What property of a material allows it to undergo considerable plastic deformation under tensile load before actual rupture?

The property of a material that allows it to undergo considerable plastic deformation under tensile load before actual rupture is ductility. Ductility refers to the ability of a material to stretch and deform when subjected to tensile forces, enabling it to absorb energy and undergo significant deformation without fracturing. This characteristic is vital in many engineering applications where materials need to withstand stress and strain without failing suddenly.

Ductile materials can be drawn into wires or molded into various shapes, making them valuable in construction, manufacturing, and various mechanical applications. Metals such as copper and aluminum are prime examples of ductile materials, as they can be elongated considerably while still maintaining their structural integrity during the process.

In contrast, brittleness is characterized by a tendency to fracture without significant deformation, which does not support plastic deformation. Elasticity describes a material's ability to return to its original shape after the removal of a load, while stiffness refers to how rigid a material is, which does not directly correlate with the ability to deform plastically. Thus, ductility is the key property in this context.