The ability of a material to retain its deformed shape when the load causing deformation is removed is called:

The ability of a material to retain its deformed shape when the load causing deformation is removed is referred to as plasticity. This property indicates that once the material has been deformed beyond its elastic limit (the point at which it can return to its original shape), it will not return to its original configuration after the stress is relieved. Instead, the material remains in a new shape, evidencing that it has undergone permanent deformation.

Plasticity is a crucial characteristic for materials that are designed to be shaped or molded, such as metals in various fabrication processes where they are hammered or pressed into new forms. In practical applications, understanding plasticity helps engineers and designers predict how materials will behave under different stress conditions.

The other terms—ductility, hardness, and stiffness—represent different properties that do not specifically define the ability to retain a deformed shape after the removal of load. Ductility pertains to a material’s ability to undergo significant plastic deformation before rupture, hardness relates to a material's resistance to deformation or scratching, and stiffness indicates how much a material will deform under a given load. Understanding these distinctions is important for selecting the right material for specific applications in refrigeration and other engineering fields.