| 摘要 |
PURPOSE: A producing method for a billet without cracks is provided to regularly solidify the billet by giving proper roughness to the surface of a twin roll. CONSTITUTION: In a twin roll type sheet producing method, a sheet is produced by supplying molten steel through a nozzle between both rolls of a twin roll (40). Many dimples (72) are formed on the surface of the twin roll. The dimple has 0.2 to 1.0mm of the diameter and 20 to 100 micrometers of the depth and a distance between the dimples is less than 0.1mm. Then, molten steel passes through the twin roll under nitrogen gas atmosphere. Furthermore, the dimple is in a hemispheric shape and the area rate of the dimple is more than 70%. Therefore, in a twin roll type sheet producing line, a billet is produced without cracks.
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