The internal friction of the pearlitic, bainitic and martensitic transformations in Fe [sbnd]Ni [sbnd]C alloys

Abstract

The low frequency internal friction of the pearlitic, bainitic and martensitic transformations in three Fe Ni C alloys has been studied. The results show that the internal friction of the martensitic transformation is in correspondence with the model based on the hysteresis loss mechanisms associated with stress-induced motion of the interface dislocations, while that of the pearlitic and bainitic transformations obeys Postnikov's model. At a constant frequency, the internal friction peaks of the pearlitic and bainitic transformations increase as the cooling rate increases, but the temperature of the internal friction peaks decreases, and the Q max −1 is directly proportional to the T/ f mT m. When the frequency increases, the Q max −1 of the pearlitic and bainitic transformations lowers apparently, and the temperature of the internal friction peaks increases. The internal friction of the isothermal bainitic transformation in a Fe Ni C alloy has also been studied, which proves that there appears a damping peak in the incubation period, and which may be attributed to the nucleation of bainite. Consequently it infers that the mechanism of the bainite reaction seems similar to that of pearlite.