Internal combustion engine cylinder head composed of an aluminium alloy casting

摘要

Disclosed are: a casting aluminum alloy that is excellent in elongation as alternative properties of a high cycle fatigue strength and a thermal fatigue strength and is suitably usable for a casting for which both of the excellent high cycle fatigue strength and the excellent thermal fatigue strength are required, for example, an internal combustion engine cylinder head; a casting made of the aluminum alloy; a manufacturing method of the casting; and further, an internal combustion engine cylinder head composed of the aluminum alloy casting and manufactured by the manufacturing method of the casting. The casting aluminum alloy contains, in terms of mass ratios, 4.0 to 7.0% of Si, 0.5 to 2.0% of Cu, 0.25 to 0.5% of Mg, no more than 0.5% of Fe, no more than 0.5% of Mn, and at least one component selected from the group consisting of Na, Ca and Sr, each mass ratio of which is 0.002 to 0.02%.