Marine Engineering

PROPERTIES

Elasticity
The elasticity of a metal is its power of returning to its original shape after deformation by force. Many materials behave to some extent like powerful elastic, and within limits, will recover their shape when the load on them is removed.

Hardness

The hardness of a metal is a measure of its ability to withstand scratching wear and abrasion, indentation by harder bodies, marking, by a file etc.
The Brinnel hardness of a metal is found by pressing a ball on to the surface of the metal, the hardness number being found by dividing the load on the ball by the surface area of the impression.

Malleability

This is the property of permanently extending in all directions without rupture by pressing, hammering, rolling, etc. It requires that the metal shall be plastic but is not so dependent on strength e.g. lead is malleable.

Plasticity

This is a rather similar property to malleability and involves permanent deformation without rupture.It is the extreme opposite to elasticity.

Strength

The strength of a metal is its ability to resist the application of force without rupture.In service a material may have to withstand tension,compression,or shear forces.The strength of material is measured by loading it in a testing machine until fracture.

Toughness

Is the amount of energy a material can absorb before it fractures or measure of toughness of a metal may be obtained by nicking it, placing it in a vice and striking it hard with a hammer