Numerical Simulation Research and Application of Convex Roll for Efficient Soft Reduction of Continuous Casting Slab

Soft reduction plays an important role in the internal quality control during the production of the mid-thick slab, but it can also lead to cracks. Convex rolls can reduce the supporting role of the slab shell, improve the reduction efficiency, reduce cracks and segregation problems, which need no equipment upgrades, and can also reduce equipment wear. Through finite element numerical simulation, the soft reduction of Q345 and 45# steel mid-thick slab with 220 mm*1820 mm and 250 mm*2000 mm sections were studied, respectively, and industrial tests and applications were carried out. After adopting the convex roll, the maximum equivalent stress at the edge can be reduced by 31.05 and 5.48 pct, and the maximum total strain can be reduced by 14.3 and 27.9 pct, respectively, compared with the calculation results of the flat roll, which can improve segregation and cracks. The optimum parameters of the convex roll are determined by numerical simulation, laboratory, and industrial experiments. For the two sections, the optimum platform height is 2.5 mm, the length is 1620 and 1700 mm, and the connection is an arc, whose length is 55 and 60 mm. The numerical simulation results indicated that the convex roll can increase the deformation in the middle of the slab, and the reduction amount efficiency can maximum increase by 15.10 pct. The experimental results show that the convex roll soft reduction is better efficient in improving the segregation problems, which can maximum reduce the carbon segregation index by about 31.97 pct. The industrial application results evidenced that the single-segment reduction of the mid-thick slab of the convex roll can completely replace the conventional multi-segment reduction, and the surface crack rate reduced by 9.67 to 5.00 pct after the convex roll was applied.