Multi-alloy composite sheet for automotive panels

Abstract

Multi-alloy composite sheets and methods of producing the composite sheets for use in automotive applications are disclosed. The automotive application may include an automotive panel having a bi-layer or a tri-layer composite sheet with 3xxx and 6xxx aluminum alloys. The composite sheets may be produced by roll bonding or multi-alloy casting, among other techniques. Each of the composite sheets may demonstrate good flat hem rating and mechanical properties, long shelf life, and high dent resistance, among other properties.

What is claimed is: 
     
         1 . A method comprising:
 (a) hot rolling an ingot to form a sheet;   (b) after step (a), solution heat treating the sheet;   (c) after step (b), cold rolling the sheet; and   (d) after step (c), solution heat treating the sheet.   
     
     
         2 . The method of  claim 1 , wherein step (a) comprises hot rolling the ingot at a temperature of 500 degrees Celsius to 550 degrees Celsius. 
     
     
         3 . The method of  claim 2 , wherein step (a) comprises a ten-fold reduction in a thickness of the ingot. 
     
     
         4 . The method of  claim 1 , wherein step (b) comprises solution heat treating the sheet at a temperature of 540 degrees Celsius to 580 degrees Celsius. 
     
     
         5 . The method of  claim 1 , wherein step (c) comprises cold rolling the sheet at room temperature. 
     
     
         6 . The method of  claim 1 , wherein step (c) comprises cold rolling the sheet sufficiently to result in an 50% to 80% reduction in a thickness of the sheet. 
     
     
         7 . The method of  claim 1 , wherein step (d) comprises solution heat treating at a temperature of 540 degrees Celsius to 580 degrees Celsius. 
     
     
         8 . The method of  claim 1 , wherein step (d) comprises quenching the sheet. 
     
     
         9 . The method of  claim 8 , wherein step (d) comprises pre-aging the sheet after quenching the sheet. 
     
     
         10 . The method of  claim 1 , wherein the ingot of step (a) comprises at least one aluminum alloy. 
     
     
         11 . The method of  claim 10 , wherein the ingot of step(a) comprises a monolithic ingot. 
     
     
         12 . The method of  claim 10 , wherein the ingot of step(a) comprises a composite ingot. 
     
     
         13 . The method of  claim 12 , wherein the composite ingot of step (a) comprises a 6xxx series aluminum alloy and a 3xxx series aluminum alloy. 
     
     
         14 . A method comprising:
 (a) casting an ingot having at least one aluminum alloy;   (b) after step (a), hot rolling the ingot to form a sheet;   (c) after step (b), solution heat treating the sheet;   (d) after step (c), cold rolling the sheet; and   (e) after the step (d), solution heat treating the sheet.   
     
     
         15 . The method of  claim 14 , wherein step (a) comprises multi-alloy casting and/or direct chill casting an ingot having at least one aluminum alloy. 
     
     
         16 . The method of  claim 14 , wherein step (a) comprises casting a monolithic ingot. 
     
     
         17 . The method of  claim 14 , wherein step (a) comprises casting a composite ingot. 
     
     
         18 . The method of  claim 17 , wherein the composite ingot of step (a) comprises a 6xxx series aluminum alloy and a 3xxx series aluminum alloy. 
     
     
         19 . The method of  claim 14 , wherein step (a) comprises homogenizing the ingot after casting the ingot. 
     
     
         20 . The method of  claim 19 , wherein step (a) comprises homogenizing the ingot at a temperature of 540 degrees Celsius to 570 degrees Celsius after casting the ingot. 
     
     
         21 . The method of  claim 20 , wherein step (a) comprises homogenizing the ingot for at least 4 hours after casting the ingot.