6xxxx-series rolled sheet product with improved formability

Abstract

A rolled 6xxx-series aluminium alloy sheet product including, in wt. %: Mg 0.10-1.3%, Si 0.25-1.4%, Cu up to 0.45%, Mn up to 0.50%, Fe 0.10-0.45%, Sr 0.01-0.05%, and wherein the ratio Fe/Sr is in a range of 4 to 40, Ti up to 0.20%, Cr up to 0.30%, Zr up to 0.20%, V up to 0.20%, Zn up to 0.35%, Sn up to 0.075%, impurities and balance aluminium. A method of manufacturing the 6xxx-series aluminium alloy sheet product.

1 . A rolled 6xxx-series aluminium alloy sheet product consisting of an aluminum alloy consisting of, in wt. %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Mg 
                   0.10% to 1.3%, 
                 
                     
                   Si 
                   0.25% to 1.4%, 
                 
                     
                   Cu 
                   up to 0.45%, 
                 
                     
                   Mn 
                   up to 0.50%, 
                 
                     
                   Fe 
                   0.10% to 0.45%, 
                 
                     
                   Sr 
                   0.01% to 0.05%, 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
               
            
           
         
         and wherein the ratio Fe/Sr is in a range of 4 to 40, 
       
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Ti 
                   up to 0.20%, 
                 
                     
                   Cr 
                   up to 0.30%, 
                 
                     
                   Zr 
                   up to 0.20%, 
                 
                     
                   V 
                   up to 0.20%, 
                 
                     
                   Zn 
                   up to 0.35%, 
                 
                     
                   Sn 
                   up to 0.075%, 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
               
            
           
         
         other elements and impurities each <0.05%, total <0.15%, balance aluminium. 
       
     
     
         2 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Si-content is at least 0.50%. 
     
     
         3 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Mg-content is less than 1.3%. 
     
     
         4 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the ratio Si/Mg is at least 0.90. 
     
     
         5 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the ratio Si/Mg is in a range of 0.90 to 1.40. 
     
     
         6 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the ratio of Si/Mg is in a range of 2.0 to 7.0. 
     
     
         7 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe/Sr ratio is in a range of 4 to 40. 
     
     
         8 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Mn-content is in a range of 0.02% to 0.50%. 
     
     
         9 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Cr-content is in a range of 0.01% to 0.30%. 
     
     
         10 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Cu-content is at least 0.02%. 
     
     
         11 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Cu-content at most 0.40%. 
     
     
         12 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe-content at least 0.18%. 
     
     
         13 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the aluminium alloy sheet product has a gauge in the range of 0.7 mm to 4.0 mm. 
     
     
         14 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein said sheet product is provided in the form of a shaped three-dimensional automotive body member. 
     
     
         15 . A method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the method comprises the steps of:
 (a) semi-continuously or continuously casting an ingot of the aluminium alloy;   (b) homogenising of the ingot;   (c) rolling of the ingot into an aluminium alloy rolled sheet product having a final gauge in a range of 0.7 mm to 4.0 mm;   (d) solution heat treating the aluminium alloy sheet product at a temperature of at least 500° C.;   (e) after the solution heat treating, quenching of the aluminium alloy sheet product; and   (f) natural ageing of the quenched aluminium alloy sheet product.   
     
     
         16 . The method according to  claim 15 , further comprising artificially ageing of the solution heat treated and quenched rolled sheet product. 
     
     
         17 . A method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , the method comprising:
 continuously casting an ingot of the aluminium alloy;   homogenising of the ingot;   rolling the aluminium alloy into an aluminium alloy rolled sheet product having a final gauge in the range of 0.7 to 4.0 mm;   solution heat treating the aluminium alloy sheet product at a temperature of at least 500° C.;   after the solution heat treating, quenching of the aluminium alloy sheet product; and   natural ageing of the quenched aluminium alloy sheet product.   
     
     
         18 . The method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 15 , wherein solution heat treating the aluminium alloy sheet product is at a temperature in a range of 520° C. to 570° C. 
     
     
         19 . The method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 15 , wherein the solution heat treated and quenched aluminium alloy sheet product has been pre-aged. 
     
     
         20 . The method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 15 , wherein the natural ageing of the quenched aluminium alloy sheet product is for at least 72 hours. 
     
     
         21 . The method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 15 , wherein the method further comprising the step of shaping of the 6xxx-series aluminium alloy sheet product into a three-dimensional form. 
     
     
         22 . The method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 21 , wherein the 6xxx-series aluminium alloy sheet product in a three-dimensional form is subjected to a paint-bake cycle. 
     
     
         23 . A method of use of a rolled 6xxx-series aluminium alloy sheet product according to  claim 1  comprising forming the sheet into a shaped three-dimensional automotive body member. 
     
     
         24 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Si-content is at least 0.65%. 
     
     
         25 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Mg-content is less than 1.0%. 
     
     
         26 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the ratio of Si/Mg is in a range of 2.5 to 7.0. 
     
     
         27 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe/Sr ratio is in a range of 5 to 40. 
     
     
         28 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe/Sr ratio is in a range of 6 to 40. 
     
     
         29 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe/Sr ratio is in a range of 6 to 20. 
     
     
         30 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Mn-content is in a range of 0.02% to 0.20%. 
     
     
         31 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Cr-content is in a range of 0.01% to 0.20%. 
     
     
         32 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Cu-content is at least 0.04%. 
     
     
         33 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Cu-content at most 0.20%. 
     
     
         34 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe-content at least 0.20%. 
     
     
         35 . The rolled 6xxx-series aluminium alloy sheet product according to  claim 1 , wherein the Fe-content at least 0.22%. 
     
     
         36 . The method of manufacturing a rolled 6xxx-series aluminium alloy sheet product according to  claim 15 , wherein the solution heat treated and quenched aluminium alloy sheet product has been pre-aged at a temperature in a range of 50° C. to 130° C.