Materials, Properties and Design

· This generic tensile test curve shows the sample shape at different deformation stages.
· In the elastic region the sample deforms uniformly, contracting laterally as it extends longitudinally.
· From the yield stress to the UTS, plastic deformation is a constant volume process: A₀L₀ = A_iL_i
· Beyond the UTS, deformation is local to the neck region until sample failure occurs by ductile fracture. This region is only stable at constant strain rate

From: Callister,
"Materials Science and Engineering,"
Wiley (1997)