| 摘要 |
<p>The present invention provides a high-strength aluminum alloy extruded product exhibiting excellent corrosion resistance and secondary workability and suitably used as a structural material for transportation equipment such as automobiles, railroad vehicles, and aircrafts, and a method of manufacturing the same. The aluminum alloy extruded product has a composition containing 0.6 to 1.2% of Si, 0.8 to 1.3% of Mg, and 1.3 to 2.1% of Cu while satisfying the following conditional expressions (1), (2), (3), and (4), 3 % ‰¤ Si % + Mg % + Cu % ‰¤ 4 % Mg % ‰¤ 1.7 × Si % Mg % + Si % ‰¤ 2.7 % Cu % / 2 ‰¤ Mg % ‰¤ ( Cu % / 2 ) + 0.6 % and further containing 0.04 to 0.35% of Cr, and 0.05 % or less of Mn as an impurity, with the balance being aluminum and unavoidable impurities. The cross section of the extruded product has a recrystallized structure with an average grain size of 500 µm or less. The manufacturing method includes, when extruding the aluminum alloy into a solid product by using a solid die, extruding the aluminum alloy by using a solid die in which a bearing length (L) is 0.5 mm or more and the bearing length (L) and the thickness (T) of the solid product have a relationship expressed as "L‰¤5T", and, when extruding the aluminum alloy into a hollow product by using a porthole die or a bridge die, extruding the aluminum alloy while setting the ratio of the flow speed of the aluminum alloy in a joining section to the flow speed of the aluminum alloy in a non-joining section in a chamber, where the billet reunites after entering a port section of the die in divided flows and subsequently encircling a mandrel, at 1.5 or less.</p> |
