ARTIFICIAL AGING PROCESS FOR ALUMINUM-SILICON (AlSi) ALLOYS FOR DIE CAST COMPONENTS

Abstract

Provided is a method of heat treating a die cast aluminum alloy component. A die cast component has at least one thin walled region with a thickness of ≤5 mm. The alloy has silicon at ≥6.5 mass % to ≤15.5 mass %, copper at ≥0.1 mass % to ≤3.5 mass %, magnesium at ≤0.5 mass %, manganese at ≤0.6 mass %, and chromium at ≤0.6 mass %. The method includes quenching the die cast component at a cooling rate of ≥ about 100° C./second to a first temperature of less than 50° C. and age hardening by heating the die cast component to a second temperature of ≥ about 150° C. for a predetermined duration of time to facilitate formation of particles of Mg 2 Si in an aluminum alloy matrix. The aluminum alloy treated by the method can form lightweight, high strength, high ductility components.

What is claimed is: 
     
         1 . A method of heat treating a die cast aluminum alloy component, the method comprising:
 die casting an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm, the aluminum alloy comprising:
 silicon at greater than or equal to about 6.5% by mass to less than or equal to about 15.5% by mass of the aluminum alloy; 
 copper at greater than or equal to about 0.1% by mass to less than or equal to about 3.5% by mass of the aluminum alloy; 
 chromium at less than or equal to about 0.6% by mass of the aluminum alloy; 
 magnesium at less than or equal to about 0.5% by mass of the aluminum alloy; and 
 manganese at less than or equal to about 0.6% by mass of the aluminum alloy; 
   quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C.; and   age hardening by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg 2 Si) in a matrix of the aluminum alloy.   
     
     
         2 . The method of  claim 1 , wherein the aluminum alloy further comprises:
 iron at less than or equal to about 1.3% by weight;   titanium at less than or equal to about 0.15% by mass of the aluminum alloy;   strontium at less than or equal to about 0.08% by mass of the aluminum alloy;   phosphorus at less than or equal to about 0.003% by weight; and has   a balance of aluminum.   
     
     
         3 . The method of  claim 1 , wherein the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C. 
     
     
         4 . The method of  claim 1 , wherein the die cast component has a yield strength of greater than or equal to about 150 MPa. 
     
     
         5 . The method of  claim 1 , wherein the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa. 
     
     
         6 . The method of  claim 1 , wherein the die cast component has a ductility of greater than or equal to about 5%. 
     
     
         7 . The method of  claim 1 , wherein the particles of magnesium silicide (Mg 2 Si) are substantially homogenously distributed in the matrix of the aluminum alloy of the die cast component. 
     
     
         8 . A method of heat treating a die cast aluminum alloy component, the method comprising:
 die casting an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm, the aluminum alloy comprising:
 silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy; 
 copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy; 
 magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy; 
 manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy; and 
 chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy; and 
 quenching the die cast component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C.; and 
   age hardening by heating the die cast component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg 2 Si) in a matrix of the aluminum alloy.   
     
     
         9 . The method of  claim 8 , wherein the aluminum alloy further comprises:
 iron at less than or equal to about 0.25% by weight;   titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy;   strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy;   phosphorus at less than or equal to about 0.003% by weight; and has   a balance of aluminum.   
     
     
         10 . The method of  claim 8 , wherein the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C. 
     
     
         11 . The method of  claim 8 , wherein the die cast component has a yield strength of greater than or equal to about 150 MPa. 
     
     
         12 . The method of  claim 8 , wherein the die cast component has an ultimate tensile strength of greater than or equal to about 280 MPa. 
     
     
         13 . The method of  claim 8 , wherein the die cast component has a ductility of greater than or equal to about 5%. 
     
     
         14 . The method of  claim 8 , wherein the particles of magnesium silicide (Mg 2 Si) are substantially homogenously distributed in a matrix of the aluminum alloy. 
     
     
         15 . A method of manufacturing a vehicle component, the method comprising:
 die casting the vehicle component with an aluminum alloy to form a die cast component having at least one thin walled region with a thickness of less than or equal to about 5 mm, wherein the aluminum alloy comprises:
 silicon at greater than or equal to about 8.5% by mass to less than or equal to about 10.5% by mass of the aluminum alloy; 
 copper at greater than or equal to about 0.8% by mass to less than or equal to about 1.5% by mass of the aluminum alloy; 
 magnesium at greater than or equal to about 0.1% by mass to less than or equal to about 0.5% by mass of the aluminum alloy; 
 manganese at greater than or equal to about 0.4% by mass to less than or equal to about 0.6% by mass of the aluminum alloy; 
 chromium at greater than or equal to about 0.1% by mass to less than or equal to about 0.6% by mass of the aluminum alloy; 
 titanium at greater than or equal to about 0.05% by mass to less than or equal to about 0.1% by mass of the aluminum alloy; 
 strontium at greater than or equal to about 0.01% by mass to less than or equal to about 0.015% by mass of the aluminum alloy; 
 iron at less than or equal to about 0.25% by weight; 
 phosphorus at less than or equal to about 0.003% by weight; and 
 a balance aluminum; 
   quenching the die cast vehicle component at a cooling rate of greater than or equal to about 100° C./second to a first temperature of less than 50° C.; and   age hardening by heating the die cast vehicle component to a second temperature of greater than or equal to about 150° C. for a predetermined duration of time to facilitate formation of particles of magnesium silicide (Mg 2 Si) in a matrix of the aluminum alloy.   
     
     
         16 . The method of  claim 15 , wherein the vehicle component is selected from the group consisting of: pillars, hinge pillars, panels, door panels, door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets, shock towers, shock tower caps, control arms, suspension components, drive train components, engine mount brackets, transmission mount brackets, alternator brackets, air conditioner compressor brackets, cowl plates, and combinations thereof. 
     
     
         17 . The method of  claim 15 , wherein the second temperature is greater than or equal to about 155° C. to less than or equal to about 220° C. 
     
     
         18 . The method of  claim 15 , wherein the die cast component has a yield strength of greater than or equal to about 150 MPa. 
     
     
         19 . The method of  claim 15 , wherein the die cast component has a ductility of greater than or equal to about 5%. 
     
     
         20 . The method of  claim 15 , wherein the particles of magnesium silicide (Mg 2 Si) are substantially homogenously distributed in a matrix of the aluminum alloy.