Method of manufacturing a 6000 series aluminum alloy extrusion material high strength with excellent dimensional accuracy

摘要

PROBLEM TO BE SOLVED: To provide an Al alloy extruded material is excellent in strength and excellent in dimensional precision by cooling a billet of Al alloy of the prescribed composition under the prescribed condition after it is extruded. ;SOLUTION: An Al alloy billet having the composition consisting of, by weight, 0.6-1.1% Mg, 0.7-1.2% Si, 0.05-0.8% Cu, 0.1-0.3% Fe, 0.005-0.05% Ti, and 0.0001-0.001% B, 0.3-0.8% in total of one or more kinds of 0.2-0.60% Mn, 0.1-0.4% Cr, and 0.1-0.2% Zr, 0.1-0.7% excessive Si expressed in terms of (Si%-0.58×Mg%) and the balance substantially Al, is extruded so that the temperature immediately after the extrusion is 510-570°C, the extruded material is cooled to 420°C at the cooling speed of ≥30°C/min. to 1000°C/min., cooled at the cooling speed of ≥1000°C/min. in the temperature range of 420-280°C, and cooled at the cooling speed of ≥30°C/min. in the temperature range of 280-150°C.;COPYRIGHT: (C)1998,JPO