Page "Necking (engineering)" Paragraph 1

' Necking ', in engineering or materials science, is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material.

The resulting prominent decrease in local cross-sectional area provides the basis for the name " neck ".

Because the local strains in the neck are large, necking is often closely associated with yielding, a form of plastic deformation associated with ductile materials, often metals or polymers.