Heat transfer behavior of slab solidification in convex lens-shaped mold
The frequent occurrence of edge linear cracks with a width of 45-120 mm at the edge of wide and thick plates during rolling process is a common technical problem in the steel industry.Producing wide and thick slabs with a concave arc structure on the narrow can effectively prevent the narrow face of slab turn to the wide side dur-ing rolling process,thus it can significantly reduce the width of edge linear cracks in wide and thick plates.In order to make the wide and thick slabs with narrow concave curved faces,a mold with convex curved structure narrow face copper plates(called a convex lens-shaped mold)was designed.Based on this,a 3D coupled thermo-mechanical fi-nite element model for the 1/4 slab-mold system was established,and the laws of dynamic deformation of slab shell,the distribution of heat transfer medium in the gap between slab and copper plate,and the temperature evolution of solidified slab and the copper plate in the convex lens-shaped mold and a traditional mold were comparatively ana-lyzed.The results show that the maximum interface gap of slab-mold around mold wide face corner is 1.26 mm at the mold exit in the convex lens-shaped mold.As a result,the maximum thickness of the air gap is 0.71 mm,and the thickest slag film in the off-corner area is about 1.13 mm.As to the narrow face,the maximum interface gap forms at the mold corner at the position of 500 mm below meniscus.The maximum thickness is 1.40 mm.Accord-ingly,the maximum thickness of the air gap is 0.53 mm at the corner,and the thickest slag is 1.35 mm in the off-corner area.Compared with the traditional mold,the maximum interface gap in the wide and narrow corners of con-vex lens-shaped mold reduce by 0.29 mm and 0.33 mm than that of in traditional mold,respectively.Also,the maximum thicknesses of the air gap and slag film reduce by 0.23 mm,0.18 mm and 0.35 mm and 0.34 mm,respec-tively.As a result,the distribution ranges of high temperature areas in the wide and narrow off-corner of the slab reduce by 36 mm and 17 mm,respectively,and the maximum temperatures reduces by 35 ℃ and 44 ℃ correspond-ingly.It improves the uniformity of the slab heat transfer.Moreover,the temperature distribution at position of narrow face around the meniscus becomes more uniform,and the maximum temperature reduces by 15 ℃ since the homogenizing water slit design in convex lens-shaped mold compared to the traditional mold.
edge linear crackconvex lens-shaped moldconcave slabair gap and mold slag distributioncontinu-ous casting
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