High-strength aluminum alloy extruded material and method for manufacturing the same

Abstract

A high-strength aluminum alloy extruded material contains Si: 0.70 to 1.3 mass %; Mg: 0.45 to 1.2 mass %; Cu: 0.15 to less than 0.40 mass %; Mn: 0.10 to 0.40 mass %; Cr: more than 0 to 0.06 mass %; Zr: 0.05 to 0.20 mass %; Ti: 0.005 to 0.15 mass %, Fe: 0.30 mass % or less; V: 0.01 mass % or less; the balance being Al and unavoidable impurities Crystallized products in the alloy have a particle diameter of a is 5 μm or less. Furthermore, an area ratio of a fibrous structure in a cross section parallel to an extruding direction during hot extrusion is 95% or more.

What is claimed is: 
     
         1 . A high-strength aluminum alloy extruded material comprising:
 Si: 0.70 to 1.3 mass %;   Mg: 0.45 to 1.2 mass %;   Cu: 0.15 to less than 0.40 mass %;   Mn: 0.10 to 0.40 mass %;   Cr: more than 0 to 0.06 mass %;   Zr: 0.05 to 0.20 mass %;   Ti: 0.005 to 0.15 mass %,   Fe: 0.30 mass % or less;   V: 0.01 mass % or less; and   the balance being Al and unavoidable impurities,   wherein crystallized products in the alloy have a particle diameter of 5 μm or less, and   wherein an area ratio of a fibrous structure in a cross section parallel to an extruding direction during hot extrusion is 95% or more.   
     
     
         2 . A structural member for vehicle comprising the high-strength aluminum alloy extruded material according to  claim 1 . 
     
     
         3 . A method for manufacturing a high-strength aluminum alloy extruded material, comprising:
 producing an ingot which comprises:   Si: 0.70 to 1.3 mass %;   Mg: 0.45 to 1.2 mass %;   Cu: 0.15 to less than 0.40 mass %;   Mn: 0.10 to 0.40 mass %;   Cr: more than 0 to 0.06 mass %;   Zr: 0.05 to 0.20 mass %;   Ti: 0.005 to 0.15 mass %,   Fe: 0.30 mass % or less;   V: 0.01 mass % or less; and   the balance being Al and unavoidable impurities;   subjecting the ingot to a homogenization treatment that includes holding the ingot at a temperature of not lower than 450° C. and lower than 500° C. for 2 to 30 hours;   subjecting the homogenized ingot to hot extrusion in a state where the temperature of the ingot at the start of the hot extrusion is held at 480° C. to 540° C. so as to form an extruded material;   quenching the extruded material to 150° C. or lower at a cooling rate of 2° C./sec. to 100° C./sec. while the temperature of the extruded material is held at 480° C. or higher; and   thereafter, subjecting the extruded material to an aging treatment that includes heating the extruded material at a temperature of 150° C. to 200° C. for 1 to 24 hours.