Tensile Behavior and Performance of Syntactic Steel Foams Prepared by Infiltration Casting

Syntactic steel foams (SSFs) were prepared by low-pressure infiltration of molten ASTM CF-8 cast austenitic stainless steel into randomly and densely packed Al2O3 hollow spheres. The microstructure of the SSFs was characterized by scanning electron microscopy and energy dispersive spectrometry. Using dumbbell-shaped specimens, the density of the as-cast SSFs is measured in the range from 3.33 to 3.64 g/cm(3) and their ultimate tensile strength from 83.1 to 97.6 MPa. No significant chemical reaction was detected between the fillers and matrix. The quasi-static uniaxial tensile deformation of the syntactic foams underwent elastic deformation, plastic deformation, and then a failure stage, showing similar tensile behavior to plastic bulk metals but different behavior to common metal foams. From the good ductility of the metal matrix, a clear macroscopic plastic deformation was observed before the ductile fracture of the syntactic foams. A constitutive relationship of the SSFs under uniaxial tensile loads has been proposed.