Ductile fracture in metals

Cup-and-cone fracture in single-phase ductile metals appears to originate at holes formed by drawing away of material from non-metallic inclusions, as suggested by Tipper. In copper, the holes expand under the triaxial stresses in the neck and coalesce in a macroscopic fissure; in α iron fine cracks are formed by the stress concentrated at the holes. In coarsegrained material shear cracks are formed on the surface of the neck. Pure...