Poisson's Ratio of Sintered Materials for Structural Machine Parts

The relationships between Young's modulus, shear modulus and Poisson's ratio of sintered materials and porosity were investigated for use as practical P/M machine parts. Three types of steel powders were prepared and then compacted, sintered, and heat-treated under various conditions. Porosity had the greatest influence on Young's modulus, shear modulus, and Poisson's ratio. Especially, Poisson's ratio was affected by the pore shape, which depended on the type of powder, sintering temperature and atmosphere, and heat treatment.For the more practical use of powder compositions, there was little influence by the sintering atmosphere on the Poisson's ratio of the sintered and heat-treated materials. For a partially alloyed powder (Fe-4mass%Ni-1.5 mass% Cu-0.5 mass%Mo)+0.8mass%C powder, Poisson's ratio versus porosity depended only on the sintering temperature at a porosity below 20%. In this case, a simpler approximate equation of Poisson's ratio of the sintered and heat-treated specimen versus porosity was proposed as follows: ν=0.300-0.266P+0.579P2 at 1423 K (sintering temperature) or ν=0.304-0.264P+0.548P2 at 1523K