The stress that must be applied to a material to make it begin to flow (or to yield). Yield stress is a parameter in the Herschel-Bulkley rheological model.

The stress level of highly ductile materials, such as structural steels, at which large strains take place without further increase in stress.

A stress at which a steel exhibits the first meas-urable permanent plastic deformation

Stress limit within a material at which plastic (permanent) strain commences under load.

A material loaded beyond its yield stress, no longer exhibits linear elastic behavior. Metals, particularly mild steel, generally have a very well defined yield stress compared to other materials. Yield stress is sometimes called yield strength.

A critical value of shear stress, below which a plastic or viscoplastic material behaves like a solid; above this value, a plastic material deforms and a viscoplastic material flows.