yeldstrengths

Yield strengths refer to the stress levels at which a material begins to deform plastically, meaning some permanent deformation will remain after the load is removed. In the elastic portion of a stress–strain curve, deformation is reversible, but beyond the yield strength the material yields and cannot return to its original shape.

Because many materials do not have a sharp yield point, engineers often use the 0.2 percent offset method to define a practical yield strength. This convention identifies the stress corresponding to a strain of 0.2% offset from the elastic region as the yield strength. Some materials exhibit a distinct upper or lower yield point, where yielding starts at a specific stress, followed by a drop or plateau before work hardening continues.

Yield strength is influenced by composition, microstructure, and processing. Grain size, phase distribution, and precipitates can strengthen or weaken a material via mechanisms such as grain-boundary strengthening and precipitation hardening. Temperature and strain rate also affect yield strength; higher temperatures generally reduce it, while faster loading can increase it in some metals.

In design, yield strength is a key parameter for determining allowable stresses and factors of safety. It is distinct from tensile strength (ultimate or fracture strength) and from ductility measures such as elongation. Materials with high yield strengths are sought for load-bearing applications, while low yield strength materials may offer greater formability.

Common examples include metals like steels, aluminum alloys, and titanium alloys, each with characteristic yield strengths that guide material selection for structural, automotive, and aerospace components.