FIELD: metallurgy.
SUBSTANCE: to produce a flat steel product having a yield strength of ≥ 700 MPa and a bainitic structure of ≥ 70 % by volume, the following working steps are carried out according to the invention: a) preparing a steel melt consisting of, by weight, %: C 0.05–0.08, Si 0.015–0.500, Mn 1.60–2.00, P to 0.025, S to 0.010, Al 0.020–0.050, N to 0.006, Cr to 0.40, Nb 0.060–0.070, B 0.0005–0.0025, Ti 0.090–0.130, as well as unavoidable impurities, remainder is iron, b) casting the melt to form a slab, c) reheating the slab to a temperature of 1200–1300 °C, d) rough rolling of the slab at a temperature of 950–1250 °C and overall pass reduction of at least 50 %, d) hot finish-rolling of the rough-rolled slab with a hot-rolling end temperature of 800–880 °C, e) cooling of the hot finish-rolled flat steel product within ≤ 10 s after the hot finish-rolling to 50–620 °C at a cooling rate of ≤ 40 K/s, g) coiling of the hot finish-rolled flat steel product.
EFFECT: object of the invention to specify a method by which high-strength steel sheets having mechanical properties that have been optimized with respect to use in automobile construction and likewise optimized surface characteristics can be produced in practice.
14 cl, 3 tbl
