Low-density clad steel sheet having excellent formability and fatigue property and manufacturing method therefor

A method of manufacturing a low-density clad steel sheet having excellent formability and fatigue properties, comprising:

• preparing a base material, a lightweight steel sheet including, by weight, C:
• 0.3 to 1.0%, Mn:
• 4.0 to 16.0%, Al:
• 4.5 to 9.0%, and a remainder of Fe and inevitable impurities;
• preparing cladding materials, each of which is martensitic carbon steel including, by weight, C:
• 0.1 to 0.45%, Mn:
• 0.1 to 3.0%, and a remainder of Fe and inevitable impurities;
• disposing the base material between two of the cladding materials to obtain a laminate;
• welding an edge of the laminate, and heating the welded laminate to a temperature within a range of 1050 to 1350° C.;
• finish-rolling the heated laminate to a temperature within a range of 750 to 1050° C. with a rolling reduction ratio of 30% or more in a first pass, to obtain a hot-rolled steel sheet;
• coiling the hot-rolled steel sheet at a temperature within a range of 400 to 700° C.;
• pickling the coiled hot-rolled steel sheet, and applying a cold-reduction ratio of 35 to 90% thereto to obtain a cold-rolled steel sheet;
• and
• annealing the cold-rolled steel sheet at a temperature in a range of 550° C. or higher and A3+200° C. or lower of the cladding materials.