Electrical conductivity and microstructure of sintered ferrous materials: sintered iron

The viability of electrical conductivity as a tool for describing the microstructure of sintered iron compacts was investigated, the sintering temperature being varied from dewaxing to high temperature sintering. The relationships between formation of sintered contacts, presence of lubricants, and mechanical properties were evaluated through determination of conductivity and effective load bearing cross-section Ac. The latter parameter was measured via quantitative fractography of specimens impact fractured at 77 K. The role of porosity and sintering temperature on grain growth in iron was also evaluated using quantitative metallography. It was found that the conductivity of pressed compacts increases during the dewaxing stage, while the effect of the sintering parameters at higher temperatures is less conspicuous. In any case, the conductivity can be related to the load bearing cross-section by a logarithmic equation. Using the already established relationships between Ac and the mechanical properties, the latter can be predicted by using the conductivity, which might be helpful in quality control of PM components.