| 摘要 |
PROBLEM TO BE SOLVED: To provide a aluminum alloy casting by which the coarse segregation of an eutectic structure is suppressed, and the other parts can be joined by calking or the like accompanied with plastic deformation. SOLUTION: This aluminum alloy casting has a composition containing 6.5 to 8.0% Si, 0.25 to 0.45% Mg, 0.08 to 0.40% Fe, 0.001 to 0.01% Ca, <0.0015% P, 0.02 to 0.1% Ti and 0.001 to 0.01% B and containing, at need, one or two kinds of 0.05 to 0.3% Cr and 0.05 to 0.2% Mn and has a metallic structure in which the difference in the average particles size between anα-Al phase in the surface layer part from the surface to a depth of 1 mm and anα-Al phase in the central part is controlled to 50μm or less, and the maximum size of an eutectic structure is suppressed to 400μm or less. The casting is provided in such a manner that the molten metal of an aluminum alloy whose components are controlled is filled into a die at 0.05 to 0.25 m/sec and is cooled at the temperature range between a liquidus and a solidus at 20 deg.C/sec or more in a state of being applied with pressure of 30 MPa or more.
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