| 摘要 |
PURPOSE:To prevent surely the surface crack of a continuously cast bilet by indenting continuously a projection at high-speed periods to the surface of the steel ingot under progression of solidification to the adequate depth thereby applying plastic strain to the surface layer part of the billet in the front stage of a straightening stage. CONSTITUTION:In this continuous casting method, the molten steel L in a ladle 1 is cast through a tundish 2 into a mold 3 and a solidified shell S is grown by cooling grid 4 and guide rolls groups 5; further the ingot strightened horizontally by straightening rolls (not shown in figure) is drawn. The projection of a working tool 7 is intended continuously to the surface of the shell S at >=50 times/sec period to 1-5mm. indentation depth by a surface working tool 6 consisting of the 1st driving mechanism 9 which advances and retreats the tool 7 to and from the shell S, the 2nd driving mechanism 10 which advances and retreats the tool 7 in the drawing direction of the billet and a control mechanism 11 which makes the combined movement thereof in the fore stage of the straightening stage of the above-mentioned casting method. About >=5% plastic strain is thus applied to the surface layer part of the shell S, by which the carbonitride is condensed and coarsened and the cracking in the stage of deformation by the straightening is surely prevented. |
