Cup and Cone Fracture

When a circular wire, rod or round tensile test specimen is stressed (in tension/pulling) beyond the yield point (or yield strength) the metal will become plastic and will “flow” at the weakest location.  The circular cross section at this location will be diminished (necking).  As the stressing/pulling continues, the metal will separate or fail at this location. The resultant fracture will have a characteristic appearance.  One side of the fracture will appear to be a cup and the mating (pointed) fracture will appear to be a “cone”.  This type of tensile overload fracture is referred to as “cup and cone”.