To provide a substrate for lithographic plate, uniform in material, free from dispersion of electrolytic surface roughening property, and remarkably improved in bending strength, and its production.
This aluminum alloy substrate is composed of an aluminum alloy sheet having a composition containing, by weight, >0-0.20% Fe, >0-0.13% Si, and ≥99.7% Al and can be obtained by rolling molten aluminum directly into sheet-like state by means of twin roll, rolling this sheet to 0.5-0.1mm by means of cold rolling, performing straightening, and subjecting the resultant aluminum substrate 12 to surface roughening. Further, in the cutting surface 12a perpendicular to the direction of advance of the rolling, the thickness T and the width W of the crystalline grains located in the position at a depth of ≥5μm from the surface layer are regulated to 20-100μm and 100-5000μm respectively.
SAKAKI HIROKAZU
MATSUURA KINYA
