| 摘要 |
PURPOSE:To decrease the amt. of the surface to be machined and to improve the yield of a product by casting continuously aluminum (alloy) in such a way that the content of boron and a cooling rate maintains a specific relation. CONSTITUTION:Aluminum or an aluminum alloy contg. boron is melted. The molten aluminum or aluminum alloy is then continuously cast at the above-mentioned relation between the content B (ppm) of boron and a cooling rate R ( deg.C/sec) which is so controlled as to be maintained within the range enclosed by the straight lines connecting the points a(B=3, R=2.7), b(B=25, R=1.8), c (B= 25, R=5), d(B=3, R=11) shown in the figure. The formation of the fir wood like structure in the casting ingot is obviated by the above-mentioned method, by which the amt. of the surface to be machined is reduced and the yeild of the product is improved. |
