Yield Strength

The stress at which a material exhibits a specified limiting deviation from proportionality of stress and strain. The minimum stress at which the material will start to physically deform without further increase in load. The load per unit of original cross-sectional area at that stress level. An offset of 0.2 percent is used for many metals such as aluminum-base and magnesium-base alloys, while a 0.5 percent total elongation under load is frequently used for copper alloys. See Tensile Strength.