Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
RESEARCH ON THE NON-METALLIC INCLUSIONS OF KILLED STEEL (III)
Yosaku KoikeIechika InuzukaTakeo Horigome
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1957 Volume 43 Issue 2 Pages 122-126

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Abstract

(1) The relation between the cooling conditions of ingot bottom and the flow-up speed of macroscopic inclusions were researched. Here the experimentally designed 500kg ingot molds whose bottoms were lined with refractories were compared with the normal molds by investigation of experimental ingots or forged billets. Al additions in the ladle were 200-500g/t. The results obtained were as follows.
(i) The streak seams were far less found in the bottoms of the ingots which were made with the special molds using refractories at their bottoms than in those with normal molds.
(ii) When Al additions in the ladle were 210g/t, Fe-Mn-Al silicate-seams with high Al2O3-content were found in the sample-ingots, but the seams of Al2O3-type increased by addition of 500g/t Al.
These silicate-seams presumably had been molten in the mold because of the appearance of almost perfect sphere, while Al2O3-seams (cubic crystals) had been at solid state in the molten steel.
(iii) The relations between the crystal structure of ingot and the seams-distribution were not clearly recognized.
(iv) A small secondary pipe was found in the ingot bottom which was made by the special mold.
(2) The relations between the crystal structure of ingots and the seams-distribution in 5 ton practical ingot (top-poured) were investigated.
(i) The seams almost never occurred in the columnar crystals.
(ii) The seams were found at random within the end of columnar crystals at the ingotbottom.
These inclinations of seams-distribution presumably were as much influenced by other causes as by crystal structure.
(iii) The group seams which were very rarely found in the ring ghost were recogniged to have been influenced by segregation at the solidification of the ingot.

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© The Iron and Steel Institute of Japan
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