Aluminum alloy material and production method therefor

Abstract

An aluminum alloy material as one aspect of the present disclosure has a chemical composition including: Zn: more than 6.5% (mass %, same applies hereafter) and 8.5% or less; Mg: 0.5% or more and 1.5% or less; Cu: 0.10% or less; Fe: 0.30% or less; Si: 0.30% or less; Mn: less than 0.05%; Cr: less than 0.05%; Zr: 0.05% or more and 0.10% or less; and Ti: 0.001% or more and 0.05% or less, a balance including Al and inevitable impurities. In the aluminum alloy material, a mass ratio of Zn to Mg (Zn/Mg) is 5 or more and 16 or less, and a metallographic structure includes an equigranular recrystallized structure.

1 . An aluminum alloy material having a chemical composition comprising:
 Zn: more than 6.5% (mass %, same applies hereafter) and 8.5% or less;   Mg: 0.5% or more and 1.5% or less;   Cu: 0.10% or less;   Fe: 0.30% or less;   Si: 0.30% or less;   Mn: less than 0.05%;   Cr: less than 0.05%;   Zr: 0.05% or more and 0.10% or less; and   Ti: 0.001% or more and 0.05% or less,   a balance comprising Al and inevitable impurities,   wherein a mass ratio of Zn to Mg (Zn/Mg) is 5 or more and 16 or less, and   wherein a metallographic structure comprises a recrystallized structure, which is equigranular.   
     
     
         2 . The aluminum alloy material according to  claim 1 ,
 wherein the recrystallized structure comprises crystal grains having an average grain diameter of 500 μm or less in a cross-section parallel to a direction orthogonal to a working direction, and a difference between a maximum value and a minimum value of grain diameters of the crystal grains is less than 300 μm.   
     
     
         3 . A production method for an aluminum alloy material, a metallographic structure of which comprises an equigranular recrystallized structure, the method comprising:
 preparing an ingot having a chemical composition comprising:
 Zn: more than 6.5% (mass %, same applies hereafter) and 8.5% or less; 
 Mg: 0.5% or more and 1.5% or less; 
 Cu: 0.10% or less; 
 Fe: 0.30% or less; 
 Si: 0.30% or less; 
 Mn: less than 0.05%; 
 Cr: less than 0.05%; 
 Zr: 0.05% or more and 0.10% or less; and 
 Ti: 0.001% or more and 0.05% or less, 
 a balance comprising Al and inevitable impurities, 
 wherein a mass ratio of Zn to Mg (Zn/Mg) is 5 or more and 16 or less; and 
   performing a homogenizing treatment in which the ingot is heated at a temperature higher than 540° C. and 580° C. or lower for 1 hour or longer and 24 hours or shorter.