Engineering Materials – refers to the group of materials that are used in construction of manmade structure and
component. Its primary function is to withstand applied loading without breaking and without exhibiting excessive
deflection.
Major Classification of engineering materials
o Metals – most commonly use engineering material
- mostly opaque, hard, heavy, ductile, lustre, though and shiny
- they are solid with the except of mercury (Hg). They are shiny, ductile and malleable
- metal alloys are especially common it is obtain by mixing or melting two or more metals in order
to improve the properties of materials
- good conductor of heat
- Ferrous and Non-Ferrous
Ferrous – all metallic materials having iron as their main constituent. Other materials like carbon,
manganese, phosphorous, sulphur etc. Exist in various proportions in small quantity. (Cast Iron,
Steel, Wrought Iron, Carbon Steel, Pig Iron and Alloy Steel)
Cast Iron – hard, relatively brittle alloy of iron and carbon that can be readily cast in a
mold and contains a higher proportion of carbon than steel
Wrought Iron – tough malleable form of iron suitable for forging or rolling rather than
casting, obtained by puddling pig iron while molten. It is nearly pure but contains some
slag in the form of filaments.
Pig Iron – crude iron as first obtained from a smelting furnace, in the form of oblong blocks
Steel – a hard strong, grey, or bluish-grey alloy of iron with carbon and usually other
elements used extensively as structural and fabricating material.
Carbon Steel – steel in which the main alloying elements is carbon, and whose properties
are chiefly dependent on the percentage of carbon present.
Alloy Steel – in general, it is a steel that is alloyed with a variety of elements in total
amounts between 10% and 50% by weight to improve its mechanical properties.
Non-Ferrous – metallic materials which do not contain iron as their main constituent.
o Polymers – commonly known as plastics, a synthetic material made from a wide range of organic polymers
such as polyethylene, PVC, nylon, etc., that can be molded into shape while soft and then set into a rigid
or slightly elastic form.
- they have molecules having chains of small units combined to form big network
- 3 Classification of Polymers: Thermoplastic, Thermosetting and Elastomers
Thermoplastics - denoting substances that become plastic on heating and harden on cooling, and
are able to repeat these process.
Thermosets – describes a polymer-based material that is insoluble and non-melting.
Elastomers – highly elastic polymer with mechanical characteristics similar to rubber. Commonly
used for seals, adhesive, hoses and flexible part.
o Rubber – a rough elastic polymeric substance made from the latex of a tropical plant or synthetically.
o Natural Rubber – an elastic material obtained from the latex sap of trees.
o Synthetic Rubber – is any artificial elastomers. They are polymers synthesizes from petroleum
byproducts.
o Wood – hard fibrous material that forms the main substance of the trunk or branches of a tree or shrub
used for fuel or timber.
o Asbestos – a heat resistant fibrous silicate mineral that can be a woven into fabrics, and is used in fire-
resistant and insulating materials such as brake linings.
o Ceramics – solid compounds that may consists of metallic or non-metallic elements. Have excellent
corrosion and wear resistance, high melting temp., high stiffness, low electrical and thermal conductivity
and they are brittle.
