Microstructure and compressive deformation behavior of SS foam made through evaporation of urea as space holder

Abstract

Abstract Open cell 316L stainless steel foam (SSF) of varying porosities have been developed through powder metallurgy route using evaporative spherical urea particles (UP) as a space holder. Stainless steel powders (SSP) were cold compacted under 500 MPa pressure and sintered at 1200 °C for 1 h in a high vacuum atmosphere (10−4 mbar). Detailed Energy dispersive X-ray spectroscopy (EDS) analysis and X-ray diffraction pattern (XRD) conformed that no residue of space holder (urea) in sintered samples. The compressive deformation behavior of sintered foam samples with varying relative densities (ρrd) was conducted at 0.01s−1 strain rate. The yield strength, elastic modulus (Ef), plastic modulus, average plateau stress (σpl) and energy absorption (Eab) of the foam increases with increases in the relative density and these follows power law relationship with relative density. On the other hand, densification strain (ɛd) decreases with increases relative density. This has been discussed with the deformation mechanism of the stainless steel foam (SSF). Deformation of SSF is associated with cell wall (CW) bending, CW collapse due to bulking followed by shearing and facture of cell wall layer by layer.