In this study, the relationships between porosity and Young's moduli measured by an acoustic pulse method, a resonance frequency technique, a tensile test and a bending test of sintered irons were investigated. Moreover, tensile strength and proof stress were measured by tensile test, and these values and Young's modulus were evaluated against porosity.
Young's moduli measured by the acoustic pulse method, resonance frequency technique and tensile test, except for the bending test, were nearly equal at the same porosity. In the case of the bending test, the moment of inertia of the area was a linear function of porosity. Young's modulus measured by the bending test, which was corrected by use of the above relation, was equal to that by other method. Young's modulus measured by the bending test was 0.7-0.8 times of Young's modulus measured by the tensile test.
Young's modulus (E), tensile strength (T_s) and proof stress (P_s) against porosity (P) are expressed as E=(E₀-K_E⋅P) (1-P), T_s=(T_so-K_Ts⋅P)(1-P) and P_s=(P_so-K_ps⋅P)(1-P), respectively. Here, E₀, T_so and P_so are Young's modulus, tensile strength and proof stress at P=0, and K_E, K_TS and K_PS are the experimental coefficients of each relation. Moreover, we found that the relationships among Young's modulus, tensile strength and proof stress are in positive correlation.