抄録
To investigate the effect of C and Nb on the strength and thermal expansion of Fe-Ni-Nb-C alloys, an analysis was made by using an equation about solubility product of NbC. Good agreement was found between the weight of extracted residue and that of calculated NbC. Specimens were cold drawn (ε=ln(S0/S)=2.77) and various properties were measured. The results obtained are as follows:
(1) Both carbon and niobium in solid solution increase tensile strength of Fe-Ni-Nb-C alloys.
(2) Carbon in solid solution increases the mean thermal expansion coefficient at low temperature range between 30 and 100°C. While niobium in solid solution increases the thermal expansion coefficient at high temperature range between 200 and 300°C, corresponding to the decrease of Curie temperature of the alloys.
(3) Thermal expansion coefficient decreases by cold drawing. Effect of carbon in solid solution is remarkable on the decrease of the thermal expansion coefficient at the temperature range between 100 and 200°C.
(4) Following linear regression equations are obtained between properties and chemical compositions.
σB(kg/mm2)=84.0+180[%C]γ+8.6[%Nb]γ+5.8[%NbC](at ε=ln(S0/S)=2.77)
ρ(μΩ·cm)=-89.7+3.72[%Ni]+5.51[%Nb]γ
σS(emu/g)=157.2+0.60[%C]γ-5.46[%Nb]γ-0.17[%Ni]
where σB is tensile strength, ρ is electrical resistivity and σS is saturation magnetization. [%C]γ and [%Nb]γ represents weight percentage of carbon and niobium in solid solution respectively.
