Materials Performance: Plasticity

Understanding Plasticity

Plasticity points to a material’s ability to undergo permanent deformation without breaking or cracking when a force is applied.
It’s a fundamental mechanical property in metals particularly, which allows for processes such as bending, shaping, and extrusion.
Unlike elasticity, when the force is removed from a plastic deformation, the material doesn’t return to its original shape.

Ductility: This term is an aspect of plasticity and signifies a material’s ability to deform under tension. In other words, ductile substances can stretch without breaking, such as gold or copper.
Malleability: Also a facet of plasticity, this describes how a material deforms under compression. Malleable materials like lead or aluminium can be compressed or moulded without breaking.
Yield Point: The yield point of a material is the stress level at which it begins to deform plastically. After the yield point, the material does not return to its original shape once the force is removed.
Work Hardening: This occurs when a material becomes stronger and harder due to plastic deformation. The deformation introduces defects into the crystal structure of the material, preventing further deformation and thus making the material sturdier.

Metals like copper, aluminium, and gold exhibit high levels of plasticity, making them useful in numerous applications from electrical wiring to jewellery.
Polymers are also characteristically plastic, capable of being moulded into a wide array of shapes for consumer products. Some common examples include PVC and silicone.
Clay and similar ceramics can be moulded when wet, displaying plasticity, and then hardened to retain the shape.

Understanding plasticity is crucial in manufacturing processes such as metalworking, where materials must undergo significant deformation without breaking.
Ductile materials, thanks to their stretching ability, are preferred in crafting wires or threads. Malleable substances find their usage in making plates, disks or hardware components.
Architecture and construction industries use materials with high plasticity for the design of structures that need to withstand variable and significant loads without fracturing.