6xxx-series aluminium alloy forging stock material and method of manufacturing thereof

Abstract

A hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material having a thickness in the range of 2 mm to 30 mm, and having a composition including of, in wt. %, Si 0.65-1.4%, Mg 0.60-0.95%, Mn 0.40-0.80%, Cu 0.04-0.28%, Fe up to 0.5%, Cr up to 0.18%, Zr up to 0.20%, Ti up to 0.15%, Zn up to 0.25%, impurities each <0.05%, total <0.2%, balance aluminium, and wherein it has a substantially unrecrystallized microstructure. A method of manufacturing such 6xxx-series hot-rolled aluminium alloy forging stock material. Furthermore, a method of forging a shaped product from the 6xxx-series aluminium alloy forging stock material.

1 . A hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material having a thickness in the range of 2 mm to 30 mm, and having a composition comprising of, in wt. %, 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   Si 
                   0.65%-1.4%, 
                 
                     
                   Mg 
                   0.60%-0.95%, 
                 
                     
                   Mn 
                   0.40%-0.80%, 
                 
                     
                   Cu 
                   0.04%-0.28%, 
                 
                     
                   Fe 
                   up to 0.5%, 
                 
                     
                   Cr 
                   up to 0.18%, 
                 
                     
                   Zr 
                   up to 0.20%, 
                 
                     
                   Ti 
                   up to 0.15%, 
                 
                     
                   Zn 
                   up to 0.25%, 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         impurities each <0.05%, total <0.2%, balance aluminium, 
         and wherein it has a substantially unrecrystallized microstructure. 
       
     
     
         2 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Cu-content is in a range of 0.08% to 0.27%. 
     
     
         3 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Mn-content is in a range of 0.50% to 0.70%. 
     
     
         4 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Si-content is in a range of 0.8% to 1.30%. 
     
     
         5 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Mg-content is in a range of 0.70% to 0.90%. 
     
     
         6 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Cr-content is in the range of 0.06% to 0.18%. 
     
     
         7 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Zr-content is in the range of 0.05% to 0.20%. 
     
     
         8 . A method of manufacturing hot-rolled semi-finished 6xxx-series aluminium alloy forging stock according to  claim 1 , the method comprising the steps of:
 casting of an ingot forming hot-rolling feedstock and having a composition comprising of, in wt. %,   
       
         
           
                 
                 
                 
               
                     
                 
                     
                   Si 
                   0.65%-1.4%, 
                 
                     
                   Mg 
                   0.60%-0.95%, 
                 
                     
                   Mn 
                   0.40%-0.80%, 
                 
                     
                   Cu 
                   0.04%-0.28%, 
                 
                     
                   Fe 
                   up to 0.5%, 
                 
                     
                   Cr 
                   up to 0.18%, 
                 
                     
                   Zr 
                   up to 0.20%, 
                 
                     
                   Ti 
                   up to 0.15%, 
                 
                     
                   Zn 
                   up to 0.25%, 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         impurities each <0.05%, total <0.2%, balance aluminium; 
       
       homogenisation of the cast ingot at a temperature in the range of 460° C. to 570° C.; 
       hot-rolling in one or more rolling passes to a hot-mill exit gauge in the range of 2 to 30 mm, and wherein the hot-mill exit temperature is in the range of 200° C. to 360° C. 
     
     
         9 . The method according to  claim 8 , wherein the hot-mill entry temperature is in a range of 400° C. to 550° C. 
     
     
         10 . A method of manufacturing forged products using hot-rolled semi-finished 6xxx-series aluminium alloy forging stock, comprising the steps of
 solution heat treating of the hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material manufactured according to  claim 8 ;   hot-shaping into a shaped product and having a substantially recrystallized microstructure; and   artificially ageing of the shaped product, preferably to a T6x condition.   
     
     
         11 . The method according to  claim 10 , wherein the shaped product is artificially aged to a T6x-condition. 
     
     
         12 . The method according to  claim 10 , wherein the hot shaping is by means of forging. 
     
     
         13 . The method according to  claim 10 , wherein said shaped product is solution heat treated after the hot-shaping into a shaped product but prior to artificially ageing. 
     
     
         14 . The method according to  claim 10 , wherein the shaped product, after artificially ageing has a bending angle of at least 60° when measured at a 2 mm product in accordance with VDA 238-100. 
     
     
         15 . The method according to  claim 10 , wherein the shaped product, after artificially ageing has a tensile yield strength of at least 330 MPa. 
     
     
         16 . A method of use of a hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material for manufacturing a forged product, the hot-rolled semi-finished 6xxx-series aluminum alloy forging stock material having a thickness in the range of 2 mm to 30 mm, and having a composition comprising of, in wt. %, 
       
         
           
                 
                 
                 
               
                     
                 
                     
                   Si 
                   0.65%-1.4%, 
                 
                     
                   Mg 
                   0.60%-0.95%, 
                 
                     
                   Mn 
                   0.40%-0.80%, 
                 
                     
                   Cu 
                   0.04%-0.28%, 
                 
                     
                   Fe 
                   up to 0.5%, 
                 
                     
                   Cr 
                   up to 0.18%, 
                 
                     
                   Zr 
                   up to 0.20%, 
                 
                     
                   Ti 
                   up to 0.15%, 
                 
                     
                   Zn 
                   up to 0.25%, 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         impurities each <0.05%, total <0.2%, balance aluminium, 
         and wherein the forging stock material has a substantially unrecrystallized microstructure and was obtained by the method according to  claim 8 , the manufacturing of the forged product comprising forging the forging stock material into the forged product having a substantially recrystallized microstructure. 
       
     
     
         17 . The method of use according to  claim 16 , wherein the manufacturing of the forged product comprises the steps of
 solution heat treating of the hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material manufactured according to  claim 8 ;   hot-shaping into a shaped product and having a substantially recrystallized microstructure; and   artificially ageing of the shaped product.   
     
     
         18 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Cu-content is in a range of 0.12% to 0.27%. 
     
     
         19 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Mg-content is in a range of 0.70% to 0.85%. 
     
     
         20 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Cr-content is in the range of 0.06% to 0.14%. 
     
     
         21 . The hot-rolled semi-finished 6xxx-series aluminium alloy forging stock material according to  claim 1 , wherein the Zr-content is in the range of 0.05% to 0.16%. 
     
     
         22 . The method according to  claim 8 , wherein the hot-mill entry temperature is in a range of 435° C. to below 500° C. 
     
     
         23 . The method according to  claim 12 , wherein the forged product, after artificially ageing has a tensile yield strength of at least 330 MPa. 
     
     
         24 . The method according to  claim 16 , wherein the forging comprises die forging.