Nondestructive Evaluation of Sintered Iron Using Dynamic Young’s Modulus Testing

In this study, the model in which Young’s modules(E) depends on only porosity (P) was investigated by the experimental results of sintered iron, and new equation of Young’s modulus against porosity was derived. The equation was confirmed by applying to the relationship between Young’s modulus and porosity obtained by the acoustic pulse method and the resonance frequency method. The derived equation is E(P)=E₀(1-k_E·P)·(1-P), where k_E and E₀ are a positive constant and E at P=0, respectively. This equation shows that the term of 1-P represents the porosity effect and the term of 1-k_E·P represents the pore morphology effect, such as shape, size and interconnection of pores. Furthermore, for P below 0.2, a new nondestructive method to calculate partial porosity and propagation distance, such as defect depth and sample thichness, was developed by using of the ratio of longitudinal wave velocity to shear wave velocity obtained by the acoustic pulse method.