Abstract
This investigation is carried out to develop the measuring apparatus which is suitable to measure internal friction in sintered material and find out the causes of internal friction in sintered iron material comparing with that in bar material.
Internal friction in sintered iron material increases greatly with the increase of stress amplitude and varies little with frequency. This is termed “hysteresis-type.” This internal friction is probably due to the large irreversible plastic deformation and small thermoelastic effect. Internal friction in Armco iron material increases greatly with the increase of frequency and increases a little with the increase of stress amplitude. This is termed “relaxation-type.”
Internal friction in Fe-C sintered materials decreases and shows the minimum value at 1%, and increases with the increase of carbon content. The decrease of internal friction with the increase of carbon content is due to the disappearance of ferromagnetism and the increase of the density. The increase of internal friction with the increase of carbon content is due to the increase of free carbon content and the decrease of the density.
