Abstract: A cold-rolled flat steel product may have a yield strength Rp0.2 of not more than 320 MPa, a fracture elongation A80 of at least 20% and a microstructure having by percent area 62%-82% ferrite, 10%-30% martensite, 1.5%-8% residual austenite, and a sum total of not more than 10% other microstructure constituents. The flat steel product may comprise a steel alloy containing in percent by weight 0.06%-0.1% C; 0.15%-0.4% Si; 1.5%-2% Mn; 0.2%-0.5% Cr; not more than 0.1% Al; wherein the sum total of C, Si, Mn, and Cr is at least 2.3% and not more than 2.8%; wherein the sum total of Si and Al is not more than 0.4%; not more than 0.03% P; not more than 0.006% S; not more than 0.008% N; unavoidable impurities including not more than 0.0006% B, not more than 0.02% V, and not more than 0.01% each of Nb and Ti, and not more than 0.1% each of Mo, Ni, and Cu; as well as iron. For production of such a flat steel product, a cold-rolled flat steel product may first be produced and then brought to 760-860° C.

Abstract: A cold-rolled flat steel product may have a yield strength Rp0.2 of not more than 320 MPa, a fracture elongation A80 of at least 20% and a microstructure having by percent area 62%-82% ferrite, 10%-30% martensite, 1.5%-8% residual austenite, and a sum total of not more than 10% other microstructure constituents. The flat steel product may comprise a steel alloy containing in percent by weight 0.06%-0.1% C; 0.15%-0.4% Si; 1.5%-2% Mn; 0.2%-0.5% Cr; not more than 0.1% Al; wherein the sum total of C, Si, Mn, and Cr is at least 2.3% and not more than 2.8%; wherein the sum total of Si and Al is not more than 0.4%; not more than 0.03% P; not more than 0.006% S; not more than 0.008% N; unavoidable impurities including not more than 0.0006% B, not more than 0.02% V, and not more than 0.01% each of Nb and Ti, and not more than 0.1% each of Mo, Ni, and Cu; as well as iron. For production of such a flat steel product, a cold-rolled flat steel product may first be produced and then brought to 760-860° C.

Abstract: The invention relates to a steel and to a flat steel product produced therefrom that have optimized mechanical properties and at the same time can be produced at low cost, without having to rely for this on expensive alloying elements that are subject to great fluctuations with regard to their procurement costs. The steel and the flat steel product have for this purpose the following composition according to the invention (in % by weight): C: 0.12-0.18%; Si: 0.05-0.2%; Mn: 1.9-2.2%; Al: 0.2-0.5%; Cr: 0.05-0.2%; Nb: 0.01-0.06%; the remainder Fe and impurities that are unavoidable for production-related reasons, which include contents of phosphorus, sulfur, nitrogen, molybdenum, boron, titanium, nickel and copper as long as the following respectively apply for their contents: P: ?0.02%, S: ?0.003%, N: ?0.008%, Mo: ?0.1%, B: ?0.0007%, Ti: ?0.01%, Ni: ?0.1%, Cu: ?0.1%. Similarly, the invention relates to a method for producing a flat steel product that consists of a steel according to the invention.