Litho strip and method for its manufacture

A litho strip for electrochemical roughening comprising a rolled aluminum alloy, said aluminum alloy comprising, in addition to any impurities from manufacture:

• aluminum;
• 0.30-0.40% iron;
• 0.15-0.30% magnesium;
• 0.05-0.15% silicon;
• not more than 0.01% manganese;
• not more than 0.005% copper;
• not more than 0.01% chromium;
• not more than 0.02% zinc;
• not more than 0.01% titanium;
• not more than 50 ppm boron;
• and,
• if said alloy comprises any impurities resulting from manufacture, said impurities, in sum, amount to less than 0.05% of said alloy, wherein:
• said litho strip has a rolling direction;
• said litho strip has a reversed bending fatigue strength perpendicular to said rolling direction, said reversed bending fatigue strength having a value greater than 1,250 cycles in a reversed bending test;
• and
• said litho strip, after test annealing at 240° C. for 10 minutes, has a tensile strength, Rm, greater than 145 N/mm2.

A method for producing a litho strip comprising:

• producing a rolling ingot of a thickness greater than 500 millimeters from an aluminum alloy, said aluminum alloy comprising in addition to impurities resulting from manufacture:
• aluminum;
• 0.30-0.40% iron;
• 0.10-0.30% magnesium;
• 0.05-0.25% silicon;
• not more than 0.05% manganese;
• and
• not more than 0.04% copper, wherein:
• said producing comprises:
• continuous casting;
• and
• homogenizing at a temperature in the range 480-620 degrees centigrade for no less than two hours;
• hot rolling said rolling ingot into a hot rolled strip wherein:
• said hot rolling comprises a last hot rolling pass, said last hot rolling pass reducing the thickness of said hot rolled strip by 15 to 75%;
• said hot rolling has a hot rolling end temperature of greater than 250 degrees centigrade;
• and
• said hot rolling causes said hot rolled strip to have a thickness of 2-7 millimeters;
• cooling said hot rolled strip to room temperature to produce a cooled hot rolled strip, said cooled hot rolled strip having a surface, globulitic recrystallized grains, and a residual resistance ratio RR, said grains being disposed in said surface and having an average diameter of less than 50 microns, and said residual resistance ratio having a value in the range 10-20;
• cold rolling said cooled hot rolled strip to form a cold rolled strip;
• and
• further processing said cold rolled strip prior to electrochemical roughening, said cold rolled strip having a microstructure formed during said hot and cold rolling and a temperature less than 100 degrees centigrade, while maintaining said microstructure and said temperature, wherein said further processing is selected from the group consisting of:
• a. stretching;
• b. degreasing;
• c. cutting;
• d. pickling;
• and
• a combination of any of (a)-(d).