Process for Producing Steel Long Products by Continuous Casting and Rolling

Abstract

In a process for producing steel long products by continuous casting of steel to form billet and bloom strands ( 5 ) and subsequent rolling of said billet and bloom strands, the liquid steel is cast in a continuous-casting permanent mould ( 3 ). The cast billet and bloom strands ( 5 ) are fed substantially without subsequent heating directly to a roll train ( 20 ). This makes the design of the plant more simple, and more cost-effective operation is made possible.

1 . A process for producing steel long products by continuous casting of steel to form billet and bloom strands and subsequent rolling of these billet and bloom strands to form the long products, such as steel bars or wire, whereby the liquid steel being cast into a continuous casting permanent mould, characterised in that the cast billet respective bloom strands are fed directly to a roll train substantially without any subsequent heating. 
     
     
         2 . The process according to  claim 1 , characterised in that the cast billet strands form a substantially quadruple round format. 
     
     
         3 . The process according to  claim 2 , characterised in that the rounding with the quadruple round format is chosen corresponding to the format such that with a sufficiently high casting speed a strand with temperature distribution required for rolling is produced which can be rolled directly without any active subsequent heating. 
     
     
         4 . The process according to  claim 1 , characterised in that the cast billet strands are substantially circular in form. 
     
     
         5 . The process according to  claim 1 , characterised in that the continuous casting permanent mould forms a mould cavity open on both sides, the mould cavity having on the end of the continuous moulding permanent mould on the pouring in side, along a circumferential line of its cross-section, at least two circumferential sections which each define a cross-sectional enlargement of the mould cavity in relation to the corresponding circumferential sections of the mould cavity cross-section on the end of the permanent mould on the strand outlet side, in the form of bulges, and curvature heights of the bulges decrease in the direction of travel of the strand such that during the casting operation a strand shell forming in the mould cavity deforms upon passing through the permanent mould and in this way guarantees rapid and even cooling and homogeneous temperature distribution along the strand circumference. 
     
     
         6 . The process according to  claim 1 , characterised in that the continuous casting speed is at least 4.2 m/min. 
     
     
         7 . The process according to  claim 1 , characterised in that at the discharge of the intermediate vessel located above the permanent mould an adjustment device, preferably a slide closure, is provided for the purpose of precise regulation of the molten steel to be cast into the permanent mould, regulation of the filling level of the molten mass in the permanent mould being implemented dependently upon the inlet speed into the first roll stand of the roll train, and the regulating device being correspondingly regulated. 
     
     
         8 . The process according to  claim 1 , characterised in that commercial grade and concrete steel are used. 
     
     
         9 . The process according to  claim 1 , characterised in that quality steel is used. 
     
     
         10 . A continuous casting permanent mould for the process according to  claim 1 , characterised in that the circumferential line of a polygonal, preferably quadrangular mould cavity cross-section has on the pouring in side between all of the corners circumferential sections with cross-sectional enlargements of the mould cavity in the form of bulges, and the curvature heights of the bulges decrease on all of the circumferential sections in the direction of travel of the strand, at least along a partial length of the mould cavity. 
     
     
         11 . The continuous casting permanent mould according to  claim 10 , characterised in that the mould cavity cross-section of the continuous casting permanent mould substantially forms a quadruple round format which is quadratic or rectangular in form, but is provided in the corner regions with radii. 
     
     
         12 . The continuous casting permanent mould according to  claim 11 , characterised in that with the continuous casting permanent mould, on the strand outlet side, the radii in the corner regions are approximately 20 to 40 mm with a thickness or width of the mould cavity cross-section of 120 to 180 mm.