EP 2684975 A1 20140115 - Cold rolled steel flat product and method for its production
Title (en)
Cold rolled steel flat product and method for its production
Title (de)
Kaltgewalztes Stahlflachprodukt und Verfahren zu seiner Herstellung
Title (fr)
Produit plat en acier laminé à froid et son procédé de fabrication
Publication
Application
Priority
EP 12175756 A 20120710
Abstract (en)
Cold reduced flat steel product comprises perlite and bainite structure comprising 20-40 vol.% of martensite, 2-15 vol.% of retained austenite and residual ferrite. The flat steel product is made of a steel consisting of 0.12-0.19 wt.% of carbon, 1.5-2.5 wt.% of manganese, 0.60-1 wt.% of silicon, = 0.1 wt. of aluminum, 0.2-0.6 wt.% of chromium, 0.05-0.15 wt.% of titanium, and remaining iron and unavoidable impurities, and has an elongation at rupture (A80) of 15%, a tensile strength of at least 880 MPa, a yield strength of at least 550 MPa, and hole expansion ratio of more than 6%. An independent claim is included for producing the cold-rolled flat steel product comprising Casting a steel melt containing of carbon, manganese, silicon, aluminum, chromium, titanium and remaining iron and unavoidable impurities to form an intermediate in which there is a slab or thin slab, heating the intermediate at an austenitizing temperature of 1100-1300[deg] C, hot rolling the heated intermediate to form a hot strip at a temperature of 850-960[deg] C, cooling the hot strip at a coiling temperature of 500-650[deg] C, rolling the cooled strip using a roller, optionally pickling the hot-rolled strip, cold-rolling the hot-rolled strip into a cold-rolled flat steel product having cold rolling ratio of at least 30%, continuously annealing the cold-rolled steel flat product at a temperature of 750-900[deg] C for 80-300 seconds, and then cooling in two stages, aging the flat steel product at an aging temperature of 100-400[deg] C for 210-710 seconds, cooling the flat product to room temperature, temper-rolling the flat steel product with a roll of 0.2-2%, and optional coating the flat steel product with a metallic protective layer, where the step of cooling the cold-rolled steel flat product includes in the first stage, cooling the product with a cooling rate of 8-100[deg] C/sec to a temperature of 450-550[deg] C and in the second stage, cooling from the intermediate temperature at a cooling rate of 2-100[deg] K/second to a temperature of 350-450[deg] C.
Abstract (de)
Die Erfindung betrifft ein kaltgewalztes Stahlflachprodukt, das trotz hoher Festigkeitswerte eine durch eine hohe Bruchdehnung und ein gutes Lochaufweitungsverhältnis » M gekennzeichnete Verformbarkeit besitzt. Dazu ist das Stahlflachprodukt aus einem Stahl hergestellt ist, der aus (in Gew.-%) C: 0,12 - 0,19 %, Mn: 1,5 - 2,5 %, Si: >0,60 - 1,0 %, Al : ‰¤ 0,1 %, Cr: 0,2 - 0,6 %, Ti: 0,05 - 0,15 % und als Rest aus Eisen sowie herstellungsbedingt unvermeidbaren Verunreinigungen besteht, und weist ein perlit- und bainitfreies Gefüge mit 4 - 20 Vol. -% Martensit, 2 - 15 Vol.-% Restaustenit, Rest Ferrit, eine Bruchdehnung A80 von mindestens 15 %, eine Zugfestigkeit Rm von mindestens 880 MPa, eine Streckgrenze ReL von mindestens 550 MPa und ein Lochaufweitungsverhältnis » M von mehr als 6 % auf. Ebenso betrifft die Erfindung ein Verfahren, das auf einfache Weise die Herstellung eines erfindungsgemäßen Stahlflachprodukts ermöglicht.
IPC 8 full level
C21D 8/02 (2006.01); C21D 9/46 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/28 (2006.01); C22C 38/38 (2006.01)
CPC (source: EP KR US)
C21D 8/0226 (2013.01 - EP KR US); C21D 8/0236 (2013.01 - EP KR US); C21D 8/0263 (2013.01 - EP US); C21D 8/0273 (2013.01 - EP KR US); C21D 8/0284 (2013.01 - EP US); C21D 9/46 (2013.01 - EP US); C22C 38/001 (2013.01 - EP US); C22C 38/002 (2013.01 - EP US); C22C 38/02 (2013.01 - EP US); C22C 38/04 (2013.01 - KR US); C22C 38/06 (2013.01 - EP US); C22C 38/28 (2013.01 - EP US); C22C 38/38 (2013.01 - EP KR US); C22C 38/50 (2013.01 - KR); C21D 2211/001 (2013.01 - EP US); C21D 2211/002 (2013.01 - EP US); C21D 2211/005 (2013.01 - EP US); C21D 2211/008 (2013.01 - EP US); C21D 2211/009 (2013.01 - EP US)
Citation (applicant)
- EP 2028282 A1 20090225 - THYSSENKRUPP STEEL AG [DE]
- WOESTMANN, S.; KÖHLER, T.; SCHOTT, M.: "Forming High-Strength Steels", SAE TECHNICAL PAPER 2009-01-0802, 2009
Citation (search report)
- [I] EP 2258886 A1 20101208 - JFE STEEL CORP [JP]
- [I] EP 2182080 A1 20100505 - KOBE STEEL LTD [JP]
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
Designated extension state (EPC)
BA ME
DOCDB simple family (publication)
EP 2684975 A1 20140115; EP 2684975 B1 20161109; BR 112014021543 B1 20200317; CN 104471096 A 20150325; CN 104471096 B 20170815; ES 2614465 T3 20170531; JP 2015528058 A 20150924; JP 6236078 B2 20171122; KR 102128563 B1 20200708; KR 20150031407 A 20150324; PL 2684975 T3 20170831; US 10344344 B2 20190709; US 2015000797 A1 20150101; WO 2014009404 A1 20140116
DOCDB simple family (application)
EP 12175756 A 20120710; BR 112014021543 A 20130710; CN 201380036484 A 20130710; EP 2013064551 W 20130710; ES 12175756 T 20120710; JP 2015520969 A 20130710; KR 20147021943 A 20130710; PL 12175756 T 20120710; US 201314377398 A 20130710