Hardness is a very important property of the metals and has a wide variety of meanings. It embraces many different properties such as resistance to wear, scratching, deformation and machinability etc. It also means the ability of the metal to cut another metal.
The hardness is usually expressed in numbers which are dependent on the method of making the test.
Malleability:
Malleability is the property by which a metal can be rolled into thin sheets. Highly malleable metals (like Mild Steel) are extensively used in making sheet metals.
Lead is a soft, malleable, ductile, bluish-white, dense metallic element, extracted chiefly from galena and found in ore with zinc, silver and copper. Whilst it is still used for its malleability and corrosion resistance, it is its chemical properties that make it a thoroughly modern metal.
Resilience:
Resilience is the ability of a metal to absorb energy and resist soft and impact load.
Creep:
When a metal is subjected to a constant load (below its yield point), at high temperature, for a prolonged period of time, it undergoes a permanent deformation. This tendency of the metal is called creep.
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.
Ductility:
Ductility is the property by which a metal can be drawn into thin wires. It is determined by percentage elongation and percentage reduction in area of a metal.
Malleability:
Malleability is the property by which a metal can be rolled into thin sheets. Highly malleable metals (like Mild Steel) are extensively used in making sheet metals.
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.