Method of annealing aluminium alloy sheet material

A method for continuously annealing aluminium alloy sheet at final thickness, comprising:

• continuously moving uncoiled heat-treatable AlMgSi aluminum alloy sheet, having a sheet thickness, in the direction of its length through a continuous annealing furnace arranged to heat the moving aluminium sheet to a set soaking temperature (TSET) in a temperature range of 500° C. to 590° C., the continuous annealing furnace has an entry section and an exit section, wherein the moving aluminium sheet moves substantially horizontally through the continuous annealing furnace,
• wherein the continuous annealing furnace is heated by convective heating, and
• wherein the moving aluminium sheet is rapidly cooled from TSET to below about 100° C. on leaving the exit section, and
• wherein before or near the entry section of the continuous annealing furnace the moving aluminium sheet is pre-heated to a temperature of 5° C. to 100° C. below the TSET using an average heat-up rate as function of the sheet thickness of at least Y=−31·ln(X)+50, wherein “Y” is the heat-up rate in ° C./sec and “X” is the sheet thickness in mm.