Patent ID: 9144839
Filing Date: 2015-09-29
Classification: B21B,B22D,C22C,F16L,Y10T

Abstract:
1. A method for producing microalloyed tubular steel in a combined casting-rolling installation using a continuous casting machine featuring a mold and a strand guide, a single-stand or multi-stand roughing train, an induction furnace, a descaling device, a multi-stand finishing train, a cooling section and a storage device, said method comprising: casting a steel melt in the mold to form a partially solidified thin slab strand, the steel melt consisting of 0.04-0.05% C, 1.3-1.5% Mn, 0.035-0.05% Nb, 0.035-0.06% V, 0.2-0.4% Cr, 0.2-0.3% Si, 0.015-0.05% Al and <0.008% N in percent by weight, the remainder consisting of Fe and unavoidable impurities; deflecting the partially solidified thin slab strand into a curved strand guide; supporting, guiding and cooling the thin slab strand in the curved strand guide; deflecting the thin slab strand into a horizontal strand guide, the thin slab strand solidifying totally either in the curved strand guide or in the horizontal strand guide to form an uncut thin slab strand; roughing the uncut thin slab strand to form a rough strip in the roughing train, the uncut thin slab strand having a core temperature at least 50° C. higher than a surface temperature of the uncut thin slab strand when the uncut thin slab strand enters the roughing train, the thin slab strand roughed in the roughing train by a total reduction factor of at least 40% with complete static recrystallization of a first microstructure occurring during the roughing; reheating the rough strip in the induction furnace to an average rough strip temperature of greater than 1000° C. to produce a reheated rough strip; descaling the reheated rough strip in the descaling device to produce a descaled rough strip; finish-rolling the descaled rough strip in a first group of rolling stands of the finishing train to form a partially finish-rolled rough strip having a second microstructure at least partially statically recrystallized following a reduction stage in the first group of the rolling stands of the finishing train; then immediately finish-rolling the partially finish-rolled rough strip in a second group of the rolling stands of the finishing train to form a finished strip in which the second microstructure does not recrystallize; cooling the finished strip in the cooling section; cutting and storing the finished strip in the storage device.