REFINING METHOD FOR PRIMARY-CRYSTAL SI IN HYPEREUTECTIC AL-SI ALLOY

摘要

PURPOSE:To uniformly disperse a grain refiner into the molten metal of the titled alloy by forming an undermentioned grain refiner to be held into a prescribed form in the titled method for carrying out addition by the use of a rod composed by filling a P-containing grain refiner for primary-crystal Si into an Al fine tubing. CONSTITUTION:The molten metal 12 of the hypereutectic Al-Si alloy having Si content of eutectic point or above held in a holding furnace 10 is led into a pouring spout 16, flows through the spout 16 and is poured into a casting machine 20 to produce a billet 22 continuously. The rod 26 for addition having the P-containing grain refiner for primary-crystal Si within is add to the molten metal 15 led by means of the spout 16, which is melted. At this time, this rod 26 is a one constituted by allowing the prescribed Al tubing 34 to contain the grain refiner 30 such as Cu-8%P alloy grains in a state dispersed in an Al matrix 32 or powdered Al 36. In this way, the rod 26 is easily melted in the molten metal 15 and the grain refiner 30 is rapidly dispersed and melted in the molten metal owing to its excellent wettability to the molten metal, so that yields can be improved.