<研究論文>焼結鉄の弾性率に及ぼす気孔率および気孔形状の影響

概要

論文の詳細を見る
The relationships among elastic modulus, sound velocity, porosity (P) and pore shape were investigated by theoretical elastic model and experimental results obtained by acoustic pulse method. Young's modulus and shear modulus decreased with increasing P as (E_0-K_E・P)・(1-P) and (G_0-K_G・P)・(1-P), respectively. Where E_0 and G_0 are E and G at P=0,respectively, K_E and K_G are experimental constants. The square of sound velocity was as a function of P. In these relations, the experimental constants of elastic modulus and sound velocity changed at critical porosity where pore morphology changes. By considering of the critical porosity to the fitting curve calculated using the equation derived in this study, good agreement with measured data of Poisson's ratio was obtained. Furthermore, for P below 0.2,a new nondestructive method to calculate partial porosity and propagation distance, such as defect depth and sample thickness, was developed by using of the ratio of square of longitudinal wave velocity to square of shear wave velocity.