000153 W 20120420; HU E12724656 A 20120420; JP 2014509779 A 20120420; KR 20137032514 A 20120420; KR 20157021040 A 20120420; MA 36353 A 20131022; MX 2013013220 A 20120420; PL 12724656 T 20120420; RU 2013155181 A 20120420; UA A201314471 A 20120420; US 201214116991 A 20120420; US 201916276242 A 20190214; ZA 201309348 A 20131021