| 摘要 |
PURPOSE:To remove the defective part after detecting it by the ultrasonic flaw detector, and to improve the yield of the steel billet, by first blooming the steel ingot prepared by the ingot molding process employing the surface plate possessing specified cavity-breadth/ingot-breadth ratio, and next, by shearing off the bottom part so as to leave the unbonded deepest part. CONSTITUTION:The ingot mold is placed upon the surface plate 1 possessing the 0.5 or large cavity breadth ratio (defined as the ratio, the surface plate's cavity- breadth L/ingot-breadth), and the molten steel is poured into this mold; after that, the mold is removed away. Thus prepared steel ingot is processed by the blooming mill; hereby, the mechanical pipe (unbonded defect) 6 is surely generated at the middle of breadth of the steel billet 7. Hence, the pipe 6 is cut off depending on the reference that permits the tip of the pipe 6 to be surely left in the bottom of the steel billet 7. Hereupon, this bloomed steel billet is processed by the continuous hot rolling according to the conventional method; and the remained pipe 6 is detected by the ultrasonic flaw detector at the inlet of the pickling process, for example; and the defective steel strip part is cut off depending on this detection. Hereupon, since such unstable element as both of far and near blind zones of the probe disappears, the defective part at the middle of the steel strip can be surely detected. |
