Compaction of porous powder body consisting of the elastic­plastic medium

Abstract

In the development of technological processes of producing cold-pressed sintered parts of low porosity, special attention is paid to the mechanism of density variation. In powder metallurgy, a multicomponent charge consisting of plastic metals, as well as poorly compressible inclusions and compounds, is often used. Such charge can equally be attributed to the charge consisting of iron powder, cast iron and glass. In this charge, the first component (base) is ductile iron, and the other two, cast iron and glass, are elastic components. It is of some interest what kind of compaction can be obtained in this case and what resulting equations can be used to estimate the mechanics of compaction of such a powder charge. The resulting equations of compaction of porous powder bodies of iron-cast iron-glass are proposed. The analysis of the isotropic, rigid-plastic hardening material such as iron-cast iron-glass is given. When compacting such a material, the rate of energy dissipation (pressing pressure) is determined by the rate of volume and form change of the body. It is shown that the difference between compressed (cast iron and glass) and plastic compacted (iron) materials forms special mechanical properties of the matrix. Consequently, hydrostatic pressure can affect the form change of the body, and shear stresses – volume change. The results of the mathematical approach to obtaining the resulting equations of compaction of the elastic-plastic medium showed the way to build a theory of plasticity of the compacted body, which eliminates the need to take into account the type of loading surface. When accounting the loading surface, it is impossible to obtain universal equations of compaction of the porous elastic-plastic medium. It is shown that to apply the classical formulation of the model of the elastic-plastic compacted body, it is necessary to assume that the loading surface is convex-closed