ON THE CONTINUOUS CASTING OF ALUMINIUM

Abstract

With a semi-continuous and continuous ingot casting apparatus of a very small scale (the diameter of ingots is 43mm or 47mm), the authors carried out some experiments to know how the casting conditions affect on the structure, the density and the grain size of the ingots.The apparatus we used was shown in Fig. 1. The metal melted was commercially pure aluminium.The results were as follows;(1) The columnar grain structure was obtained when the casting temperature was above 700°C, but the fine and equiaxial one was obtained below the temperature. So it may be bad practice to cast the metal from too high temperature.(2) Below the casting temperature of 700°C, the grain size diminished as the casting speed increased. But above 10cm/min of the casting speed, we obtained the structure of oriented very fine grains. The density diminished as the speed increased.(3) To increase the casting speed over 10cm/min, the out-spraying of water was needed. The surface of ingot which were cast with the out-spraying was very good, so in practice the outspraying may be necessary.(4) For the material of the mould, copper was better than iron or graphite. The ingots cast in copper mould had good surface and the casting operation was easy.(5) The length of mould did not affect the structure but the casting operation became easy when the length was short, for the friction between the ingot and the mould was little.(6) The friction between the ingot and the mould may be thought one important problem, so some researches on lubricants for this purpose must be carried out.