Ductilitás

Ductilitás, or ductility, is the ability of a material to undergo plastic deformation before fracture. It is most often assessed in a tensile test, using measures such as percent elongation at fracture and percent reduction of area. A ductile material can deform significantly, often forming a neck and sustaining large strains, which helps absorb energy and provides warning before failure. By contrast, brittle materials fracture with little plastic deformation and generally absorb less energy.

Ductility depends on temperature, strain rate, and the material's microstructure. Metals typically show notable ductility, with copper and aluminum as classic examples, while many ceramics are inherently brittle. Polymers can be highly ductile, depending on their composition and temperature. The mechanism behind ductility involves the mobility of dislocations and other deformation processes; higher dislocation mobility and processes like cross-slip increase ductility. Elevating temperature generally enhances ductility (hot working), whereas lowering temperature can reduce it and, for some steels, induce a ductile-to-brittle transition.

Ductility is related to but distinct from malleability, which describes deformation under compressive loading to form sheets or shapes. In engineering, ductility is valued for forming processes such as drawing and extrusion, and for toughness, or the ability to absorb energy without sudden failure. Materials selection often balances ductility with strength and hardness to meet structural and functional requirements.