Effects of Porosity on Elastic Moduli and Poisson's Ratio of Sintered Irons.

A systematic study of the variation of elastic moduli and Poisson's ratio of sintered iron compacts of porosity (up to 0.6) has been carried out by measuring longitudinal and shear wave velocities. In this study, new equations of Young's modulus (E), shear modulus (G) and Poisson's ratio (v) as function of porosity (P) were proposed as follows ; E (P) = (-KE·P+E0)·(1-P) G (P) = (-KG·P+G0)·(1-P) v (P) =0.5 (-KE·P+E0)/(-KG·P+G0)-1 where KE and KG are experimental constants of Young's modulus and Shear modulus, respectively. And E0 and G0 are Young's modulus and shear modulus at P=0, respectively. In these equations, KE, KG, E0 and G0 at P≨0.2 are different from those at P<0.2. Because the results of Poisson's ratio against porosity of sintered iron compacts show that downtrend of Poisson's ratio at P>0.2 was different from at P≨0.2. The downtrend change is caused by pore connection as connecting pores increase and closed pores decrease at P≨0.2. The fitting data of Poisson's ratio by these equations correspond with the measurement data by comparison with the published equations of many researchers.