Aluminum alloy, method of casting aluminum alloy, and method of producing aluminum alloy product

Abstract

An aluminum alloy is composed of 15% or more and 7.5% or less by mass of silicon, 0.45% or more and 0.8% or less by mass of magnesium, 0.05% or more and 0.35% or less by mass of chromium, and aluminum, assuming that the total amount of the alloy is 100% by mass.

1 . A casting aluminum alloy comprising:
 5.6% or more and 7.5% or less by mass of silicon;   0.45% or more and 0.8% or less by mass of magnesium;   0.05% or more and 0.35% or less by mass of chromium; and aluminum.   
     
     
         2 . The aluminum alloy according to  claim 1 , further comprising unavoidable impurities. 
     
     
         3 . The aluminum alloy according to  claim 2 ,
 wherein the unavoidable impurities comprises iron, and the content of iron in the aluminum alloy is 0.3% or less by mass.   
     
     
         4 . The aluminum alloy according to  claim 1 , further comprising 0.05% or more and 0.3% or less by mass of titanium. 
     
     
         5 . The aluminum alloy according to  claim 1 , the aluminum alloy being free from copper. 
     
     
         6 . The aluminum alloy according to  claim 1 ,
 further comprising: at least one of   0.003% or more and 0.05% or less by mass of strontium;   0.001% or more and 0.03% or less by mass of sodium; and   0.05% or more and 0.15% or less by mass of antimony.   
     
     
         7 . The aluminum alloy according to  claim 1 ,
 wherein when the silicon is crystallized via eutectic reaction, crystallized silicon has an average grain size of 5 μm or smaller.   
     
     
         8 . A casting method of an aluminum alloy, comprising:
 pouring molten alloy comprising 5.6% or more and 7.5% or less by mass of silicon;   0.45% or more and 0.8% or less by mass of magnesium; 0.05% or more and 0.35% or less by mass of chromium; and aluminum; and   allowing the molten alloy to cool and solidify.   
     
     
         9 . The casting method according to  claim 8 , wherein the alloy contains unavoidable impurities. 
     
     
         10 . The casting method according to  claim 9 , wherein the unavoidable impurities comprises iron, and the content of iron in the aluminum alloy is 0.3% or less by mass. 
     
     
         11 . The casting method according to  claim 8 ,
 wherein the alloy further comprises at least one of 0.003% or more and 0.05% or less by mass of strontium; 0.001% or more and 0.03% or less by mass of sodium; and 0.05% or more and 0.15% or less by mass of antimony.   
     
     
         12 . The casting method according to  claim 8 , wherein solidification of the molten alloy is achieved by cooling the molten alloy at a cooling rate of 1° C./sec or faster. 
     
     
         13 . The casting method according to  claim 8 , further comprising performing a solution heat treatment and an aging heat treatment on a solidified aluminum alloy casting. 
     
     
         14 . A method of producing an aluminum alloy product, comprising
 performing cold working and/or hot working on an aluminum alloy casting manufactured by using the casting method according to  claim 8 .   
     
     
         15 . The method of producing an aluminum alloy according to  claim 14 ,
 wherein the cold working and/or hot working are performed on the aluminum alloy casting at a processing rate that provides a cumulative area reduction of 30% or more.