Metals

Metals are made from ores which are extracted from the earth.

There are two main groups of metals:

Ferrous Metals

Most ferrous metals contain a material called carbon. The carbon content ranges from 0.1% to 4%. The higher the carbon content, the harder the metal.

Most ferrous metals will rust and almost all ferrous metals can be picked up with a magnet.

Example of ferrous metal

Low Carbon Steel

Carbon content: 0.1% – 0.3% (Low carbon steel with 0.15% to 0.3% carbon is sometimes called mild steel.)

Properties: quite strong; most common type of steel used today; produced in many different forms including sheets, bars and tubes

Uses: nuts, bolts, rivets, food cans, car body panels, in construction industry

Medium Carbon Steel

Carbon content: 0.3% – 0.7%

Properties: tougher than low carbon steel; can be treated with heat to alter its hardness

Uses: nails, screws, metal chains, wire ropes, screwdriver blades, some engine parts and bicycle wheel rims

High Carbon Steel

Carbon content: 0.7% – 1.3% (sometimes called tool steel)

Properties: very hard, but brittle; can be treated by heat to alter its properties

Uses: files, chisels, hacksaw blades, drill bits, scribers, springs

Cast Iron

Carbon content: 2% – 4%

Properties: very hard but brittle; suitable for casting because the molten form can be poured at a relatively low temperature

Uses: car engine blocks, manhole covers, engineer’s vices, bodies of various hand tools such as smoothing planes

Non Ferrous Metals

Non-ferrous metals do not have iron in them. Therefore they do not rust and cannot be picked up by magnets.

Example of Non-Ferrous metals

Aluminium

Properties: second most widely used metal after steel; light, good conductor of electricity and heat; greyish-white; easy to cut and machine

Uses: display racks, cooking foil, drink cans, overhead power cables, casings and panels for electrical goods, road signs

Copper

Properties: reddish-brown; ductile, malleable; can be cut sawn, filed and machined easily; excellent conductor of heat and electricity

Uses: electrical fitting and wires, printed circuit boards, tips of soldering iron, domestic water pipes, cylinders, cooking utensils, decorative ornaments

Tin

Properties: silvery-white, non-toxic, soft; normally used by plating it onto other metals such as mild steel (tinplate)

Uses: food cans, plating on copper tracks of printed circuit boards

Zinc

Properties: silvery-blue, does not corrode easily, ductile, not very strong

Uses: manufacture of other metals such as brass and galvanised iron, batteries, rust-proof paints

Lead

Properties: very heavy, but soft; appears bright and shiny bluish-grey when cut but surface changes quickly to a dull grey; toxic, resistant to corrosion and many chemicals

Uses: can be mixed with other materials to make them easier to machine; acts as a protection against x-rays and radiation, core of some batteries

Duralumin

Properties: greyish-white; made by mixing aluminium with copper and manganese; hard and tough

Uses: used in the transport industries for making body panels and machine parts, portable ladders, door and window frames

Brass

Properties: good conductor of heat and electricity, golden yellow alloy, easy to machine and solder, made by mixing copper and zinc

Uses: pins of electrical plugs, nuts, bolts, screws, hinges, some machine parts, musical instruments, decorative artifacts, locks, keys

Bronze

Properties: made by mixing copper and tin; reddish-yellow, hard-wearing, corrosion resistant, easily machined

Uses: ship propellers, bells, gears, bearings, statues

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