Process and related plant for producing steel strips with solution of continuity

Abstract

A process for manufacturing steel strips with solution of continuity. The steps of the process include a continuous casting step for thin slabs with a high “mass flow,” a shearing step and subsequent heating in furnace, followed by a multiple stand rolling step with the average temperature of the product at the inlet of the rolling mill being higher than the surface temperature, which is equal to at least 1100° C., lower than that measured in the inner central area by about 100° C. A plant is also described for the accomplishment of such process where at the inlet of a furnace, possibly of the induction type, combined with a temperature maintaining tunnel a shear is provided for cutting into pieces a slab coming from continuous casting with the distance between the outlet of the continuous casting and the inlet into the finishing rolling mill is not greater than 100 m.

1 . A plant for production of steel strips from thin slabs having thickness comprised between 45 and 110 mm coming from continuous casting, comprising:
 a shear cutting a casting product, which is formed with a solution of continuity, into the slabs;   a multiple stand finishing rolling mill located downstream of the shear, a distance between an outlet of the continuous casting and an inlet to the rolling mill being not greater than 100 m;   at least one heating furnace located downstream of the shear and upstream of the multiple stand finishing rolling mill; and   a descaler arranged between the at least one furnace and the rolling mill,   wherein one of the at least one furnace is an induction furnace having a sufficiently low working frequency to heat a core of the slab and to substantially maintain a same temperature difference between an inside and an outside of the slab from an end of the induction furnace to an inlet of a first rolling stand of the finishing rolling mill, and   whereby an average temperature of each slab is higher than a surface temperature of each slab, which is equal to or higher than 1100° C. and the average temperature at the core is at least 100° C. higher than the surface temperature of each slab.   
     
     
         2 . The plant according to  claim 1 , further comprising a second furnace, which is a tunnel furnace that is heated by gas. 
     
     
         3 . The plant according to  claim 1 , wherein the plant has only one furnace and the furnace is an induction type furnace. 
     
     
         4 . The plant according to  claim 1 , further comprising a temperature maintaining tunnel in combination with the induction furnace, upstream and/or downstream thereof, having a length to keep a total distance between the continuous casting and the finishing rolling mill not greater than 100 m, suitable for limiting the thermal losses. 
     
     
         5 . The plant according to  claim 4 , wherein the tunnel is formed by roller tables having insulating panels. 
     
     
         6 . The plant according to  claim 4 , wherein the tunnel has gas burners and/or electrical resistors. 
     
     
         7 . The plant according to  claim 4 , wherein the induction furnace is placed immediately upstream of the descaler. 
     
     
         8 . The plant according to  claim 4 , wherein the induction furnace is placed immediately downstream of the shear. 
     
     
         9 . The plant according to  claim 3 , further comprising intermediate cooling and/or heating means among the rolling mill stands.