Forged aluminum alloy material and method for producing same

Abstract

Provided are: a forged aluminum alloy that offers high strength and high toughness and still has excellent corrosion resistance even when having a smaller thickness; and a method for producing the forged aluminum alloy. The forged aluminum alloy contains Mg in a content of 0.70 to 1.50 mass percent, Si in a content of 0.80 to 1.30 mass percent, Cu in a content of 0.30 to 0.90 mass percent, Fe in a content of 0.10 to 0.40 mass percent, Ti in a content of 0.005 to 0.15 mass percent, and at least one element selected from the group consisting of Mn in a content of 0.10 to 0.60 mass percent, Cr in a content of 0.10 to 0.45 mass percent, and Zr in a content of 0.05 to 0.30 mass percent, with the remainder consisting of Al and inevitable impurities. The forged aluminum alloy has a major axis of Q phase of 50 to 500 nm in a maximum-stress-receiving region.

1 . A forged aluminum alloy comprising:
 Mg in a content of 0.70 to 1.50 mass percent;   Si in a content of 0.80 to 1.30 mass percent;   Cu in a content of 0.30 to 0.90 mass percent;   Fe in a content of 0.10 to 0.40 mass percent;   Ti in a content of 0.005 to 0.15 mass percent; and   at least one element selected from the group consisting of:
 Mn in a content of 0.10 to 0.60 mass percent; 
 Cr in a content of 0.10 to 0.45 mass percent; and 
 Zr in a content of 0.05 to 0.30 mass percent, 
   with the remainder consisting of Al and inevitable impurities,   the forged aluminum alloy having a major axis of Q phase of 50 to 500 nm in a maximum-stress-receiving region.   
     
     
         2 . The forged aluminum alloy according to  claim 1 ,
 wherein the forged aluminum alloy has an average grain size of 50.0 μm or less in terms of minor axis in the maximum-stress-receiving region, and   wherein the forged aluminum alloy has an area percentage of recrystallized grains of 30.0% or less in a transverse section including the maximum-stress-receiving region.   
     
     
         3 . The forged aluminum alloy according to  claim 1 , wherein the forged aluminum alloy has undergone a surface treatment. 
     
     
         4 . The forged aluminum alloy according to  claim 1 , wherein the forged aluminum alloy has undergone shot blasting. 
     
     
         5 . A method for producing a forged aluminum alloy,
 the forged aluminum alloy comprising:   Mg in a content of 0.70 to 1.50 mass percent;   Si in a content of 0.80 to 1.30 mass percent;   Cu in a content of 0.30 to 0.90 mass percent;   Fe in a content of 0.10 to 0.40 mass percent;   Ti in a content of 0.005 to 0.15 mass percent; and   at least one element selected from the group consisting of:
 Mn in a content of 0.10 to 0.60 mass percent; 
 Cr in a content of 0.10 to 0.45 mass percent; and 
 Zr in a content of 0.05 to 0.30 mass percent 
   with the remainder consisting of Al and inevitable impurities,   the method comprising the steps of:   a) melting an aluminum alloy having the chemical composition to give a molten metal;   b) casting the molten metal to give an ingot;   c) subjecting the ingot to homogenization;   d) heating the ingot after homogenization as a forging material and forging the heated forging material via hot forging; and   e) tempering the material after the step d), the tempering step comprising in the sequence set forth:
 solution heat treatment; 
 quenching at 20° C. to 70° C. for 30 minutes or shorter; 
 drying for one hour or shorter; and 
 over-aging at 180° C. to 220° C. for 2 to 24 hours.