| 摘要 |
PURPOSE:To form fine crystal grain structure and to obtain a high-quality ingot having the fine crystal grain structure by successively scanning the top surface of the ingot at a specific area rate and forming molten pools as small as possible. CONSTITUTION:Raw material lumps 10 for melting are melted by electron beams 18, 19 while the lumps are supplied from above to form the ingot 12. The top surface of the ingot 12 is successively scanned at <=5% area rate while said surface is locally melted. The electron beams are respectively deflected 18, 109 by a deflecting coil 20 to melt the surface of the ingot 12 and to form the molten pools 16, 17. The molten pools 16 and 17 and parted form each other and are not continuous. Since the molten pools which are melting parts are successively scanned and moved, solidification is quickly executed and since the molten pools are small, the workability of the fine crystal grain structure in a post stage is improved.
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