Formability of superplastic aluminum alloy composites reinforced with SiC particles

Superplastic aluminum alloy (SPA) composite sheets reinforced with SiC particles (of 5 or 20 μm in diameter) are fabricated by the hot pressing method. After discussing the effects of SiC particle size and hot pressing conditions on the mechanical properties of the composite sheets, their formability under tensile stress fields (uniaxial, plane strain and balanced biaxial) and deep drawability using the local heating and cooling deep-drawing method are estimated at 803 and 808 K, respectively, temperatures at which the matrix material exhibits superplasticity. However, deep drawing is indicated even at 753 K. A forming-limit diagram is constructed on the basis of the experimental results. The maximum and minimum limits of stretch formability are revealed in the areas of uniaxial tension and balanced biaxial tension (by punch bulging). However, in gas pressure stretch forming (balanced biaxial tension) without friction, the stretch formability is equal to or greater than that under uniaxial tension. As an example of deep-drawing results, the drawing ratio of the metal matrix composite sheets containing SiC particles (of 20 μm in diameter and 25 mass%) reached 2.18 using the local heating and cooling deep-drawing method.