THE MECHANISM OF DUCTILE RUPTURE OF METALS CONTAINING INCLUSIONS

The role of inclusions in ductile fracture was examined on an experimental and theoretical basis. Microscopic observations showed that inclusions or precipitates are often the source of cracks which lead to ductile rupture. Three different stages may be supposed for this type of ductile rupture: 1) formation of cracks at inclusions, 2) growth of the cracks, and 3) internal striction leading to failure. The major part of the elongation takes place during the second stage. The stresses which are developed around inclusions are described. The elongation to rupture was calculated on the basis of quite simple assumptions, and it is shown that, for a given material, it depends primarily on the volume fraction of the particles. Fair agreement was obtained between the results calculated from the theory and the experimental data on copper-base composite alloys reported by Edelson and Baldwin. (auth)