Method and plant for rolling hot-rolled wide strip in a CSP plant
AssigneeSMS Schloemann-Siemag Aktiengesellschaft
InventorsKarl-Ernst Hensger, Robert Davis
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Abstract
A method and a plant for rolling hot-rolled wide strip from continuously cast thin slabs of ferritic/pearlitic microalloyed structural steels with a microalloy with vanadium and/or with niobium and/or with titanium in a CSP plant or compact strip production plant, wherein the cast slab strand is supplied divided into rolling lengths through an equalizing furnace to a multiple-stand CSP rolling train and is continuously rolled in the CSP rolling train into hot-rolled wide strip, is then cooled in a cooling stretch and is reeled into coils. For achieving optimum mechanical properties in hot-rolled wide strip by thermomechanical rolling, a controlled structure development is carried out when the thin slabs travel through the CSP plant.
Claims7
In a method of rolling hot-rolled wide strip from continuously cast thin slabs of ferritic/pearlitic microalloyed structural steels with a microalloy with at least one of vanadium and niobium and titanium in a CSP plant, wherein a cast slab strand is divided into rolling lengths and is supplied through an equalizing furnace to a multiple-stand CSP rolling train and is continuously rolled in the CSP rolling train into hot-rolled wide strip, is cooled in a cooling stretch and is reeled into coils, the improvement comprising, for achieving optimum mechanical properties in hot-rolled wide strip by thermomechanical rolling, carrying out a controlled structure development as the thin slabs travel through the CSP plant, the method comprising the steps of:
- (a) changing the cast structure by adjusting defined temperature and shape changing conditions during a first transformation, wherein the temperature is above the recrystallization stop temperature, so that a complete recrystallization of the cast structure takes place at least one of during and after the first deformation and prior to a beginning of a second deformation step;
- (b) carrying out a deformation in the last roll stands at temperatures below the recrystallization stop temperature, wherein the deformation is not to drop below a quantity of 30% and a final rolling temperature is near the austenite/ferrite transformation temperature;
- and
- (c) carrying out a controlled cooling of the hot-rolled strips in the cooling stretch, wherein the polymorphous transformation of the austenite takes place at a temperature between the austenite/ferrite transformation temperature and the bainite start temperature.
A plant for rolling hot-rolled wide strip from continuously cast thin slabs of ferritic/pearlitic microalloyed structural steels with a microalloy with at least one of vanadium and niobium and titanium in a CSP plant, wherein a cast slab strand is divided into rolling lengths and is supplied through an equalizing furnace to a multiple-stand CSP rolling train and is continuously rolled in the CSP rolling train into hot-rolled wide strip, is cooled in a cooling stretch and is reeled into coils, wherein the multiple-stand rolling train comprises at least a first and a second deforming stand, wherein the multiple-stand rolling train is configured such that defined shape changing conditions of the first deforming stand are adjustable such that a recrystallization of the cast structure of the thin slab takes place at least one of during and immediately following the first deformation, and wherein a sufficiently great distance exists between the first deforming stand and the second deforming stand, so that, depending on the recrystallization time, the recrystallization is concluded when the second deformation begins.
Dependencies are inferred from the claim text.