Compact aluminium alloy heat treatment method

Abstract

The invention relates to a method for the heat treatment of a moving aluminium alloy strip, the aluminium strip has an upper-surface and a lower-surface, the method comprising moving the aluminium strip over at least two rotating heating rolls, wherein the heating rolls comprises an outer-surface, such that a surface of the aluminium strip is in heat-transfer contact with the outer-surface of the heating rolls to induce heat into the aluminium strip to heat the aluminium strip at an annealing temperature, and comprising moving the aluminium alloy strip over a first rotating heating roll followed by moving the aluminium strip over a second rotating heating roll such that alternating the upper-surface and the lower-surface of the aluminium strip are in heat-transfer contact with the outer-surface of the rotating heating rolls.

1 . Method for the heat treatment of a moving aluminium alloy strip, the aluminium strip has an upper-surface and a lower-surface, the method comprising moving the aluminium strip over at least two rotating heating rolls, wherein the heating rolls comprise an outer-surface, such that a surface of the aluminium strip is in heat-transfer contact with a part of the outer-surface of the heating rolls to induce heat into the aluminium alloy strip to heat the aluminium alloy strip at an annealing temperature, and comprising moving the aluminium alloy strip over a first rotating heating roll followed by moving the aluminium strip over a second rotating heating roll such that alternating the upper-surface and the lower-surface of the aluminium strip are in heat-transfer contact with the outer-surface of the rotating heating rolls. 
     
     
         2 . The method according to  claim 1 , wherein the outer-surface of the heating rolls is coated with a composite diamond coating. 
     
     
         3 . The method according to  claim 1 , wherein the outer-surface of the heating rolls is coated with a ceramic coating, preferably selected from the group consisting of titanium nitride, tungsten carbide, and chromium nitride. 
     
     
         4 . The method according to  claim 1 , wherein the aluminium alloy strip is moving while one surface is in heat-transfer contact with a rotating heating roll and heat-loss of the other surface of the aluminium alloy strip is modulated by the presence of a screen. 
     
     
         5 . The method according to  claim 1 , wherein the aluminium alloy strip following the heat treatment is quenched to below 100° C. 
     
     
         6 . The method according to  claim 1 , wherein the aluminium alloy strip following the heat treatment is quenched to below 100° C. by moving the aluminium alloy strip over at least one rotating cooling roll, wherein the rotating cooling roll comprises an outer-surface, such that a surface of the aluminium alloy strip is in heat-transfer contact with the outer-surface of the rotating cooling roll to remove heat from the aluminium alloy strip to cool the aluminium alloy strip at a temperature below 100° C. 
     
     
         7 . The method according to  claim 1 , wherein the annealing temperature is in a range of 400° C. to 590° C. 
     
     
         8 . The method according to  claim 1 , wherein the heating roll has a diameter in a range of 1 to 3 meters. 
     
     
         9 . The method according to  claim 1 , wherein the heating roll is made from a metal, preferably selected from the group of cast iron, steel, stainless steel, copper, copper-based alloy, and aluminium alloy. 
     
     
         10 . The method according to  claim 1 , wherein the aluminium alloy strip has a thickness in a range of 0.3 mm to 4.5 mm, and preferably of 0.7 mm to 4 mm. 
     
     
         11 . The method according to  claim 1 , wherein the aluminium alloy strip has a composition within the AA2XXX-, AA5XXX, AA6XXX- or AA7XXX-series aluminium alloys. 
     
     
         12 . Facility for implementation of the method according to  claim 1 , characterised in that it comprises: a heating-section comprising two or more rotatable heating rolls adapted to move or transport in use an aluminium alloy strip while in heat-transfer contact with the outer-surface of the rotatable heating roll to induce heat into the aluminium alloy strip to heat the aluminium alloy strip at an annealing temperature; and a quenching section for rapid cooling or quenching of the aluminium alloy strip from the annealing temperature to below 100° C. 
     
     
         13 . Facility according  claim 12 , further comprising one of more screens positioned to face the side of the aluminium alloy strip that is not in heat transfer contact with the outer-surface of a rotatable heating roll to modulate the heat-loss of a moving aluminium alloy strip. 
     
     
         14 . Facility according to  claim 12 , wherein the outer-surface of the heating rolls is coated with a composite diamond coating.