Patent ID: 8105449
Filing Date: 2012-01-31
Classification: C22C,C22F

Abstract:
1. A method of manufacturing an aluminum alloy extruded product comprising: casting a billet using an aluminum alloy including 6.40 to 7.2 mass % of Zn, 1.0 to 1.6 mass % of Mg, 0.1 to 0.4 mass % of Cu, 0.01 to 0.03 mass % of Mn, 0.01 to 0.02 mass % of Cr, 0.18 to 0.20 mass % of Zr, 0.20 to 0.25 mass % of a total amount of Mn, Cr and Zr, 0.20 mass % or less of Fe, and 0.10 mass % or less of Si, excess Mg content with respect to stoichiometric composition of MgZn homogenizing the cast billet at 520° C. to 540° C.; extruding the homogenized product; press edge quenching the extruded product at an air cooling rate of 29 to 80° C./min; natural aging the extruded product at room temperature; and artificial aging the extruded product, an increase in proof stress of the extruded product subjected to the artificial aging after a time period of within 24 hours of the natural aging being 5 MPa or less with respect to the proof stress of the extruded product subjected to the artificial aging after 200 hours of the natural aging, and an extension of the extruded product being more than 16.1 to 18.3%.