| 摘要 |
PROBLEM TO BE SOLVED: To provide a hollow extruded material of Al-Cu-Mg-Si type aluminum alloy useful as a structural body for transport equipment, such as automobile, excellent in strength and corrosion resistance, and capable of manufacture on an actual machine base. SOLUTION: This extruded material has a composition which consists of, by weight, 0.5-1.5% Si, 0.9-1.6% Mg, 1.2-2.5% Cu, further 0.02-0.4% Cr, and the balance Al with inevitable impurities and in which conditional inequalities 3<=Si%+Mg%+Cu%<=4, Mg%<=1.7×Si%, Mg%+Si%<=2.7, 2<=Si%+Cu%<=3.5, and Cu%/2<=Mg%<=(Cu%/2)+0.6 are satisfied and the content of Mn as an impurity is limited to <=0.05%. Moreover, when a tensile test is carried out, in a direction perpendicular to the direction of extrusion, with respect to the deposit of a hollow cross section formed by mean of extrusion in which hot extrusion is performed to form a hollow cross section by using a porthole die or a spider die, breakage occurs in the part other than the deposit and the strength of the deposit is higher than that of the material.
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