| 摘要 |
PROBLEM TO BE SOLVED: To obtain an aluminum alloy casting exhibiting excellent proof stress and elongation in an as-cast state. SOLUTION: This aluminum alloy casting has a composition which contains, by weight ratio, 4-8% Si, 0.4-1.0% Cu, 0.2-0.4% Mg, 0.05-0.3% Fe, 0.002-0.02% Sr, and 0.0005-0.1% Zr and satisfies the condition of Cu+2.5Mg>=1.25% and in which the contents of Ca, P, and Sb as impurities are controlled to <=0.01%, <=0.002%, and <=0.005%, respectively, and also has a structure in which the mean value of the dendrite arm spacing ofα-Al crystals is regulated to <=50μm and the average length of eutectic Si is regulated to <=10μm. This aluminum alloy casting can contain 0.01-0.25% Ti as the alternative or in addition to Zr or further can contain 0.001-0.001% B, if necessary. This aluminum alloy casting can be produced by melting an aluminum alloy having a regulated composition, subjecting the resultant molten aluminum alloy to gravity die casting, to low pressure die casting, or to die casting, and then performing cooling at >=1 deg.C/sec cooling rate.
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