Flat steel product, characterised in that it contains a steel, which consists of (in wt%) 0.1 - 0.5% C, 1.0 - 3.0% Mn, 0.9 - 1.5% Si, up to 1.5% Al, up to 0.008%, N, up to 0.020%, P, up to 0.005%, S, 0.01- 1% Cr, as well as optionally consisting of one or more of the following elements up to 0.2% Mo, up to 0.01% B, up to 0.5% Cu, up to 0.5% Ni as well as optionally consisting of in total 0.005 - 0.2% microalloying elements, selected from Ti, Nb and V, and iron as a remainder and unavoidable impurities, wherein the following applies: 75 ≤ Mn 2 + 55 * Cr / Cr ≤ 3000 where Mn is the Mn content of the steel in wt%, Cr is the Cr content of the steel in wt% and has a structure, which consists of - at least 80 area% martensite, of which at least 75 area% is tempered martensite and at most 25 area% is non-tempered martensite, - at least 5% by volume of residual austenite, - 0.5 to 10 area% ferrite and - at most 5 area% bainite, wherein in the region of the phase boundary between tempered martensite and residual martensite there is a low-Mn ferrite seam which has a width of at least 4 nm and at most 12 nm and the Mn content of which is at most 50% of the average total Mn content of the flat steel product and the flat steel product has carbides, the length of which is equal to or less than 250 nm and the flat steel product has a tensile strength of 900 to 1500 MPa, a yield strength Rp02 of more than 700 MPa, an elongation A80 of 7 to 25%, a bending angle of greater than 80°, a hole expansion of greater than 25% and a maximum deep-drawing ratio ß max , determined as disclosed in the description, for which the following applies: β max ≥ − 1.9 ⋅ 10 − 6 × R m 2 + 3.5 ⋅ 10 − 3 × R m + 0.5 where Rm is the tensile strength of the flat steel product in MPa. as well as optionally consisting of in total 0.005 - 0.2% microalloying elements, selected from Ti, Nb and V, and iron as a remainder and unavoidable impurities, wherein the following applies: 75 ≤ Mn 2 + 55 * Cr / Cr ≤ 3000 where Mn is the Mn content of the steel in wt%, Cr is the Cr content of the steel in wt% and has a structure, which consists of - at least 80 area% martensite, of which at least 75 area% is tempered martensite and at most 25 area% is non-tempered martensite, - at least 5% by volume of residual austenite, - 0.5 to 10 area% ferrite and - at most 5 area% bainite, - at least 80 area% martensite, of which at least 75 area% is tempered martensite and at most 25 area% is non-tempered martensite, - at least 5% by volume of residual austenite, - 0.5 to 10 area% ferrite and - at most 5 area% bainite, wherein in the region of the phase boundary between tempered martensite and residual martensite there is a low-Mn ferrite seam which has a width of at least 4 nm and at most 12 nm and the Mn content of which is at most 50% of the average total Mn content of the flat steel product and the flat steel product has carbides, the length of which is equal to or less than 250 nm and the flat steel product has a tensile strength of 900 to 1500 MPa, a yield strength Rp02 of more than 700 MPa, an elongation A80 of 7 to 25%, a bending angle of greater than 80°, a hole expansion of greater than 25% and a maximum deep-drawing ratio ß max , determined as disclosed in the description, for which the following applies: β max ≥ − 1.9 ⋅ 10 − 6 × R m 2 + 3.5 ⋅ 10 − 3 × R m + 0.5 where Rm is the tensile strength of the flat steel product in MPa. <EOS>