Damping capacity is a very sensitive character of the internal structure as is clearly evidenced by the damping changes that occur when the shape of graphite in cast iron is altered. However, a limited amount of work has been carried out on the damping of sintered irons.
In this paper, the characteristics of the damping capacity of sintered irons are investigated and some factors affecting it are discussed by observing the micro-structure of the specimens. The damping capacity was measured by the transverse-vibration method at strain-amplitudes ranging from 2×10^-6 to 1×10^-4.
The results obtained were as follows: The damping capacity observed on a sintered iron can be separated into two parts; the amplitude independent part (Q_L^-1) and the amplitude dependent part (Q_H^-1). Magni-tude of Q_L^-1 decreases with an increase of the density, sintering temperature and time, and it corresponds to the degree of sintering. Q_H^-1 showes a well-defined amplitude dependence, that is, it increases linearly with the strain-amplitude. The origin of Q_H^-1 is due mainly to the magneto-mechanical static hysteresis in ferrite. A specimen machined by grinding or repressed exhibits as high damping capacity as flaky cast iron. This may be caused by the existence of some elongated pores produced by machining.