Fabrication of Nonporous Layer on Surface of ALPORAS by Friction Stir Incremental Forming

Porous metals having nonporous (skin) layer at the surface have a potential to improve the mechanical properties of the porous metals. To fabricate nonporous layer on surface of porous metals, friction stir incremental forming process is applied to form surface of a commercial closed-cell type aluminum foam (ALPORAS) in this study. In the process, the cell walls near the surface of the aluminum foam are plastically deformed by a rotating tool with a high rotation rate, fabricated the nonporous layer at the surface. The nonporous layer with thinner than 0.4 mm is fabricated at the surface without internal fracture of the aluminum foam under forming conditions of a tool rotation rate of 8000 rpm, a tool feed rate of 60 mm/min, and total forming depth of 7.0 mm.