Method for reducing edge serration defects in thin slab

Abstract

Disclosed herein is a method for reducing edge serration defects in a thin slab, including: reheating a thin slab having an alloy composition including carbon (C), niobium (Nb), aluminum (Al), iron (Fe) and inevitable impurities to uniformalize the thin slab into an austenite structure; controlling precipitates that occur in the reheated thin slab by controlling an temperature of the thin slab discharged from a heat-treatment furnace at a temperature at which niobium carbide (NbC) start to precipitate; and hot-rolling the thin slab. The method is advantageous in that the temperature of a thin slab discharged from a heat-treatment furnace is controlled, so that the edge serration defects in the thin slab can be reduced, thereby improving the productivity of the thin slab.

1 . A method of producing a steel sheet, the method comprising:
 providing a steel slab of an alloy composition comprising iron (Fe), carbon (C), niobium (Nb) and aluminum (Al);   rolling the steel slab into a steel sheet; and   controlling temperature of the steel slab for rolling such that niobium carbide (NbC) precipitates during rolling while inhibiting precipitation of niobium carbide.   
     
     
         2 . The method of  claim 1 , wherein controlling comprises:
 heating the steel slab, before rolling, to a temperature higher than NbC precipitation temperature of the alloy composition; and   letting the steel slab cooled to a temperature lower than the NbC precipitation temperature as the steel slab enters and is rolled.   
     
     
         3 . The method of  claim 1 , wherein providing the steel slab comprises continuously casting the alloy into the steel slab. 
     
     
         4 . The method of  claim 3 , further comprising: continuously supplying the steel slab to a roller for rolling. 
     
     
         5 . The method of  claim 4 , wherein controlling comprises heating the steel slab while being supplied for rolling to a temperature higher than NbC precipitation temperature of the alloy composition such that when the steel slab is rolled, the steel slab is cooled to a temperature lower than the NbC precipitation temperature. 
     
     
         6 . The method of  claim 1 , wherein the thin slab is reheated to be in an austenite state. 
     
     
         7 . The method of  claim 1 , wherein the carbon (C) is present in an amount of 0.20 to 0.28 wt %. 
     
     
         8 . The method of  claim 1 , wherein the thin slab is reheated in a furnace and discharged from the furnace at a temperature of 1060 to 1100° C. 
     
     
         9 . The method of  claim 1 , wherein the thin slab is reheated in a furnace and discharged from the furnace at a temperature of 1080 to 1100° C.