High-strength hot-forged aluminum alloy

Abstract

In the microstructure of a hot-forged 6000-series aluminum alloy having a specific chemical composition, grains including small grains with a misorientation of 2° or more are refined, and a KAM, which is an average misorientation of the grains, is controlled within a specific range. This allows the hot-forged 6000-series aluminum alloy to have excellent stress corrosion cracking resistance and still have high tensile strength, high yield strength, and high elongation.

1 . A high-strength hot-forged aluminum alloy comprising, in mass percent:
 Si in a content of 0.7% to 1.5%;   Mg in a content of 0.6% to 1.2%;   Fe in a content of 0.01% to 0.5%;   at least one element selected from the group consisting of:
 Mn in a content, of 0.05% to 0.8%, 
 Cr in a content of 0.01% to 0.5%, and 
 Zr in a content of 0.01% to 0.2%; and 
   wherein, in a microstructure in a thickness central part of the hot-forged aluminum alloy as measured by SEM-EBSD analysis,
 grains with a misorientation of 2° or more have an average grain size of 30 μm or less, and 
 grains have a KAM of from 0.6° to 2.0°, where the KAN is an average misorientation of the grains. 
   
     
     
         2 . The high-strength hot-forged aluminum alloy according to  claim 1 , further comprising, in mass percent, at least one element selected from the group consisting of:
 Cu in a content of 0.05% to 1.0%;   Ti in a content of 0.01% to 0.1%; and   Zn in a content of 0.005% to 0.2%.   
     
     
         3 . The high-strength hot-forged aluminum alloy according to  claim 1 , wherein the hot-forged aluminum alloy has a tensile strength of 420 MPa or more, a 0.2% yield strength of 400 MPa or more, and an elongation of 12% or more. 
     
     
         4 . The high-strength hot-forged aluminum alloy according to  claim 2 , wherein the hot-forged aluminum alloy has a tensile strength of 420 MPa or more, a 0.2% yield strength of 400 MPa or more, and an elongation of 12% or more.