High tensile steel containing Mn, steel surface product made from such steel and method for producing same

Steel with an elongation at break A80 of minimum 4% and a tensile strength of 900-1500 MPa, comprises iron and unavoidable impurities comprising carbon (up to 0.5%), manganese (4-12%), silicon (up to 1%), aluminum (up to 3%), chromium (0.1-4%), copper (up to 2%), nickel (up to 2%), nitrogen (up to 0.05%), phosphorus (up to 0.05%), and sulfur (up to 0.01%), and optionally at most 0.5% of one or more elements comprising vanadium, niobium or titanium. Independent claims are included for: (1) a flat rolled steel product made of the steel, comprising 30-100% of martensite, tempered martensite or bainite and residual quantity of austenite; and (2) making the flat rolled steel products, comprising melting composite molten steel, producing an starting product for subsequent hot rolling, in which the molten steel is poured into a strand of which at least a slab or a thin slab partitioned as a starting material for hot rolling, or a cast strip provided as a starting material for hot rolling, heat treating the starting product at a hot rolling start temperature of 1000-1150[deg] C, hot rolling the starting product to a hot strip with a thickness of at most 2.5 mm, where the hot rolling is performed at 800-1050[deg] C, coiling the hot strip into a coil at a coiling temperature of = 700[deg] C, and optionally annealing the hot strip at 250-950[deg] C, cold rolling the annealed hot strips in one or more steps to a cold-rolled strip with a thickness of at most 60% of the thickness of the hot strips, annealing the cold-rolled strip at 450-950[deg] C, coating the surface of the hot strip or cold-rolled strip with a metallic corrosion protective coating, and coating the surface of the hot strip or the cold strip with an organic coating. Die vorliegende Erfindung betrifft einen Stahl mit einer mindestens 4 % betragenden Bruchdehnung A80 und einer 900 - 1500 MPa betragenden Zugfestigkeit Rm, der sich durch eine kostengünstige Herstellbarkeit auszeichnet und gleichzeitig hohe Bruchdehnungswerte und damit einhergehend eine deutlich verbesserte Umformbarkeit besitzt. Zu diesem Zweck enthält der Stahl erfindungsgemäß neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) C: bis zu 0,5 %, Mn: 4 - 12,0 %, Si: bis zu 1,0 %, Al: bis zu 3,0 %, Cr: 0,1 - 4,0 %, Cu: bis zu 2,0 %, Ni: bis zu 2,0 %, N: bis zu 0,05 %, P: bis zu 0,05 %, S: bis zu 0,01 % besteht, sowie optional ein Element oder mehrere Elemente aus der Gruppe "V, Nb, Ti" enthält, wobei die Summe der Gehalte an diesen El