<Original Papers>On the Effect of Alloying Elements on the Solubility of Carbon in Molten Iron

The solubility of carbon in Fe-C-Si, Fe-C-Cr, and Fe-C-Mn melts was determined at 1,540℃. Some considerations were made to generalize the effect of alloying elements on the solubility of carbon in molten iron, refering to the previous data of other works of ours on the solubility of carbon and nitrogen in iron alloys. And then, the factors which are responsible for these effects have been discussed in relation to the Periodic Table, and the following regularities were recognized : 1) The solubility of carbon in iron melts containing the solute of the Second Short Period ; Al, Si, P, and S, decreases as the atomic number of the solute increases. 2) The same arrangement is found in the First Long Period ; Ti, V, Cr, and Mn increase the solubility of carbon in iron, whilst Co, Ni, and Cu decrease it. Further, as regards the carbon solubility of iron melts containing multiple solute, the following theoretical equation was deduced approximately at the dilute concentration of solute X_i : [numerical formula] where ΔNc is the difference between the solubility of carbon in Fe-C (N^O_C) and in Fe-C-X_i-X_j… (N_C), N_ is the atom fraction of solute X_i, and ε^_C represents the interaction parameter defined by ∂lnγC/∂N_. In order to confirm the adequacy of this equation, the solubility of carbon in Fe-C-Cr-Si and Fe-C-Mn-Si melts was determined at 1,400℃