Resilience: Resilience is the ability of a metal to absorb energy and resist soft and impact load.

Toughness: When a huge external force is applied on a metal, the metal will experience fracture. Toughness is the ability of a metal to resist fracture. The ability of a material to resist fracture due to high impact loads, is called toughness.

Stiffness: When an external force is applied on a metal, it develops an internal resistance. The internal resistance developed per unit area is called stress. Stiffness is the ability of a metal to resist deformation under stress.

Hardness: Hardness is the ability of a metal to resist permanent change of shape caused by an external force.

The process extensively used for making bolts and nuts is cold heading.