Aluminum alloy with reduced residual stress, and manufacturing method therefor

Abstract

The present invention relates to an aluminum alloy with reduced residual stress, and provides an aluminum alloy which is an Al—Cu alloy containing a transition metal, and which has, during post-solution-annealing quenching, residual stress lower than that of an Al—Cu alloy containing no transition metals. The alloy of the present invention may inhibit dimensional deformation and damage, which may be caused by residual stress.

1 . An Al—Cu alloy having reduced residual stress, wherein the Al—Cu alloy contains a transition metal,
 wherein the residual stress of the Al—Cu alloy containing the transition metal is lower that residual stress of an Al—Cu alloy free of the transition metal in a rapid cooling process after a solution heat treatment. 
 
     
     
         2 . The Al—Cu alloy having reduced residual stress of  claim 1 , wherein the reduced residual stress of the aluminum alloy is in a range of −90 to −40 MPa. 
     
     
         3 . The Al—Cu alloy having reduced residual stress of  claim 2 , wherein the solution heat treatment process includes a heat treatment performed at 500 to 600° C. for 5 to 7 hours. 
     
     
         4 . The Al—Cu alloy having reduced residual stress of  claim 3 , wherein in the rapid cooling process, the heat-treated alloy is continuously immersed in water at a temperature of 20 to 30° C. 
     
     
         5 . The Al—Cu alloy having reduced residual stress of  claim 3 , wherein the addition of the transition metal includes:
 addition of Cr or Mn alone; or 
 addition of a combination Cr—Zr, a combination Mn—Zr, a combination Cr—Ti, or a combination Cr—V. 
 
     
     
         6 . The Al—Cu alloy having reduced residual stress of  claim 5 , wherein a total content of the transition metal added to the alloy is in a range of 0.1 to 0.5 wt %. 
     
     
         7 . The Al—Cu alloy having reduced residual stress of  claim 1 , wherein the Al—Cu alloy includes a Al-6Cu alloy. 
     
     
         8 . A method for preparing an aluminum alloy having reduced residual stress, the method comprising:
 a first step of melting Al, Cu and an added transition metal;   a second step of leaving a molten metal of the first step to remove gas and impurities from the molten metal; and   a third step of casting the molten metal of the second step to produce a Al—Cu alloy ingot,   wherein the residual stress of the Al—Cu alloy containing the transition metal is lower that residual stress of an Al—Cu alloy free of the transition metal in a rapid cooling process after a solution heat treatment.   
     
     
         9 . The method of  claim 8 , wherein the reduced residual stress of the aluminum alloy is in a range of −90 to −40 MPa. 
     
     
         10 . The method of  claim 9 , wherein the solution heat treatment process includes a heat treatment performed at 500 to 600° C. for 5 to 7 hours. 
     
     
         11 . The method of  claim 10 , wherein in the rapid cooling process, the heat-treated alloy is continuously immersed in water at a temperature of 20 to 30° C. 
     
     
         12 . The method of  claim 10 , wherein the addition of the transition metal includes:
 addition of Cr or Mn alone; or   addition of a combination Cr—Zr, a combination Mn—Zr, a combination Cr—Ti, or a combination Cr—V.   
     
     
         13 . The method of  claim 12 , wherein a total content of the transition metal added to the alloy is in a range of 0.1 to 0.5 wt %. 
     
     
         14 . The method of  claim 8 , wherein the second step includes maintaining the molten metal at 700 to 800° C. for 20 to 40 minutes and maintaining the molten metal in Ar gas for 30 minutes.