US 11,987,859 B2
Energy-efficient production of a ferritic hot-rolled strip in an integrated casting-rolling plant
Heinz Fürst, Gallneukirchen (AT); Simon Grosseiber, Leonding (AT); Thomas Lengauer, Weißkirchen a.d. Traun (AT); and Michael Zahedi, St. Marien (AT)
Assigned to PRIMETALS TECHNOLOGIES AUSTRIA GMBH, (AT)
Filed by Primetals Technologies Austria GmbH, Linz (AT)
Filed on Dec. 14, 2021, as Appl. No. 17/550,028.
Claims priority of application No. 20214219 (EP), filed on Dec. 15, 2020.
Prior Publication US 2022/0186340 A1, Jun. 16, 2022
Int. Cl. C21D 9/60 (2006.01); C21D 1/42 (2006.01); C21D 8/02 (2006.01); C23G 3/02 (2006.01)
CPC C21D 9/60 (2013.01) [C21D 1/42 (2013.01); C21D 8/0205 (2013.01); C21D 8/0226 (2013.01); C23G 3/023 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A process for producing a ferritic hot-rolled strip in an integrated casting-rolling plant, comprising:
continuous casting of a liquid steel to give a strand having a slab or thin slab cross section in a continuous casting plant;
prerolling of the strand to give an intermediate strip in a multistand roughing mill;
increasing an average temperature of the intermediate strip using a plurality of inductive volume-heating modules in an induction furnace;
heating of broad sides of the intermediate strip by at least one inductive surface heating module to a surface temperature of ≥1000° C. without raising the average temperature of the intermediate strip above 990° C., wherein the at least one surface heating module is operated using an alternating current having a first frequency f1≥20 kHz;
descaling of the broad sides of the heated intermediate strip in a descaling apparatus after the heating of the broad sides;
rolling of the descaled intermediate strip to give the hot-rolled strip in a multistand finishing mill, where the descaled intermediate strip after descaling and without further cooling enters a first stand of the finishing mill with an average temperature of 775-900° C. and at least a last rolling pass in the finishing mill takes place in the ferritic temperature range of the steel;
setting of the hot-rolled strip to coiler temperature; and
winding-up of the hot-rolled strip in a coiler, wherein
the average temperature of the intermediate strip before the descaling step is in the range 875° to 990° C.