duktilitet

Duktilitet, or ductility in English, is a material's ability to undergo substantial plastic deformation before fracture. It is commonly exemplified by drawing a metal into wire or bending without cracking. Ductility is distinct from malleability, which describes deformation under compressive loads, such as hammering into sheets. In practice, ductility is most often quantified by tensile tests.

In a tensile test, ductility is reported as the percent elongation and as the reduction of area at fracture. Elongation measures how much length the specimen gains before breaking, while reduction of area reflects how the cross‑section shrinks at failure. True plastic strain and necking behavior provide additional insight. Metals with high ductility typically exhibit necking and a long, continuous plastic region before rupture.

Several factors influence ductility. Crystal structure plays a major role; face-centered cubic metals (for example, copper and aluminum) usually show high ductility, while some body-centered cubic metals are less ductile at room temperature. Temperature, strain rate, grain size, and impurities also affect ductility; ductility generally increases with temperature and can decrease with fast deformation or large impurity content. A ductile-to-brittle transition may occur in some materials at low temperatures or certain compositions.

Applications rely on ductility for forming and shaping workpieces, such as drawing wires, deep drawing of shells, and shaping components without cracking. Ductile materials tend to fail after significant plastic deformation, showing necking, whereas brittle materials fail with little deformation.

Etymology: duktilitet derives from Latin ducere, “to lead.”