Suppression of stress corrosion cracking in high magnesium alloys through the addition of calcium

Abstract

A stress corrosion cracking-resistant aluminum alloy product may include aluminum and a plurality of alloying elements. The plurality of alloying elements may include 3 wt. % to 10 wt. % magnesium and at least one of 0.001 wt. % to 0.1 wt. % calcium. In some embodiments, the plurality of alloying elements may further include 0.001 wt. % to 0.1 wt. % strontium. In some embodiments, the plurality of alloying elements may further include silver.

1 . A stress corrosion cracking-resistant aluminum alloy product, comprising:
 a plurality of alloying elements, including:
 3 wt. % to 10 wt. % magnesium or 6 wt. % to 15 wt. % zinc, magnesium, and copper combined; 
 0.001 wt. % to 0.1 wt. % calcium; and 
   aluminum.   
     
     
         2 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , wherein the plurality of alloying elements further include 0.001 wt. % to 0.1 wt. % strontium. 
     
     
         3 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , wherein the plurality of alloying elements further include 0.001 wt. % to 0.1 wt. % silver. 
     
     
         4 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1  in an H temper. 
     
     
         5 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1  in a T temper. 
     
     
         6 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , comprising a 5xxx series aluminum alloy. 
     
     
         7 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , wherein the plurality of alloying elements does not include zinc. 
     
     
         8 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , comprising a 7xxx series aluminum alloy. 
     
     
         9 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , wherein the plurality of alloying elements comprises 0.1 wt. % to 15 wt. % zinc. 
     
     
         10 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , comprising magnesium-containing precipitates. 
     
     
         11 . The stress corrosion cracking-resistant aluminum alloy product of  claim 10 , comprising magnesium and/or aluminum. 
     
     
         12 . The stress corrosion cracking-resistant aluminum alloy product of  claim 10 , wherein the magnesium-containing precipitates comprise Mg 5 Al 8  beta phase particles, and wherein the stress corrosion cracking-resistant aluminum alloy product comprises less than 0.05 wt. % by weight of the Mg 5 Al 8  beta phase particles. 
     
     
         13 . The stress corrosion cracking-resistant aluminum alloy product of  claim 10 , wherein the magnesium-containing precipitates comprise Mg and/or Zn. 
     
     
         14 . The stress corrosion cracking-resistant aluminum alloy product of  claim 10 , wherein the magnesium-containing precipitates comprise MgZn 2  eta phase particles, and wherein the stress corrosion cracking-resistant aluminum alloy product comprises less than 10 wt. % of the MgZn 2  eta phase particles. 
     
     
         15 . The stress corrosion cracking-resistant aluminum alloy product of  claim 10 , wherein the magnesium-containing precipitates comprise calcium. 
     
     
         16 . The stress corrosion cracking-resistant aluminum alloy product of  claim 10 , wherein a presence of the calcium reduces an amount of the magnesium-containing precipitates in the stress corrosion cracking-resistant aluminum alloy product as referenced to a comparable aluminum alloy product comprising 3 wt. % to 10 wt. % magnesium or 6 wt. % to 12 wt. % zinc, magnesium, and copper combined, and less than 0.001 wt. % calcium and subjected to identical processing conditions. 
     
     
         17 . The stress corrosion cracking-resistant aluminum alloy product of  claim 1 , comprising one or more phases containing calcium, strontium, and/or silver at grain boundaries of the stress corrosion cracking-resistant aluminum alloy product. 
     
     
         18 . The stress corrosion cracking-resistant aluminum alloy product of  claim 17 , wherein the one or more phases comprises calcium metal. 
     
     
         19 . The stress corrosion cracking-resistant aluminum alloy product of  claim 17 , wherein the one or more phases comprises strontium metal. 
     
     
         20 . The stress corrosion cracking-resistant aluminum alloy product of  claim 17 , wherein the one or more phases comprises silver metal. 
     
     
         21 . The stress corrosion cracking-resistant aluminum alloy product of  claim 17 , wherein one phase of the one or more phases comprises a combination of at least two of calcium, magnesium, strontium, silver, or aluminum. 
     
     
         22 . The stress corrosion cracking-resistant aluminum alloy product of  claim 17 , wherein one phase of the one or more phases comprises calcium, strontium, silver, aluminum, and magnesium. 
     
     
         23 . The stress corrosion cracking-resistant aluminum alloy product of  claim 17 , wherein the one or more phases at least partially surround magnesium-containing precipitates located at the grain boundaries. 
     
     
         24 . A method of making a stress corrosion cracking-resistant aluminum alloy product, comprising:
 providing an aluminum alloy in a molten state as a molten aluminum alloy, wherein the aluminum alloy comprises:
 3 wt. % to 10 wt. % magnesium or 6 wt. % to 12 wt. % zinc, magnesium, and copper combined; 
 0.001 wt. % to 0.1 wt. % calcium; and 
 aluminum; and 
   casting the molten aluminum alloy to form an aluminum alloy product.   
     
     
         25 . The method of  claim 24 , further comprising homogenizing the aluminum alloy product to form a homogenized aluminum alloy product. 
     
     
         26 . The method of  claim 24 , further comprising one or more of aging the aluminum alloy product, cold rolling the aluminum alloy product, hot rolling the aluminum alloy product, subjecting the aluminum alloy product to an elevated temperature, or subjecting the aluminum alloy product to a corrosive environment. 
     
     
         27 . The method of  claim 24 , wherein a presence of the calcium in the aluminum alloy product increases an amount of time needed to induce stress corrosion cracks in the aluminum alloy product as referenced to a comparable aluminum alloy product comprising 3 wt. % to 10 wt. % magnesium or 6 wt. % to 12 wt. % zinc, magnesium, and copper combined and less than 0.001 wt. % calcium. 
     
     
         28 . The method of  claim 24 , further comprising subjecting the aluminum alloy to a marine environment. 
     
     
         29 . (canceled) 
     
     
         30 . (canceled)