| 摘要 |
PROBLEM TO BE SOLVED: To provide aluminum alloy die castings by which, without adopting a penetration structure and a steel insert, bolt tightening strength can be secured and reliability of a bolt tightening part can be increased, and also to provide a method for manufacturing such diecast castings. SOLUTION: An aluminum alloy, which has a composition consisting of, by mass ratio, 9.5 to 11.5% Si, 0.15 to 0.50% Mg, 0.2 to 0.80% Mn, 0.1 to 0.2% Ti,≤0.2% Cu,≤0.1% Zn,≤0.2% Fe and the balance Al with inevitable impurities, is used. This aluminum alloy is cast under the conditions of≤50 hPa degree of vacuum and 100 to 350°C metal mold temperature and then subjected to T5 treatment at 433 to 508 K for 100 to 200 min, and hereby hardness Hs of a female screw part and also a dendrite arm spacing DAS are made to 88 to 95 HRF and≤8μm, respectively. COPYRIGHT: (C)2008,JPO&INPIT
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