Effects of pore characteristics on elastic modulus and Poisson's ratio of sintered irons.

Relationships between Young's modulus, shear modulus, Poisson's ratio and porosity of sintered irons have been studied by an acoustic pulse method at varying of pore shapes, sizes and distributions. The pore shapes, sizes and distributions were changed by using reduced iron powder, atomized iron powder, sieved atomized iron powder, and mixed powder of carbonyl iron powder and atomized iron powder, or by the process of re-compacting and resintering.In all case, the Young's modulus, the shear modulus and the Poisson's ratio decreased with increasing of porosity. At the same porosity, spherical and fine pores increased the Young's modulus and the shear modulus, decreased the Poisson's ratio by comparison with irregular and coarse pores. The Young's modulus, the shear modulus and the Poisson's ratio increased as pore surface becoming smooth.In case that pore shapes are similar and pore sizes are different, the Young's modulus and the shear modulus having fine pores are higher than that having coarse pores. Although pore shapes, sizes or distributions of sintered irons were different, at the same sintering conditions the Poisson's ratios were nearly equal at the same porosity (<0.2).