Automotive outer panel made from a 6xxx-series aluminium alloy sheet product

Abstract

An automotive outer panel made from a 6xxx-series aluminium alloy sheet product consisting of, in wt. %: Si 0.54% to 0.75%, Mg 0.57% to 0.80%, Cu 0.03% to 0.20%, Mn 0.06% to 0.20%, Fe 0.10% to 0.25%, wherein the ratio of Fe to Mn is in a range of 1.0 to 2.30 (Fe:Mn), Cr up to 0.09%, Zn up to 0.15%, V up to 0.04%, Ti up to 0.15%, other elements and unavoidable impurities each up to 0.05%, total up to 0.2%, balance aluminium.

1 . An automotive outer panel made from a 6xxx-series aluminium alloy sheet product consisting of, in wt. %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Si 
                   0.54% to 0.75%, 
                 
                     
                   Mg 
                   0.57% to 0.80%, 
                 
                     
                   Cu 
                   0.03% to 0.20%, 
                 
                     
                   Mn 
                   0.06% to 0.20%, 
                 
                     
                   Fe 
                   0.10% to 0.25%, 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
               
            
           
         
         wherein the ratio of Fe to Mn is in a range of 1.0 (Fe:Mn) to 2.30 (Fe:Mn), 
       
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Cr 
                   up to 0.09%, 
                 
                     
                   Zn 
                   up to 0.15%, 
                 
                     
                   V 
                   up to 0.04%, 
                 
                     
                   Ti 
                   up to 0.15%, 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
         other elements and unavoidable impurities each up to 0.05%, total up to 0.2%, balance aluminium. 
       
     
     
         2 . The automotive outer panel according the  claim 1 , wherein the aluminium alloy sheet product has the ratio of Fe to Mn less than 2.0. 
     
     
         3 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a ratio of Si to Mg of less than 1.20 (Si:Mg). 
     
     
         4 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a ratio of Si to Mg of at least 0.90 (Si:Mg). 
     
     
         5 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a Mn-content of at least 0.10%. 
     
     
         6 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a Cu-content of not greater than 0.11%. 
     
     
         7 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a Si-content of at least 0.58%. 
     
     
         8 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a Si-content of at most 0.70%. 
     
     
         9 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a Mg-content of at most 0.74%. 
     
     
         10 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has an Fe-content of at least 0.12%. 
     
     
         11 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a gauge in the range of 0.7 to 4.0 mm. 
     
     
         12 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product in T4P temper has a tensile yield strength of 180 MPa or more, a yield point less than 115 MPa when measured within 10 days after solution heat treatment and quench, and an elongation at break of at least 24%, and an uniform elongation of at least 20%, and a strain hardening exponent of at least 0.26. 
     
     
         13 . The automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product in T4P temper has a tensile yield strength of 180 MPa or more, a yield point less than 115 MPa when measured within 10 days after solution heat treatment and quench and less than 130 MPa after 6 months storage at ambient temperature, and an elongation at break of at least 24%, and an uniform elongation of at least 20%, and a strain hardening exponent of at least 0.26. 
     
     
         14 . A method of use of an aluminium alloy sheet product as defined in  claim 1  comprising forming the aluminium alloy sheet product into in an automotive outer panel. 
     
     
         15 . A motor vehicle door comprising an automotive outer panel made from an aluminium sheet product as defined in  claim 1 . 
     
     
         16 . The method of producing an automotive panel, comprising the steps of:
 casting an ingot having a composition according to  claim 1 ;   homogenising the ingot;   hot rolling;   cold rolling into sheet having a final gauge of 0.7 mm to 4.0 mm;   solution heat treating the cold rolled sheet material, followed by quenching;   heating of the solution heat-treated and quenched cold rolled sheet material to a pre-age temperature in a range of 90° C. to 105° C.;   natural ageing and storing.   
     
     
         17 . The method according to  claim 16 , wherein further the aluminium sheet in a forming operation is formed into an automotive body member or panel. 
     
     
         18 . The method according to  claim 16 , wherein the aluminium sheet is heated to a pre-age temperature in a range of 90° C. to 105° C. and coiled at a temperature in said temperature range of 90° C. to 105° C. 
     
     
         19 . The method according to  claim 16 , wherein solution heat treating the cold rolled sheet material is at a temperature in the range of 530° C. to 570° C. 
     
     
         20 . The method according to  claim 16 , wherein homogenisation is at a temperature of 520° C. to 570° C. for 5 hours or more. 
     
     
         21 . The method according to  claim 16 , wherein following the hot rolling, the aluminium is cold rolled to intermediate gauge, intermediate annealed, and cold rolled to a sheet having a final gauge of 0.7 mm to 4.0 mm. 
     
     
         22 . The method according to  claim 21 , wherein the intermediate annealing is by batch annealing at a temperature in a range of 345° C. to 410° C. 
     
     
         23 . An automotive outer panel according the  claim 1 , wherein the aluminium alloy sheet product has the ratio of Fe to Mn less than 1.8 and a ratio of Si to Mg of at most 1.10 (Si:Mg), wherein the aluminium alloy sheet product has a Mn-content of at most 0.18, wherein the aluminium alloy sheet product has a Cu-content of not greater than 0.08%, wherein the aluminium alloy sheet product has a Si-content of at least 0.60%, wherein the aluminium alloy sheet product has a Si-content of at most 0.68%, wherein the aluminium alloy sheet product has a Mg-content of at most 0.70%. 
     
     
         24 . An automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has a Mg-content of at most 0.65%. 
     
     
         25 . An automotive outer panel according to  claim 1 , wherein the aluminium alloy sheet product has an Fe-content of at least 0.15%. 
     
     
         26 . The method according to  claim 16 , wherein further the aluminium sheet in a forming operation is formed into a three-dimensional automotive outer panel. 
     
     
         27 . The method according to  claim 14 , wherein the aluminium alloy sheet product has been formed in the T4P condition. 
     
     
         28 . The method according to  claim 18 , further comprising cooling of the coil to ambient temperature in an ambient environment.