| 摘要 |
PROBLEM TO BE SOLVED: To provide a hollow member of an aluminum alloy which is suitable for forming a frame member or a bonding member of an automobile, a vehicle or a building, and is superior in a hydroforming property. SOLUTION: The hollow member of the aluminum alloy comprises a composition of 0.5-1.4% Si, 0.30-0.75% Mg, 0.1-0.4% Fe, 0.005-0.1% Ti, 0.0001-0.004% B, 0.02-0.20% Mn and 0.05-0.25% V so as to satisfy 0.12%<=Mn+V<=0.30%, and 0.03-0.4% Cu, and one or two kinds of 0.02-0.05% Cr and 0.02-0.05% Zr as needed, and Al and inevitable impurities as the balance. It further comprises a crystal grain structure which satisfies a condition of (Dl+Dt)/2<=100μm and Dl/Dt<=2.0, wherein Dl is an average crystal grain size in the longitudinal direction of the hollow member, and Dt is an average crystal grain size in the short transverse direction of the hollow member.
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