Patent ID: 8168013
Filing Date: 2012-05-01
Classification: C22C

Abstract:
1. A method of producing an aluminum alloy extruded product comprising: preparing a molten aluminum alloy consisting of 0.3 to 0.8 mass % of Mg, 0.5 to 1.2 mass % of Si, 0.3 mass % or more of excess Si with respect to the Mg casting the molten aluminum alloy into a billet at a casting speed of extruding the billet into an aluminum alloy extruded product; water cooling the aluminum alloy extruded product immediately after the extrusion at a cooling rate of 500° C./min or more; and artificial aging the aluminum alloy extruded product, thereby producing the aluminum alloy extruded product having a fatigue strength of 140 MPa or more, a fatigue ratio of 0.45 or more, an interval between striations on a fatigue fracture surface of 5.0 μm or less and a maximum length of Al—Fe—Si crystallized products of 10 μm or less.