PURPOSE: To restrain the occurrence of thermal fatigue crack, and to obtain a piston that can efficiently operate even in a high load, in a piston whose base material is Al-Si alloy casting, by applying a hot-formed body of quenched and solidified Al-Si alloy powder excellent in thermal fatigue crack resistance to the part of the combustion chamber.
CONSTITUTION: A piston 2 has a ring-shaped or cap-shaped hot-formed body 3 that is metallically joined to the base of the piston top whose base material is Al-Si alloy casting and which constitutes at least the upper peripheral part of a recessed combustion chamber 1. And the hot-formed body 3 is formed by quenching and solidifying the molten metal of Al-Si powder at a cooling rate of 100°C/sec or higher, and further by applying hot extrusion and/or hot forging to it to form a Al-Si alloy powder solidified formed body. And the piston 2 is manufactured by metallically joining the Al-Si alloy powder solidified formed body 3, that is made by forming and solidifying the quenched and solidified Al-Si alloy powder and by forming it in a ring-shape or cap-shape by means of hot extrusion or the like, to the base so as to constitute at least the upper peripheral part of the recessed combustion chamber 1 on the top of the piston.
YODA MICHIHIRO
NANJIYOU KATSUKI
SAKURADA TORU
MITSUBISHI MOTORS CORP
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