Abstract: A method for producing a cold-rolled steel strip with a yield ratio Re/Rm of at least 0.7, the cold-rolled steel product including iron, unavoidable impurities and (in wt. %) C: 0.05-0.20%, Si: 0.25-1.00%, Mn: 1.0-3.0%, Al: 0.02-1.5%, Cr: 0.1-1.5%, N: <0.02%, P: <0.03%, S: <0.05% and optionally one or more of Ti, Mo, Nb, V, and B, Ti: up to 0.15%, Mo: <2%, Nb: <0.1%, V: <0.12%, and B: 0.0005-0.003%. The cold-rolled flat steel product undergoes heat treatment for 4.5-24 hours at a temperature of 150-400° C. Also, a cold rolled flat steel product discussed above having a structure including at least two phases, selected from (in vol. %) at least 10% tempered martensite, <10% bainite, <10% residual austenite and remainder ferrite, a yield ratio of at least 0.7, a tensile strength of ?750 MPa and a hole expansion of at least 18%.

Abstract: A complexly formed steel component may have a tensile strength Rm of greater than 1200 MPa and an elongation at break A50 of greater than 6%. Example methods for producing such components comprise providing a flat steel product, which in addition to iron and unavoidable impurities, contains in percent by weight 0.10-0.60% C, 0.4-2.5% Si, up to 3.0% Al, 0.4-3.0% Mn, up to 1% Ni, up to 2.0% Cu, up to 0.4% Mo, up to 2% Cr, up to 1.5% Co, up to 0.2% Ti, up to 0.2% Nb, and up to 0.5% V. At least 10% by volume of a microstructure of the flat steel product may consist of residual austenite comprising globular residual austenite islands with a grain size of at least 1 ?m. Before being cooled, the flat steel product may be heated to a forming temperature of 150-400° C. and formed into a component with a degree of forming that is at most equal to uniform elongation Ag.

Abstract: A method for producing a cold-rolled steel strip with a yield ratio Re/Rm of at least 0.7, the cold-rolled steel product including iron, unavoidable impurities and (in wt. %) C: 0.05-0.20%, Si: 0.25-1.00%, Mn: 1.0-3.0%, Al: 0.02-1.5%, Cr: 0.1-1.5%, N: <0.Q2%, P: <0.03%, S: <0.05% and optionally one or more of Ti, Mo, Nb, V, and B, Ti: up to 0.15%, Mo: <2%, Nb: <0.1%, V: <0.12%, and B: 0.0005-0.003%. The cold-rolled flat steel product undergoes heat treatment for 4.5-24 hours at a temperature of 150-400° C. Also, a cold rolled flat steel product discussed above having a structure including at least two phases, selected from (in vol. %) at least 10% tempered martensite, <10% bainite, <10% residual austenite and remainder ferrite, a yield ratio of at least 0.7, a tensile strength of ?750 MPa and a hole expansion of at least 18%.

Abstract: A complexly formed steel component may have a tensile strength Rm of greater than 1200 MPa and an elongation at break A50 of greater than 6%. Example methods for producing such components comprise providing a flat steel product, which in addition to iron and unavoidable impurities, contains in percent by weight 0.10-0.60% C, 0.4-2.5% Si, up to 3.0% Al, 0.4-3.0% Mn, up to 1% Ni, up to 2.0% Cu, up to 0.4% Mo, up to 2% Cr, up to 1.5% Co, up to 0.2% Ti, up to 0.2% Nb, and up to 0.5% V. At least 10% by volume of a microstructure of the flat steel product may consist of residual austenite comprising globular residual austenite islands with a grain size of at least 1 ?m. Before being cooled, the flat steel product may be heated to a forming temperature of 150-400° C. and formed into a component with a degree of forming that is at most equal to uniform elongation Ag.

Abstract: A cold-rolled flat steel product where Rm?1400 MPa and A80?5% and also a method for producing such product. The product includes, in addition to Fe and unavoidable impurities (in wt. %), 0.10-0.60% C, 0.4-2.5% Si, ?3.0% Al, 0.4-3.0% Mn, ?1.0% Ni, ?2.0% Cu, ?0.4% Mo, ?% Cr, ?1.5% Co, ?0.2% Ti, ?0.2% Nb, ?0.5% V. The microstructure includes (in vol. %) ?20% bainite, 10-35% residual austenite and martensite as the remainder. A slab, thin slab or a cast strip having said composition, is hot-rolled to form hot strip with a hot-rolling end temperature ?830° C., coiled at a coiling temperature ?560° C., cold-rolled at ?30% reduction and heat-treated by firstly being heated to an annealing temperature ?800° C., then being cooled at a cooling rate of ?8° C./s to a holding temperature of 470° C. to greater than the martensite start temperature and then being held at the holding temperature until at least 20 vol. % bainite is present in the microstructure.

Abstract: A hot-rolled flat steel product having a product of Rm and A80 of ?18,000 MPa*%, a composition including (in wt.) C:0.10-0.60%, Si:0.4-2.0%, Al:?2.0%, Mn:0.4-2.5%, Ni:?1%, Cu:?2.0%, Mo:?0.4%, Cr?2%, Ii:?0.2%, Nb:?0.2%, V:?0.5%, remainder Fe and unavoidable impurities, and a microstructure of bainite and residual austenite, wherein the microstructure includes ?60 vol.% bainite, and wherein at least some of the residual austenite is in block form and ?98% of the residual austenite blocks have a size of ?5 ?m. Also, a method where a slab, thin slab or a cast strip having the aforementioned composition is hot-rolled at a hot-rolling end temperature of ?880° C., cooled with a cooling rate of ?5° C./s to a coiling temperature between the martensite start temperature and 600° C., coiled, and cooled in the coil while being held between the bainite start temperature and the martensite start temperature until ?60 vol.% of the hot strip microstructure is bainite.