焼結体の引張り強さと気孔率のの関係(I)

抄録

The relationship between the tensile strength and porosity in sintered compacts has been investigated by using electrolytic iron powders. It was shown that the variation in the tensile strength with the porosity (or density) could be expressed separately in three stages, that is, the low density region, the middle density region, and the high density region. The relations of tensile strength and porosity in those three regions can be represented by the following forms.
For the low density region,
S=S'₀-k₁P (P₁<P≤P_O)
where S is the tensile strength, P, the porosity, P_O, the green porosity, and S'₀, k₁ and P₁, empirical constants. For the middle density region,
S=S'₀ exp(-bP) (P₂<P≤P₁)
where S is the tensile strength, P, the porosity, and S_O, b, P₁ and P2, empirical constants. For the high density region,
S=(S _s+k ₂G^-1/2)exp(-bP) (P≤P ₂)
where S is the tensile strength, G, the grain size, P, the porosity, and S₈, K₂, b and P₂, empirical constants, if the grain size can be represented as a function of porosity,
S=(S_s+k₃P^a)exp(-bP) (P≤P₂)
where S is the tensile strength, P, the porosity, and S₈ k₃, a, b and P₂, empirical constants.
The empirical constants contained in the above forms were determined by the experimental results. Then, the following forms representing the relations of tensile strength and porosity for the sintered electrolytic iron powder were obtained. When the compressing pressure is 4 t/cm², for the low density region,
S=132-495P [kg/mm²] (0.23<P≤0.27).
For the middle density region,
S=43.0 exp(-4.4P) [kg/mm²] (0.085<P≤0.23).
For the high density region,
S=(29.5+1.05G^-1/2) exp(-4.4P) [kg/mm²] (P≤0.085)
where C is in mm, and
S=(29.5+62.5P^0.62) exp(-4.4P) [kg/mm²] (P≤0.085).