Process for low-cost tempering of aluminum casting

Abstract

A thermally stable component formed of a tempered aluminum alloy casting which reduced costs is provided. The aluminum alloy typically has an elongation of at least 8% after casting, which is preferred for self-piercing rivet processes. The aluminum alloy leaves a casting facility in the as-cast (F temper) condition. The cast aluminum alloy is then shipped to another entity, such as an OEM, and is subjected to an artificial aging process, such as on theOEM's existing paint line, rather than at the casting facility. The artificial aging process typically includes electrodeposition coating and curing. The components that can be formed by the reduced cost method include lightweight automotive vehicle components, including structural, body-in-white, suspension, or chassis components, such as front shock towers, front body hinge pillars, tunnels, and rear rails.

What is claimed is: 
     
         1 . A method of manufacturing a cast aluminum alloy, comprising the steps of:
 casting an aluminum alloy;   applying a coating to the cast aluminum alloy;   heating the coated cast aluminum alloy;   the cast aluminum alloy having an F temper designation before the heating step;   the cast aluminum alloy having a yield strength (YS) ranging from 90 to 200 MPa, an ultimate tensile strength (UTS) ranging from 220 to 300 MPa, and an elongation percentage (%) of 7.0% to 19% before the heating step when tested according to an ASTM E8 specification; and   the heating step including curing the coating on the cast aluminum alloy.   
     
     
         2 . A method according to  claim 1  including transferring the aluminum alloy from a first location to a second location after casting the aluminum alloy, and wherein the heating of the cast aluminum alloy is conducted at the second location. 
     
     
         3 . A method according to  claim 2 , wherein the second location where the heating step is conducted is an original equipment manufacturer (OEM) of a component for a vehicle and the first location is a foundry;
 the heating step is conducted in a paint bake oven, electrodeposition coating oven, a primer oven, and/or an enamel oven;   the aluminum alloy forms at least a portion of a component for an automotive vehicle;   the heating step is conducted at temperatures ranging from 180° F. to 385° F.;   the heating step includes at least one cycle, wherein each cycle ranges from 9 to 25 minutes; and   piercing the cast aluminum alloy without forming a hole in the aluminum alloy prior to the piercing step.   
     
     
         4 . A method according to  claim 2 , wherein the second location where the heating step is conducted is an original equipment manufacturer (OEM) of a component for a vehicle. 
     
     
         5 . A method according to  claim 2 , wherein the first location is a foundry. 
     
     
         6 . A method according to  claim 1 , wherein the heating step is conducted in a paint bake oven, an electrodeposition coating oven, a primer oven, and/or an enamel oven. 
     
     
         7 . A method according to  claim 1 , wherein the heating step is conducted at temperatures ranging from 180° F. to 385° F. 
     
     
         8 . A method according to  claim 1 , wherein the heating step includes at least one cycle, wherein each cycle ranges from 9 to 25 minutes. 
     
     
         9 . A method according to  claim 1 , wherein the aluminum alloy forms at least a portion of a component for an automotive vehicle. 
     
     
         10 . A method according to  claim 9 , wherein the component is a front shock tower, front body hinge pillar, tunnel, rear rail, door inner panel, door mirror bracket, cross car beam, inner torque box, outer torque box, or rear shock mount. 
     
     
         11 . A method according to  claim 1  including piercing the cast aluminum alloy without forming a hole in the aluminum alloy prior to the piercing step. 
     
     
         12 . A method according to  claim 11 , wherein the piercing step is conducted prior to the heating of the cast aluminum alloy. 
     
     
         13 . A method according to  claim 11 , wherein the piercing step is conducted prior to the coating step and prior to the heating of the cast aluminum alloy. 
     
     
         14 . A method according to  claim 1 , wherein the coating includes an epoxy. 
     
     
         15 . A method according to  claim 1 , wherein the coating is applied by electrodeposition. 
     
     
         16 . A method according to  claim 1  including melting the aluminum alloy prior to the casting step;
 trimming, piercing, deburring, grinding, cutting, and/or machining the aluminum alloy after the casting step; and 
 wherein the heating step includes curing the coating on the cast aluminum alloy after the trimming, piercing, deburring, grinding, cutting, and/or machining step. 
 
     
     
         17 . A method according to  claim 1 , wherein the aluminum alloy includes copper, iron, silicon in an amount of 4.0 to 9.0 weight percent (wt. %), manganese in an amount up to 0.60 wt. %, magnesium in an amount of 0.10 to 0.60 wt. %, titanium in an amount up to 0.15 wt. %, and strontium in an amount of 0.01 to 0.6 wt. %, based on the total weight of the aluminum alloy. 
     
     
         18 . A method according to  claim 1 , wherein the cast aluminum alloy has an elongation of at least 8% prior to the heating of the cast aluminum alloy. 
     
     
         19 . A method according to  claim 1 , wherein the cast aluminum alloy has a T85 temper designation after the heating step. 
     
     
         20 . A method according to  claim 1 , wherein the cast aluminum alloy has a yield strength (YS) ranging from 100 to 220 MPa, an ultimate tensile strength (UTS) ranging from 230 to 320; and an elongation percentage (%) of 6.0% to 15% after the heating of the cast aluminum alloy.