| In a dilute ternary stolid solution of alpha iron which contains a substitutional solute M and an interstitial solute I, the equilibrium amount of substitutional-interstitial dipoles M-I at a temperature T is given by the following equation: x/y=[6θ_M/(1-θ_M)]·exp[-(ε¹-ε＾0)/kT] (1) where x is the molar fraction of solute I combined with solute M to form M-I dipoles, y is the molar fraction of solute I existing as single atoms, θ_M is the molar fraction of substitutional solute M, (θ¹_ε＾0) is the binding energy between M and I, and k is the Boltzmann constant. The binding energy of carbon with manganese is -0.27 eV and that of carbon with chromium is-0.3 eV. In a case of aluminium-killed low-carbon steel, the solubility of total carbon (x + y) in the alpha-iron phase is log_(10) [100(x+y)]=-(3300/T)+f where f= 2.27 for θ_(Mn) = 0.002 and f= 2.34 for θ_(Mn) = 0.004. (2) Substitutionl-interstitial dipoles are supposoed to inhibit the motion of dislocations for recrystallization in cold-rolled steels. The presence of Mn-C or Cr-C dipoles have a marked effect on the recrystallization texture of low-carbon sheet steels. The effect is more pronounced in the case of Cr-C dipoles than in the case of Mn-C dipoles. The amount of substitutional-interstitial dipoles which exist just before the commencement of primary recrystallization is important for the control of the recrystallization texture in low-carbon sheet steels. Although our knowledge of substitutional-interstitial dipoles is still unsatisfactory, I feel we are approaching to a quantitative treatment of the effects of alloying elements on the recrystallization texture of sheet steels. |
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