To stably manufacture an Al alloy blank with high flatness for a magnetic disc.
In a method for manufacturing the Al alloy blank for the magnetic disk, which punches an Al alloy rolled sheet out into a blank, laminates several pieces of the blanks, pressurizes and anneals the blanks, this method is characterized by making the surface roughness of the blank before the above pressurization and annealing to be 0.35-0.60 μm in a transverse direction to the rolling direction. By making the surface roughness of the blank to 0.35 μm or more in the transverse direction to the rolling direction, the adhesiveness between the adjoining blanks is reduced, the blanks do not constrain thermal expansion or thermal shrinkage of each other when pressurized and annealed, and the blanks after pressurized and annealed are resistant to deformation and distortion. By making the surface roughness of the blank material to 0.60 μm or less, the ground amount after pressurizing and annealing is reduced, productivity thereby becomes excellent, and undulation on the ground substrate is hardly generated.
KITAMURA KAZUYUKI
IMAI KAZUTAKA
OZEKI YASUYUKI
