Al-Mg-Si-BASED ALUMINUM ALLOY HOLLOW EXTRUDED MATERIAL AND METHOD FOR PRODUCING SAME

摘要

Provided is an Al-Mg-Si-based alloy hollow extruded material which is high strength and which exhibits excellent bending crash resistance and corrosion resistance. This aluminum alloy hollow extruded material contains 0.80-1.25 mass% of Si, 0.65-1.20 mass% of Mg, 0.15-0.30 mass% of Fe, 0.40-0.80 mass% of Mn, 0.01-0.60 mass% of Cu, 0.09-0.21 mass% of Cr and 0.01-0.10 mass% of Ti, with the content of Zr being 0.05 mass% or less and the remainder comprising Al and unavoidable impurities. When the content of Si in the alloy is denoted by α (mass%) and the content of Mg in the alloy is denoted by β (mass%), the relationships 0.90 ≥ α-(β/1.73) ≥ 0.19 and 1.90 ≥ β+(β/1.73) ≥ 1.00 are satisfied. The metal structure in a cross section of the extruded material has a fibrous structure, and the ratio of the area of the fibrous structure relative to the overall area of the cross section is 80% or more. The hollow extruded material has a 0.2% proof stress of 330 MPa or more and the extruded material has a limiting bend radius R of 5 mm or less.