PROPERTIES OF MATERIALS

The choice of a material for use as an engineering component depends upon the conditions under which it will be employed.

DIAGRAM SHOWING EFFECT UPON MECHANICAL PROPERTIES BY INCREASE IN CARBON CONTENT

Conditions could be simple or complex and hence in choosing the engineer requires some guidance. This guidance is invariably in the form of a materials mechanical properties and those of principal interest are as follows

Ductility: Is that properties of a material which enables it to be drawn easily into wire form. The percentage elongation and contraction of area, as determined from a tensile test are a good practical measure of ductility.

Brittleness: Could therefore be defined as lack of ductility.

MALLEABILITY: Is a property similar to ductility. If a material can be easily beaten or rolled into plate form it is said to mealleable.

ELASTICITY: If all the strain in a stressed material disappears upon removal of the stress the material is elastic.

PLASTICITY: If none of the strain in a stressed material disappears upon removal of the stress the material is plastic.

HARDNESS: A meterials resistance to erosion or wear will indicate the hardness of the material.

STRENGTH: The greater the load which can be carried the stronger the material.

TOUGHNESS: A materials ability to sustain variable load conditions without failure is a measure of a materials toughness or tenacity. Materials could be strong and yet brittle but a material which is tough has strength and resilience.