Process of producing 5xxx series aluminum alloys with high mechanical, properties through twin-roll casting

Abstract

Present invention concerns a method for making fine-grained, formable aluminium alloy strips containing (by weight) essentially between 0.5-6.5% Mg, 0-0.50% Si, 0-0.60% Fe, 0-1.2% Mn, 0-0.50% Cr, by twin-roll casting to a thickness ranging between 4 and 6.5 mm and cold rolling the strips to an intermediate gauge and reroll annealing the intermediate gauge material. The reroll-annealed material is then cold rolled to a final sheet gauge followed by a final recrystallizing or back annealing. The combination of controlled casting parameters, controlled amounts of Fe, Si, Mn, Cr and Mg and reroll and final annealing temperatures results in an improved sheet product in terms of finer grain size, higher elongation and formability, age softening and better corrosion resistance. Homogenization may be performed at 420 ° C. to 550 ° C. for a period of 4 to 15 hours and recrystallization is performed at 280° C. to 375° C. for a period of not less than 4 hours and not more than 8 hours.

1 - 10 . cancelled.  
     
     
         11 . A process capable for producing 5XXX series aluminum alloys through twin-roll casting comprising the steps of: 
 (a) providing the twin-roll caster with a melt composition comprising between 0.5-6.5% Mg, 0-0.50% Si, 0-0.60% Fe, 0-1.2% Mn and 0-0.50% Cr by weight, where the temperature of the melt is kept essentially between 690° C. and 715° C.,    (b) operating the twin-roll caster continuously under critical conditions in which the casting speed is varied between 0.8 m/min and 1.5 m/min,    (c) maintaining a set-back distance essentially between 48 mm and 65 mm, where set-back is the critical distance between the center lines of caster rolls and exit side of the molten metal from the caster tip,    (d) casting a strip with uniform thickness adjusted within the range of 3-7 mm.,    (e) applying a first cold rolling treatment to as-cast strip,    (f) allowing recrystallization at the critical gauge essentially in the range of 280° C. to about 375° C., for a period of not less than 4 hours and not more than 8 hours, and    (g) applying a second cold rolling treatment to said strip following the recrystallization step.    
     
     
         12 . A process according to  claim 11 , wherein the process further comprises an homogenization step applied to said as-cast strip, prior to applying the first cold rolling treatment of step e), at a temperature ranging between 420° C. to 550° C. for a period of 4 to 15 hours,  
     
     
         13 . A process according to  claim 12 , wherein the process further comprises the step of applying a cold rolling treatment to as-cast strip prior to applying said homogenization treatment.  
     
     
         14 . A process as set forth in any of the  claims 11  to  13 , further comprising a final annealing treatment suitable for producing H2X tempers, wherein said final annealing treatment is applied essentially within temperature range of 130°-250° C., for a period of not less than 100 minutes and not more than 8 hours.  
     
     
         15 . A process as set forth in any of the  claims 11  to  13 , further comprising a final annealing treatment suitable for producing H3X tempers, wherein said final annealing treatment is applied essentially within the temperature range of 100°-190° C. for a period of about 2 hours to 6 hours.  
     
     
         16 . A process capable for producing 0 tempers of 5XXX series aluminum alloys through twin-roll casting comprising the steps of: 
 (a) providing the twin-roll caster with a melt composition comprising between 0.5-6.5 % Mg, 0-0.50% Si, 0-0.60% Fe, 0-1.2% Mn and 0-0.50% Cr by weight, where the temperature of the melt is kept essentially between 690° C. and 715° C.,    (b) operating the twin-roll caster continuously under critical conditions in which the casting speed is varied between 0.8 m/min and 1.5 m/min,    (c) maintaining a set-back distance essentially between 48 mm and 65 mm, where set-back is the critical distance between the center lines of caster rolls and exit side of the molten metal from the caster tip,    (d) casting a strip with uniform thickness adjusted within the range of 3-7 mm.,    (e) applying a cold rolling treatment to as-cast strip and allowing recrystallization at the final gauge essentially in the range of 280° C. to about 375° C., for a period of not less than 4 hours and not more than 8 hours.    
     
     
         17 . A process as set forth in  claim 16  suitable for producing 0 tempers, wherein the process further comprises the step of applying a homogenization treatment to as-cast strip, prior to applying said the cold rolling treatment of step (e), at a temperature ranging between 420° C. to 550° C. for a period of 4 to 15 hours.  
     
     
         18 . A process as set forth in  claim 17  suitable for producing 0 tempers, wherein the process further comprises the step of applying a first cold rolling treatment to as-cast strip before applying said homogenization treatment.