Knowledge about the properties of materials is often tested
in the written paper. You are expected to know about
paper/card and at least one other material group.
General properties of metals
• Heat conductivity
• Electrical conductivity
• Density (Weight)
• High melting points
Sources of metals
• Gold is the only metal that is found in a useable form.
• All others are found as ores.
• 25% of the Earth’s crust is made up of metal ores.
• The most abundant ores are aluminium and iron
This group of metals contain metals
• Iron is produced in a blast furnace.
• The material that is produced is called pig iron.
• This is converted into steel by adding carbon to its structure
in an oxygen furnace or an electric arc furnace.
• Iron is soft and ductile, not particularly useful.
• When carbon is added, it becomes steel and its properties
• Medium and high carbon steel can be heat treated to make
them even stronger so that they can be formed into cutting
BASE ADDITIONAL TYPE OF
DUCTILITY HARDNESS TOUGHNESS
MATERIAL CARBON STEEL
3.5% CAST IRON BRITTLE
NAME COMMON USES
Nuts, bolts, washers, car bodies, panels
Mild Steel for cookers, appliances etc.
Springs, general gardening tools
Hand tools, scribers, dot punches,
High carbon steel
chisels, plane blades.
Cast iron Machine parts, brake discs, engines
• Do not contain iron
• Although aluminium ore is the most common on Earth, it is
not the most processed metal, steel is.
• This is because aluminium production uses large amounts
of energy and energy = cost.
METAL COMMON USES AND PROPERTIES
Aluminium Kitchenware, power cables, drinks cans, aircraft bodies.
Copper Electrical contacts, electrical cable and wire, jewellery.
Gold Jewellery, electrical contacts (does not oxidise)
Lead Soft but heavy metal, used on roofs, durable
Platinum Precious metal used in jewellery, but also to make wires
Silver Cutlery, decorative items, jewellery.
Tin Used to coat steel plate in food cans
Surgical applications (very clean) such as hip
Used for coating steel (galvanising), can be die-cast to
produce high detail products.
• Two (or more) metals are combined to produce
materials with enhanced properties.
• Example: adding zinc to copper produces a much
harder and stronger material than pure copper.
• Benefits can be changes to: colour, strength,
hardness, ductility, resistance to corrosion/oxidation,
electrical/thermal properties, flow properties...
NAME BASE METAL COMPOSITION COMMON USES
4% copper Structural
DURALUMIN Aluminium 1% manganese components for
0.1% magnesium aircraft
Cast valves and
BRASS Copper 35% zinc taps, boat fittings.
BRONZE Copper 10% tin
• Most metals, including steel, will become less hard and
more ductile when heated.
• By alloying with other metals, high speed steels can be
produced that keep their cutting edge even when they are
cutting at high temperatures.
ALLOY STEEL ALLOYED WITH CHARACTERISTICS COMMON USES
Tough and wear-
Stainless steel resistant; corrosion Sinks, cutlery etc.
Tungsten, chromium, Very hard, will cut Cutting tools, such as
High Speed Steel
vanadium while at red heat drills
Fine press tools,
Very hard and tough,
Chromium, extruder dies,
Tool and die-steels excellent wear
manganese blanking punches
High tensile steels Nickel strength; corrosion
Work hardening & heat treatment
• Because metal is made up of crystals, the way they are
arranged affects the properties (strength) of the metal.
• There are two categories of hardening, cold-working
(bending, rolling, hammering, drawing) and heat treating.
• Heat treatments are process that heat and cool metals in
a controlled way in order to improve their properties.
Some common heat treatments are:
Other types of hardening
• Mild steels do not contain enough carbon to be affected
by heat treatments.
• These can be case hardened; i.e. the outer surface is
hardened, while the centre remains tough and shock
• Types of case hardening are: carburising and nitriding.
There are many ways of processing metals to manufacture
These can be divided into three categories:
• These are processes where material is cut away.
• Sawing and filing
• Drilling and milling
• Grinding and sanding
• Blanking and piercing
• These are processes where materials are joined
• Bolts and screws
• Welding, brazing and soldering
• These are processes where materials are reshaped
without loss of material. There are further categories:
• Like polymers, metals can be heated to known melting
• When they become liquid, they can be poured into moulds
made of sand, alloy steel, or ceramics.
• Three main types of casting are sand casting, die-casting
and investment casting