PURPOSE: To prevent generation of fir-like structure in the bottom of a casting ingot in the stage of casting continuously an Al alloy for rolling which crystallizes an Al-Fe intermetallic compd. in the casting ingot by controlling the content of B in the bottom part of the casting ingot and cooling rate in the initial period of casting within a specific range.
CONSTITUTION: A dummy molten metal 3 is put onto a bottom plate 2 disposed on the bottom of a water-cooled pattern 1 in the initial period of casting and normal continuous casting is started just before the top surface thereof solidifies in the stage of casting continuously an Al-Fe alloy added with B. The quick cooling of the molten Al alloy by the bottom plate 2 is obviated by the presence of the dummy metal 3 and therefore no gap is formed between the plate 2 and the casting ingot. The control of the cooling rate in the part at least ≥100mm above the bottom of the casting ingot to the relation between the content of B and the cooling rate in the region (x) enclosed by the lines connecting the points a, b, c, d in the figure 2 is thus made possible. The formation of the fir-like structure in the bottom of the casting ingot of such Al alloy is obviated and the formation of different color tones in the stage of anodizing treatment is prevented.
INOUE TOSHINORI
NAKAMURA EIJI
INUMARU SUSUMU
ADACHI SHIYUNSUKE
| JPS6426788A | 1989-01-30 |
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