Superplastic Forming and Foaming Process for Porous Aluminum Plates

Abstract

A new application of superplasticity has been developed in the field of porous metals. Porous metals manufactured through a liquid-state foaming process often include large pores and inhomogeneous pore distribution which decrease in the mechanical properties. A solid-state foaming process enables to suppress the collapse and coalescence of pores, but high porosity is not achieved due to the large flow stress. Superplastic flow during the solid-state foaming is effective to accelerate the foaming rate and to increase the porosity. Superplastic 5083 aluminum alloy sheets are used as a starting material for manufacturing of porous aluminum. A preform plate containing titanium hydride particles as a foaming agent is produced through roll-bonding processing. Porous aluminum with small pores and relatively high porosity is manufactured through superplastic foaming process. A thin sandwich panel with a porous aluminum core and porous bulge structures can be manufactured by utilizing the superplastic flow. This technique of superplastic forming and foaming (SPFF) processing has a potential for near net-shape forming as well as evaluation of the solid-state foaming of porous metals.