To provide a piston made of an Al alloy with a low Ca content, which inexpensively and reliably has reduced the Ca content.
The piston is made of the Al alloy with the low Ca content, which contains 0.002 mass% or less Ca. The piston uses an Al alloy ingot comprising, by weight ratio, 0.003 mass% or more Ca, 4-25 mass% Si, 7 mass% or less Cu, 1.5 mass% or less Fe, 7 mass% or less Ni and 0.2 mass% or less Mg.The method for manufacturing the piston comprises: the ingot-making step of melting the Al alloy raw material having the above composition; the deoxidization treatment step of removing nonmetallic inclusions such as an oxide in the molten metal; the molten metal-holding step of reducing the Ca content by exposing the surface of the molten metal to atmospheric air for 20 minutes or longer; then the Mg-adding step of adding a desired amount of Mg into the molten metal; and the casting step of casting the molten metal into a mold having a desired form.
HOJO HIROSHI
SUGIMOTO YOSHIHIKO
UEDA ISAMU
IWABORI HIROAKI
HAYASHI SOICHI
UCHIDA KUNIHIKO
TAKAGI KATSUMI
NARUSAWA MASARU
NAKAJIMA RYOICHI
TOYOTA MOTOR CORP
AISIN SEIKI
ART METAL MFG CO LTD
Tamiwa Iwakura