Durable aluminium alloy sheet for decorative applications

Abstract

The invention relates to improved sheets for decorative and formable parts made of an aluminium alloy which comprises, in wt. %, Mg: 0.8-1.3, Mn: 0.8-1.2, Cu: 0.05-0.30, Cr: 0.05-0.30, Fe: ≤0.4, Si: ≤0.3, Zn: ≤0.25, Ti: ≤0.15, impurities<0.05 each and <0.15 total, remainder aluminium. The method to make a sheet according to the invention comprises casting a slab with a composition according to the invention, homogenizing, hot and cold rolling the slab, annealing and tension leveling. The sheet according to the invention are particularly useful to make a coated decorative part preferably a decorative part for an automobile, or a household appliance or a medical device.

1 . A sheet comprising an aluminium alloy, said alloy comprising, by weight %
 Mg: 0.8-1.3,   Mn: 0.8-1.2,   Cu: 0.05-0.30,   Cr: 0.05-0.30,   Fe: ≤0.4,   Si: ≤0.3,   Zn: ≤0.25,   Ti: ≤0.15,   impurities<0.05 each and <0.15 total, remainder aluminium.   
     
     
         2 . The sheet according to  claim 1  comprising by wt. % Cr: 0.10-0.30 and optionally Cr: 0.15-0.25. 
     
     
         3 . The sheet according to  claim 1  comprising, by wt. %, Fe: 0.15-0.35 and/or Si: 0.10-0.25. 
     
     
         4 . The sheet according to  claim 1  comprising, by wt. %, Mg: 0.9-1.1. 
     
     
         5 . The sheet according to  claim 1  comprising, by wt. %, Mn: 0.85-1.15 and optionally Mn: 0.95-1.05. 
     
     
         6 . The sheet according to  claim 1  comprising, by wt. %, Cu: 0.10-0.25 and optionally Cu: 0.15-0.20. 
     
     
         7 . The sheet according to  claim 1  wherein TYS in a longitudinal direction is at least 130 MPa and A % in a longitudinal direction is at least 13%. 
     
     
         8 . The sheet according to  claim 1  wherein, after a thermal treatment of 4 min at 195° C. TYS in a longitudinal direction is at least 110 MPa and A % in a longitudinal direction is at least 16%. 
     
     
         9 . A method to make a sheet according to  claim 1  comprising,
 (a) Casting a slab of an aluminium alloy comprising, by weight %
 Mg: 0.8-1.3, 
 Mn: 0.8-1.2, 
 Cu: 0.05-0.30, 
 Cr: 0.05-0.30, 
 Fe: ≤0.4, 
 Si: ≤0.3, 
 Zn: ≤0.25, 
 Ti: ≤0.15, 
 impurities<0.05 each and <0.15 total, remainder aluminium, 
 
 (b) homogenizing the slab at a temperature of at least 550° C. to a homogenized slab, 
 (c) hot rolling the homogenized slab to an intermediate rolled product having a thickness from 3 to 10 mm, 
 (d) cold rolling the intermediate rolled product into a sheet, optionally with an intermediate annealing during cold rolling, 
 (e) annealing the sheet at a temperature from 300° C. to 400° C. and tension leveling the sheet with a stretching of at least 1%. 
 
     
     
         10 . A product comprising a sheet according to  claim 1  for a coated decorative part, optionally a decorative part for an automobile, or a household appliance or a medical device. 
     
     
         11 . The product according to  claim 10  for an automobile interior finishing element selected in the group consisting of a door handle, a gearbox trim, a trim element for a center console, a trim for a dashboard, a panel for a dashboard, a trim for a door, a panel for a door and a capacitive function element or an automobile exterior element selected in the list consisting of a window surrounds, a body side or door trim strip, a tailgate trim strip, a radiator grille trim, wheel hub cover, a beltline and a bumper piping.