Materials Performance: Ductility

Understanding Ductility

Ductility in materials is the measure of a material’s ability to deform and elongate under stress without breaking.
It’s often characterised by the material’s ability to be stretched into a wire or drawn into a thin sheet.
It generally increases with heat and decreases as the material is made colder.

Plastic deformation: In ductile materials, plastic deformation refers to the irreversible deformation that occurs after the elastic limit is passed.
Necking: It is the stage in ductility where the cross-sectional area of the material reduces significantly when stress is applied, typically before a ductile material fractures.
Work hardening or strain hardening is the process of strengthening a metal through plastic deformation.

Metals like copper, gold, silver and steel are generally considered highly ductile materials due to their ability to be drawn out into fine wires.
Plastics, such as polyethylene and polyvinyl chloride, can also display good ductility.

Temperature: An increase in material temperature generally increase ductility.
Impurities: The presence of impurities can reduce a material’s ductility.
Grain size: Fined grained materials tend to be more ductile.

Ductility is important in the manufacturing process of materials. Ductile materials can be bent, rolled or shaped without breaking, making them ideal for a variety of applications such as wires, sheet metals and structural frames.
It is also essential for materials involved in structures designed to withstand earthquakes or shocks, as these materials can absorb energy and deform without breaking.
Designers also choose ductile materials when creating products that need to endure significant deformations without breaking, such as car bodies and crash barriers.