| This work was undertaken to study the effect of degree of working applied during the drawing on spheroidization of cementite in 0.74%C steel wire. The effect of drawing was evaluated by the particle size of spheroidized cementite. Particle size of spheroidized cementite was calculated by Fullman method, replacing the number of particles per unit area counted in photomicrograph. Specimens of steel wire were prepared by cold drawing from 4.0㎜ to 2.8, 2.0, 1.4 and 1.0㎜ in diameter, and annealed at temperatures between 640° and 730℃ for various times up to 45 hours, From this experimental results, it was found that the spheroidization of cementite was controlled by diffusion, and also the effective diffusion coefficients were increased with increasing amount of cold work. The activation energy for the spheroidizing was found to be 40 ㎉/mole. The results may be rationalized by the theory proposed by Liishitz-Wagner. |
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