Ductiliteetti

Ductiliteetti, or ductility in materials science, is the ability of a solid to undergo significant plastic deformation before fracture under tensile loading. It is commonly quantified by measurements taken in a tensile test, such as elongation at fracture and reduction of area. Materials with high ductility can be drawn into wires or formed into complex shapes without breaking, while brittle materials fracture with little or no plastic deformation.

The underlying mechanism lies in the mobility of dislocations within a material’s crystal lattice. In metals, sufficient dislocation glide allows permanent deformation without immediate failure. Ductility is influenced by temperature, grain size, composition, and the presence of second-phase particles. Generally, larger grains and certain alloying elements can enhance ductility, while very fine grains may increase strength at the expense of some ductility. Ceramics and glasses typically exhibit low ductility at room temperature.

Measurement and interpretation: A standard tensile test provides percent elongation and reduction of area to quantify ductility. True stress–strain analysis can offer additional insight at large strains. Ductility is related to toughness but is not identical; toughness combines strength, ductility, and energy absorption before fracture.

Applications: Ductility is crucial for forming operations such as drawing, extrusion, and bending. Alloys are designed to balance strength and ductility for specific uses. The term malleability is related but refers more to deformation under compressive forces, not to tensile ductility. Examples of ductile materials include gold, copper, and many steels, whose deformation capacity enables reliable shaping and forming.