The elasticity of a metal refers to the rate at which a given metal sample is able to distort its size and shape under a range of stress and strain forces and other externally varying factors. Elasticity can also refer to the measured degree of ductility of a metal.
Metals that continually undergo force applications to expand elastically are more prone to cracking and crevice, intergranular and stress corrosion due to the greater surface area that is exposed when elongated.
The elastic deformation of a metal is a reversible occurrence where the metal can return to its original state. Metals that are deformed past the point where a return to their original state is impossible are referred to as being plastically deformed and not elastic. When stress or strain (tension or compression) is applied to a metal, a series of forces act on the metal forcing it to expand in an axial or radial formation - essentially elongating itself. If the applied stress or strain is within the force load allowances for the given metal based on its modulus of elasticity then the metal is said to be elastic and it will return to its original form when the forces are removed. If the applied stress or strain is greater that the modulus of elasticity determined range then the metal will be permanently deformed.