| abstract |
(57) [Object] To provide an aluminum alloy piston exhibiting excellent fatigue strength even in a high temperature range of 200 to 250 ° C. This piston made of aluminum alloy has Si: 11 to 13%, Fe: 0.2 to 1.2%, C after forging. u: 3.5 to 4.5%, Mn: 0.2 to 0.5%, M g: 0.3 to 1.0%, Ti: 0.01 to 0.2%, B: 0.0002-0.02%, P: 0.005-0. Containing 0.2%, Ca is regulated to 0.005% or less, Si and intermetallic compounds crystallized during casting are uniformly dispersed in a matrix having an average particle diameter of 5-35 μm after forging, and the gas content is 0.25 cc / It has regulated forged tissue below 100 g-Al, 0 inclusions average number in the ingot stage in K 10 value. It is regulated to not more than 01 pieces / cm 2 and is formed by forging. |