MECHANICAL PROPERTIES OF METALS
The various properties of metals may be assessed, by accurate laboratory tests on sample pieces. The terminology, associated with these properties, is outlined in the following paragraphs.
Brittleness
The tendency of the metal to shatter, without significant or momentous deformation. It will shatter under a sudden, low stress or force but will resist a slowly-applied, higher load.
Conductivity
The ability of a metal or alloy to conduct heat, (thermal conductivity) and electricity. Silver and copper are excellent(good) thermal and electrical conductors
Ductility
The property of being able to be permanently extended or enlarged by a tensile force. It is measured during a tensile, or stretching, test, when the amount of stretch, for a given applied load, provides an indication of a metal’s ductility.
Elasticity
The ability of a metal or alloy 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(long-lasting) distortion.
Hardness
The ability of a metal or alloy to resist wear and penetration. It is measured by pressing a hardened steel ball or diamond point into the metal’s surface(body). The diameter or depth of the resulting indentation provides an indication of the metal’s hardness.
Malleability
The ease, with which the metal or alloy can be forged, rolled and extruded without fracture. Stresses, induced into the metal, by the forming processes(system), have to be subsequently relieved by heat-treatment. Hot metal is more malleable than cool metal.
Plasticity
The ability to retain a deformation after the load producing it has been eliminated or removed. Plasticity is, in fact, the opposite of elasticity.
Tenacity
The property of a metal or alloy to resist deformation when subjected to a tensile load. It is proportional to the maximum (peak) stress required to cause the metal to fracture.
Toughness
The ability of a metal or alloy 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 or alloy, as may be seen from the following sub-paragraphs
Tensile Strength
The ability to resist tension forces applied to the metal or alloy
Yield Strength
The ability to resist deformation. After the metal or alloy yields, it is said to have passed its yield point.
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