stainless steel foam is a low-density permeable material with 75-95% of its volume occupied by void spaces. It has been developed for a variety of applications such as cores for lightweight sandwich panels, vibration damping components, substrates for catalysts, filtration of molten metal alloys, etc. However, few studies on the energy absorption characteristics of stainless steel foam are available. In order to obtain more reliable results, it is necessary to consider the effect of pore structure in the energy absorption process of steel foams. In this article, we investigate the pore structure of steel foams prepared by powder metallurgy using urea as space holder and 316L stainless steel powder matrix. The effects of the pore size on the compressive stress-strain curve, yield strength, elastic modulus and plastic modulus were investigated.
The pore shape of the resulting steel foams is near spherical, and the relative density can be varied by changing the amount of urea used in the production process. The resulting metallographically polished and etched samples were analyzed using scanning electron microscopy (JEOL 5600).
The varying pore sizes and porosities of the fabricated steel foams have a significant influence on their stress-strain curve, yield strength and elastic and plastic modulus. The foams with larger pore size exhibit a higher yield strength and greater elastic modulus. The plastic deformation behavior of the steel foams with larger pore size is characterized by an initial elastic deformation phase followed by a long plateau region due to the elastic collapse of the cells, and finally a densification strain in which the cell is compacted and stress increases rapidly.