Strain rate sensitivity and defects in steel foam

Steel foams fabricated by a powder metallurgical process were subjected to uniaxial compression tests to explore the dependence on strain rate. The yield strength of foam samples showed stronger strain rate dependence at higher strain rates, while the energy absorption increased linearly with strain rate. Measurements of cell wall curvature showed that an increased mean curvature correlated with a reduction in yield strength, and foam strengths generally fell below predictions of the Gibson–Ashby theory. Morphological defects (corrugations of cell walls) also reduced yield strength and altered the dependence on density.