HYPER-EUTECTIC ALUMINUM-SILICON ALLOY CAST MEMBER AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a hyper-eutectic Al-Si alloy cast member in which primary crystal Si is crystallized out at optimum particle size and optimum distribution density without excessively increasing the holding temp. and excellent in wear resistance and workability. SOLUTION: A hyper-eutectic Al-Si alloy molten metal contg. 14 to 25% Si and 0.001 to 0.02% P is prepd., the hyper-eutectic Al-Si alloy molten metal housed in a holding furnace at the time of casting is held in the temp. range of (24.6×Si%+324) to (24.6×Si%+354 deg.C, and the hyper-eutectic Al-Si allay molten metal is poured from the holding furnace into a mold to obtain a cast member having a cast structure in which primary crystal Si of <=18μm average particle size is crystallized out. In the casting, the cooling rate of the hyper- eutectic Al-Si alloy poured into the mold is preferably held to >=1 deg.C/sec.