Properties Of Metals
Properties of Metals
The various properties of metals can be assessed by accurate laboratory tests on sample pieces. The following are the terminologies that are associated with these properties.
- Brittleness: It is the tendency of the metal to shatter without significant deformation. It will shatter under a sudden low stress, but will resist a slowly-applied, higher load.
- Conductivity: It is the ability of a metal to conduct heat and electricity. Silver and copper are excellent thermal and electrical conductors.
- Ductility: It is the property of being able to be permanently extended by a tensile force. It is measured during a tensile or stretching test, when the amount of stretch (elongation) for a given applied load, provides an indication of a metal’s ductility.
- Elasticity: It is the ability of a metal to return to its original shape and size after the removal of any distorting force. The ‘Elastic Limit’ is the greatest force that can be applied without permanent distortion.
- Hardness: It is the ability of a metal to resist wear and penetration and is measured by pressing a hardened steel ball or diamond point into the metal’s surface. The diameter or depth of the resulting indentation provides an indication of the metal’s hardness.
- Malleability: It is the ease with which the metal can be forged, rolled and extruded without fracture. Stresses induced into the metal, by the forming processes, have to be subsequently relieved by heat-treatment. Hot metal is more malleable than cool metal.
- Plasticity: It is the ability to retain a deformation after the load producing it has been removed. In fact, plasticity is the opposite of elasticity.
- Tenacity: It is the property of a metal to resist deformation when subjected to a tensile load. It is proportional to the maximum stress required to cause the metal to fracture.
- Toughness: It is the ability of a metal to resist suddenly applied loads. A metal’s toughness is tested by impact with a swinging pendulum of known mass.
- Strength: There are several different measurements of the strength of a metal, as may be seen from the following sub-paragraphs.
- Tensile Strength: It is the ability to resist tension forces applied to the metal.
- Yield Strength: It is the ability to resist deformation. After the metal yields, it is said to have passed its yield point.
- Shear Strength: It is the ability to resist side-cutting loads, such as those imposed on the shank of a rivet, when the materials it is joining attempt to move apart in a direction normal to the longitudinal axis of the rivet.
- Bearing Strength: It is the ability of a metal to withstand a crushing force.