Machine design why do the fracture surface of ductile metals

Machine design

why do the fracture surface of ductile metals in tensile failure appear as cop-cone shape?

Solution

solution :

In ductile fracture, extensive plastic deformation (necking) takes place before fracture. The terms rupture or ductile rupture describe theultimate failure of tough ductile materials loaded in tension. Rather than cracking, the material \"pulls apart,\" generally leaving a rough surface. In this case there is slow propagation and an absorption of a large amount energy before fracture

Because ductile rupture involves a high degree of plastic deformation, the fracture behavior of a propagating crack as modelled above changes fundamentally. Some of the energy from stress concentrations at the crack tips is dissipated by plastic deformation before the crack actually propagates.

The basic steps are: void formation, void coalescence (also known as crack formation), crack propagation, and failure, often resulting in a cup-and-cone shaped failure surface