Abstract
Medium and low-density sintered iron compacts usually have many pores, which size and shape are various. In the present paper the influence of these pores upon the fatigue strength has been investigated.
For the fatigue fracture of the medium and low-density sintered iron compacts, the following conclusions were obtained from microscopic observations.
1) Cracks generate from the pores with sharp edges and from the pseudo boundaries, without generation of slip bands in a crystal grain.
2) These cracks generate later than in the case with high density sintered iron compacts and once the cracks generate, they grow rapidly.
This tendency becomes stronger, in the case of fatigue fracture under low stress.
