Study of the mechanical properties of porous iron in tension and torsion

Elastic and plastic properties of powder materials: a continuum model

“…In turn, the initial density of a powder before compaction is bulk density, while the effective volume α of a porous sintered material is calculated assuming that its initial density ρ 0 is equal to bulk density. This conclusion is confirmed by experimental data in [12] where zero values of elastic moduli of sintered iron obtained by extrapolation correspond to the bulk density of iron powder. In the literature, however, one can find mainly the densities of sintered materials and very rarely the bulk density of powders.…”

“…Experiments, however, discovered that the elastic moduli of porous materials become zero or nearly zero at nonzero density. For example, according to [12], the elastic moduli of porous materials become infinitesimal at ρ = 0.227. Porous materials are produced by partial sintering of powders after cold compaction.…”

“…Let the volume α become zero once open porosity has formed. If the pores are (6); 2) formula (7); 3 and 4) formula (4) with ρ 0 = 0 and ρ 0 = 0.26, respectively; circles = experiment [12] equal spheres, the maximum closed porosity θ max = 0.74, which corresponds to the close packing of balls with highest density. Therefore, in the absence of information on the bulk density of porous sintered materials, we can assess the initial density at which the elastic properties start showing up from the volume fraction θ max of the skeleton as ρ 0 = 1 -θ max = 0.26.…”

“…This allows reducing the number of phenomenological parameters in the model and the labor intensity of the experiment. (10); 2) α = ρ, density functions (11); 3) α = ρ, density functions (12); circles = experiment [18] and extrapolation of (19) (10); 2) α = ρ, density functions (12); 3) calculated data [15], circles = experiment [15] (10); 2) α = ρ, density function (12); 3) calculated data [15]; circles = experiment [15] The calculated values of the phenomenological constants confirm the leading role of the density functions in the description of the plastic properties of powder materials. These functions define the density dependence of the elastic moduli and the limiting elastic state of a powder.…”

“…4. The calculations used the plasticity condition (8) with density functions (10) and the equality α = ρ with density functions (11) and (12). The compaction via interparticle slip is described well by the formulas with the density functions (10) and (12).…”