Tundish and continuous casting method using same

Abstract

A tundish including a weir between molten steel pouring portion and molten steel outlet port, the weir including wall portion and hood-shaped portion at upper end of wall portion surrounding molten steel pouring portion from all sides of molten steel pouring portion and extending upward from bottom of tundish, and hood-shaped portion facing molten steel pouring portion and protruding in horizontal direction, wherein weir includes one or more notches continuous from wall portion to hood-shaped portion, and includes refractory bottom surrounded by wall portion and including first porous portion, and also includes first gas inlet pipe connected to first porous portion within weir and within refractory including first porous portion, and tundish further includes bottom refractory provided with second porous portion and with second gas inlet pipe connected to second porous portion, at bottom of tundish between weir and molten steel outlet port.

1 . A tundish comprising a weir provided between a molten steel pouring portion in which a flow of molten steel poured from a ladle collides with a bottom of the tundish and a molten steel outlet port through which the molten steel flows from the tundish to a casting mold, the weir including
 a wall portion surrounding the molten steel pouring portion from all sides and extending upward from the bottom of the tundish, and   a hood-shaped portion provided at an upper end of the wall portion and protruding in a horizontal direction while facing the molten steel pouring portion, characterized in that   the weir includes one or more notches continuous from the wall portion to the hood-shaped portion, and includes a refractory bottom surrounded by the wall portion and including a first porous portion, and also includes a first gas inlet pipe connected to the first porous portion within the weir and within the refractory including the first porous portion, and   the tundish further optionally includes a bottom refractory provided with a second porous portion and with a second gas inlet pipe connected to the second porous portion, at the bottom of the tundish between the weir and the molten steel outlet port.   
     
     
         2 . The tundish according to  claim 1 , further comprising a precast refractory installed on a wall portion of the tundish and including a third gas inlet pipe connected to the first gas inlet pipe or the second gas inlet pipe or extending from the first gas inlet pipe or the second gas inlet pipe. 
     
     
         3 . A continuous casting method for producing a cast steel slab, comprising using the tundish according to  claim 1  and pouring molten steel from the tundish into a casting mold while blowing an inert gas into the molten steel from the first porous portion through the first gas inlet pipe at a flow rate R1 of the inert gas per unit area of a bottom of the weir controlled in a range of 0.02 to 1.0 NL/(s·m 2 ) to produce a cast steel slab. 
     
     
         4 . The continuous casting method according to  claim 3 , further comprising blowing an inert gas into the molten steel from the second porous portion through the second gas inlet pipe at a flow rate R2 of the inert gas per unit area of the second porous portion controlled in a range of 0.1 to 10 NL/(s·m 2 ). 
     
     
         5 . A continuous casting method for producing a cast steel slab, comprising
 using the tundish according to  claim 2  and pouring molten steel from the tundish into a casting mold while blowing an inert gas into the molten steel from the first porous portion through the first gas inlet pipe at a flow rate R1 of the inert gas per unit area of a bottom of the weir controlled in a range of 0.02 to 1.0 NL/(s·m 2 ) to produce a cast steel slab.   
     
     
         6 . The continuous casting method according to  claim 5 , further comprising blowing an inert gas into the molten steel from the second porous portion through the second gas inlet pipe at a flow rate R2 of the inert gas per unit area of the second porous portion controlled in a range of 0.1 to 10 NL/(s·m 2 ).