Engineering Materials

• Cast iron properties:

  • Good compressive strength.
  • Hard, difficult to machine.
  • Suitable for casting.
  • Rusts easily.
  • Relatively low cost.
• Low Carbon Steel Properties:

  • Lower strength than other steels.
  • Tough.
  • Relatively low cost.
• High carbon steel properties:

  • Strong and hard.
  • Not as tough as low carbon steel.
  • Difficult to form.
• Properties of stainless steel:

  • Strong and hard.
  • Difficult to machine.
  • Good corrosion resistance.
  • Relatively expensive.
• Properties of Aluminium and its alloys:

  • Light, soft, ductile, malleable.
  • Good conductors.
  • Corrosion resistant.

  Used for Aircraft bodies, cans etc.
• Properties of Copper:

  • Malleable, ductile, tough.
  • Good conductor.
  • Easily joined.
  • Corrosion resistant.

  Used in electrical circuits, hot water tanks etc.
• Properties of Brass (copper and zinc):

  • Corrosion resistant.
  • Good conductor.
  • Easily joined.
  • Casts well.

  Used for ornaments, boat fittings etc.
• Properties of Bronze:

  • Tough and hardwearing.
  • Corrosion resistant.

  Used in: Coins and bearings.
• Properties of lead:

  • Soft and malleable.
  • Corrosion resistant.
  • Low melting point.
  • Easy to work.

  Used in radiation protection and roof covers.
• Properties of zinc:

  • Poor strength to weight ratio.
  • Low melting point.
  • Corrosion resistant.
  • Easily worked.

  Used in: Coating (galvanising) steel.
• Cold working is when a metal is not heated before work is done to it.

  Causes grains in the metal to stretch out.
• Annealing is a heat treatment that makes a metal softer and easier to work by increasing the grain size of the metal.
• Normalising is making metals tough with some ductility.
• Quenching is the rapid cooling of a hot metal by immersing it in a liquid, often oil or brine.
• Tempering is where some of the brittleness is removed at the cost of some hardness.
• Hardening increases the hardness and strength of a metal due to a change in atomic arrangement.
• Carburising is the addition of carbon to the surface of a low-carbon steel to improve hardness and strength.
• Corrosion is where the surface of a material reacts with its environment.
• ABS is strong and rigid, twice the cost of polystyrene but harder and tougher than polystyrene.
• Factors influencing design of solutions:

  • Engineered lifespan.
  • Maintenance requirements.
  • Availability of materials and user requirements.