Al-Mg-Si based aluminum alloy extrusion

Abstract

An Al-Mg-Si based aluminum alloy extrusion having large strength, absorbable impact energy and resistance against compressing cracking, wherein the average size of Mg 2 Si precipitation in the [1 0 0] and [0 1 0] directions of the (1 0 0) plane inside grains is 20 nm or more, the distribution density of the Mg 2 Si precipitation in the [0 0 1] direction of the (1 0 0 ) plane is 100 or more per μm 2 , and the size of precipitations on grain boundaries is 1000 nm or less. Alternatively, in the Al-Mg-Si based aluminum alloy extrusion, a tensile strength obtained from a tensile test performed at a strain rate of 1000 per second is from 150 to 400 N/mm 2 (both inclusive).

What is claimed is:  
     
         1 . An Al-Mg-Si based aluminum alloy extrusion, wherein the average size of Mg 2 Si precipitation in the [1 0 0] and [0 1 0] directions of the (1 0 0) plane inside grains is 20 nm or more, the distribution density of the Mg 2 Si precipitation in the [0 0 1] direction of the (1 0 0) plane is 100 or more per μm 2 , and the size of precipitations on grain boundaries is 1000 nm or less.  
     
     
         2 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 1 , which comprises an Al-Mg-Si based aluminum alloy comprising Mg: 0.2-1.6% (“%” represents “% by weight” in all claims) and Si: 0.2-1.8%.  
     
     
         3 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 2 , which comprises an Al-Mg-Si based aluminum alloy comprising Cu: 1.0% or less.  
     
     
         4 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 3 , which comprises an Al-Mg-Si based aluminum alloy comprising Mn: 0.05-0.5% or less.  
     
     
         5 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 4 , which comprises an Al-Mg-Si based aluminum alloy comprising one or more selected from the following: 
 Ti: 0.01-0.1% or less, Cr: 0.01-0.2% and Zr: 0.01-0.2%.    
     
     
         6 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 1 , wherein the texture of the crystal is a fiber texture.  
     
     
         7 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 1 , which has a tensile strength of 200 N/mm 2  or more, and a proof stress of 150 N/mm 2  or more.  
     
     
         8 . An Al-Mg-Si based aluminum alloy extrusion excellent in impact energy absorption property, wherein a tensile strength obtained from a tensile test performed at a strain rate of 1000 per second is from 150 to 400 N/mm 2  (both inclusive).  
     
     
         9 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 8 , which comprises an Al-Mg-Si based aluminum alloy comprising Mg: 0.2-1.6% and Si: 2-1.8%.  
     
     
         10 . The Al-Mg-Si based aluminum alloy extrusion according to  claim 9 , which comprises Mg: 0.35-1.1%, Si: 0.5-1.3%, Cu: 0.15-0.7%, Ti: 0.005-0.2% and Zr: 0.01-0.2%, and further comprises one or two selected from the following: Mn: 0.05-0.5% and Cr: 0.05-0.15%, the balance being Al and impurities.  
     
     
         11 . A fabric for a car, which comprises an extrusion of the Al-Mg-Si based aluminum alloy extrusion according to any one of claims  1 - 10 .