The ability of metal to permit a change in shape without fracturing is known as:

The correct answer is ductility, which refers specifically to the ability of a metal to deform under stress, allowing it to be stretched into a wire or to change shape without breaking. This property is particularly important in HVAC sheet metal applications, where materials often need to be bent or shaped during installation and fabrication.

Ductility is essential for creating fittings, ducts, and other components that require manipulation without fracturing. The metals used in HVAC systems, such as aluminum and galvanized steel, are often chosen for their ductility because this allows them to be worked easily and to withstand various forms of mechanical stress during their use.

While elasticity relates to a material's ability to return to its original shape after deformation, ductility focuses on permanent change in shape under load. The term shortness does not pertain to material properties within this context, and strength generally refers to a material's ability to withstand an applied load without failure, rather than its ability to be shaped. Understanding ductility is crucial for HVAC professionals who work with sheet metal, as it directly affects their ability to install and create effective and durable ductwork systems.