| The Ostwald ripening behaivor of carbide particles precipitated in 1-3% W steels at a temperature range from 660℃ to 700℃ has been investigated by using various quantitative metallographic examinations. The value for the slope of each straight line obtained from the relation between the log of the average particle size and the spheroidizing time is approximately 0.27 which indicates that the growth of precipitate particles in tungsten steels is mainly governed by the mechanism of non-volume diffusion. An average activation energy of 69.6 Kcal/mole for W steels was found, which was interpreted as an indication of the interdiffusion mechanism of Fe, C and W in steel. As the spheroidizing time increases, the carbides formed in the tungsten steel with an atomic ratio of 0.12 become a mixture of Fe₃C and WC. In the carte of tungsten steels with an atomic ratio of 0.25 and 0.36 respectively, however, the final stable carbide mixtures of Fe₃C and WC and formed after an intermediate stage where the semi-stable carbides of Fe₄W₂C and Fe_(21)W₂C type are coarsened. |
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