Method for producing a dual-phase steel strip in a combined casting and rolling system, a dual-phase steel strip produced by means of the method, and a combined casting and rolling system

A method for producing a dual-phase steel strip in a combined casting and rolling plant,

• wherein the combined casting and rolling plant comprises a finish-rolling train having a first stand group with at least one first finish-rolling stand and a second stand group with at least one stand cooler, and a cooling section having a first cooling-section group and a second cooling-section group,
• wherein a hot prerolled strip is fed to the first stand group of the finish-rolling train and finish-rolled by the first stand group of the finish-rolling train to afford a finish-rolled strip,
• wherein, directly after the finish-rolling of the finish-rolled strip, the finish-rolled strip is fed to the second stand group and, in the second stand group, the finish-rolled strip is force-cooled to a second outlet temperature (TA2) while maintaining a thickness of the finish-rolled strip, in such a way that the finish-rolled strip has a predominantly austenitic microstructure when it leaves the second stand group,
• wherein the finish-rolled strip, which has been cooled to the second outlet temperature (TA2), is fed to the first cooling-section group,
• wherein forced cooling of the finish-rolled strip in the first cooling-section group is deactivated and the finish-rolled strip is transported in the first cooling-section group to the second cooling-section group,
• wherein, during the transport, a ferritic and austenitic microstructure predominantly forms in the finish-rolled strip,
• wherein, in the second cooling-section group, the finish-rolled strip is force-cooled to a fourth outlet temperature (TA4) in such a way that, after leaving the second cooling-section group, the finish-rolled strip has a dual-phase microstructure of martensite and ferrite.