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Metals
An overview
13TH OCTOBER 2009
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Bibliography
Fawcett, Ian (2009), Aqa Design and technology: Resistant Materials technology gcse, nelson
thomas
Evans, B (2008), aqa design & Technology: product design as/a2, nelson thomas
willacy, D (1986), craft and design in metal, hutchinson
hicks, g a (1980), design and technology metal, wheaton
chapman, c (1998), working with materials, collins
bedford, j (2000), metalcraft theory and practice, john murray
data.org.uk
(http://www.data.org.uk/index.php?option=com_content&view=article&id=498&Itemid=453)
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aim
to provide an overview of common metals and their:history TIMELINE
extraction, ORE FURNACING AND trading
properties (physical and mechanical) and types
common uses in industry, domestic, commercial, fashion
work hardening, heat treatments
joining and other processes used in the workshop
recycling
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HISTORY TIMELINE
7700 - 3300 BC
COPPER AGE
3200 - 1200 BC
BRONZE AGE
1200 - 332 BC
IRON AGE - Iron Pillar of Delhi, with high levels of phosphorus results in reduced corrosion.
300 BC
Basic Steels - WOOTZ STEEL from India, BULAY STEEL from Russia, NORIC STEEL widely used in europe,
mainly by the Romans.
25 BC - 140 AD
New mining techniques from the Romans using Hydraulics.
1400 AD
Smelting to higher standards with now purer ores.
1709 AD
More efficient smelting due to hotter furnaces using coke as opposed to coal as the fuel, producing Wrought
Iron. With this the demand increased with it being used in the production of steam engines, rails, and structures.
1761 AD
Aluminium in its impure form is discovered.
1803 AD
The Gold rush in the United States.
1855 AD
Crown Jewels.
Aluminium in its pure form is discovered, and is worth more then gold. Bars are on exhibition with the French
1890 AD
stainless steel.
Aluminothermirc Steel, a process taking the metal to high temperature and mixing in aluminium. Similar to
1915 AD
Stainless Steel as we know it today.
1980 AD
Modern Metals, and uses - Using metals in a new ways with the assistance of modern technology. These include
SMA’s (Shape Memory Alloys) developed by NASA,
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EXTRACTION
The primary method used for extracting metal ore from the ground is via mining:
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Open-pit mining: This is used for large amounts of ore. Soil and rock
are moved from the surface to reveal the ore, forming a large open
pit, spanning up to 900 meters across
•
Opencast mining: Is method is similar to open-pit mining, but is
done mainly near the surface not requiring deep excavation with
only the surface being removed
•
Shaft mining: A tunnel is dug either into a mountain or down deep
into the ground. From the shaft tunnels are dug, and the ore is
drilled or blasted away in chunks, taken to the surface by either
conveyor belts or by hoists and pulley systems.
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MINE TO METAL
From ‘mine to metal’, this is the process that the Ore goes through to produce
Steel.
1.Iron Ore is
extracted
from Mine
2. Ore is crushed,
separated from
surrounding materials
by high powered
electromagnetic
5. Further heat
treatment takes place
before metal is
‘soaked’ and then
placed into forging mill
or ‘casting’
3. Iron Ore is poured
with coke and
limestone into the
blast furnace - melting
it to ‘Molten Iron’
4. Molten Iron is sent
to the ‘Mixer’ to obtain
best result and
balance in the metal
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TRADING
Ores (metals) are traded internationally and comprise a sizable portion of
international trade in raw materials both in value and volume. This is due to
the worldwide distribution of ores being unequal and dislocated from
locations of peak demand and from smelting infrastructure.
Most base metals (copper, lead, zinc, nickel) are traded internationally on
the London Metal Exchange, with smaller stockpiles and metals exchanges
monitored by the COMEX and NYMEX exchanges in the United States and
the Shanghai Futures Exchange in China.
Various benchmark prices are set yearly between the major mining
conglomerates and the major consumers, and this sets the stage for smaller
participants.
Native ores are found all over the world with the key global producers being
former USSR, China and Australia. A wider list can be found in the
Appendices
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Metal properties (1)
METALS ARE DESCRIBED BY THEIR PHYSICAL, MECHANICAL AND
CHEMICAL PROPERTIES.......
Physical properties:
Appearance
*Aesthetics – Today the decision to buy a product is often based on the appearance
rather than its technology as so many products have similar functional
characteristics.
Colour – helps to identify the type of metal. E.g differentiating between yellow metals such
as gold, gilding metals and brass
Chemical resistant
Corrosion resistant
Optical properties – how easily light passes through it
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metal properties (2)
further physical properties:
Density – Most metals have a high density. This means an object made of metal has a
higher mass than the same object made in another material.
Conductivity – the ease of which heat or electricity travels through the material. The best
conductors are silver, copper and aluminium which is why these metals are used for cooking
pans and electricity cables
Insulation
Fusibility- the ease with which a metal melts. All metals have a different melting point.
* Tungsten has the highest melting point of any metal at 3410◦C and is therefore
used as the filament in lightbulbs
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metal properties (3)
mechanical properties:
Toughness – allows a metal to be bent or twisted and to resist impact without breaking
Brittleness – means the metal will break without bending. This is a dangerous and
undesirable property
Ductility – metals which can be stretched whilst cold, without breaking. Copper, Aluminium
and Platinum have this qualities which is why they are used for making wire
Durability – has a long useable life
Plasticity - the ability to permanently change its shape
Hardness – the surfaces ability to resist wear, scratching and indentation. Tested using a
diamond point, they are given a number to describe the level of hardness
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metal properties
Further mechanical properties:
Elasticity – the ability of a metal to return to its original size or shape
Magnetism – a property found in the majority of ferrous metals such as Iron and Steel
Malleability – metals which can withstand being bent, hammered and rolled out without
breaking. Gold and aluminium can be rolled until they are paper thin
* A stack of 10,000 gold leaves is only 1mm thick!
Tenacity – tensile strength. How strong the metal is when resisting a direct pull. Many
metals withstand strain as the small particles that make up metals stay close together
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metal types
METALS
NON FERROUS
FERROUS
PURE
METALS
METALS ARE DIVIDED INTO 3
BASIC CATEGORIES:
(1)FERROUS, (2)NON
FERROUS, (3) ALLOYS
PURE
METALS
ALLOYS
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ALLOYS
metal types - key features
Ferrous Metals
contain Iron
Are almost all magnetic
pure metals
Unless treated, corrode very easily
Consist of one single element, they have only one type of
atom in it.Pure metals are rarely used as alone, they do not
have the desired working properties. These are obtained by
Non-Ferrous metals
Metal Alloys
alloying metals.
Most alloying is done
by mixing the ingredients of the alloy in their liquid
stateSuccess depends on the property of fusibility.
contain no Iron
Stronger and lasts longer than either pure metal
Not magnetic
Example: Pure gold is shiny and expensive, copper is duller,
less expensive but much harder. Combining the two metals
creates a metal usable for coins and jewellery
More resistant to corrosion
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non-ferrous metals: properties
PURE METALS ARE OFTEN TOO SOFT TO BE OF PRACTICAL USE, WHICH IS WHY MUCH
OF METALLURGY FOCUSES ON THE FORMULATION OF USEFUL ALLOYS.
Metal
Physical Properties Mechanical Properties
Aluminium
Corrosion resistant, good conductor
of heat and electricity, good
fusibility
high strength, lightweight,
malleable, ductile, difficult to join,
polishes well
Copper
Good conductor of heat and
electricity
Malleable, ductile, easily joined,
polishes well, expensive
Zinc
Corrosion resistant, Fair conductor
of electricity
Ductile and easily worked between
100C-150C, Otherwise Hard and
Brittle,
Gold
Good resistance to oxidation and
an excellent conductor of electricity
Gold is dense, soft, shiny and the
most malleable and ductile pure
metal known.
Lead
High resistance to atmospheric
conditions, poor electrical
conductivity
Very soft, Highly malleable, Dense,
Ductile, When alloyed with tin
makes soft solder
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Non-Ferrous metals: common uses
Aluminium
Copper
Gold
Lead
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metal alloyS: properties
ALLOYING INCREASES STRENGTH, HARDNESS AND DUCTILITY, ENHANCES RESISTANCE
TO CORROSION AND OXIDISATION, CHANGES MELTING POINT, COLOUR AND
ELECTRICAL/THERMAL PROPERTIES
Alloy
Duralu
min
Brass
Bronze
Nitinol
Base Composite Physical
Metal
s
Properties
Aluminium
Copper
With Titanium keeps
4% Copper
the strength when hot,
1% Manganese
Magnesium makes
0.1% Magnesium
metal harder
35% Zinc
1%-2% Lead/Tin
Copper
10% Tin
Nickel
50%Nickel
50% Titanium
Mechanical
Properties
Harder than normal Aluminium
Hardens with age
Tin produces
Works well when hot, Malleable,
increased resistance Ductile, Polishes well and Solders
to corrosion
easily
Tough, resists corrosion, casts
well, malleable, solders and
brazes easily
Physiological and
chemical compatibility
with the human body
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Smart Metal Alloys (SMAs) with
Shape Memory and Superelasticity
Metal alloys: common uses
Duralumin
brass
bronze
nitinol
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ferrous metals: Properties
IRON IS PRODUCED DIRECTLY FROM ITS ORE THROUGH THE USE OF A BLAST
FURNACE, PRODUCING PIG IRON. PIG IRON IS CONVERTED INTO STEEL BY
INTRODUCING carbon into it’s structure
Metal
Mild Steel
Medium
Carbon Steel
High Carbon
Steel
Cast Iron
Physical Properties
Mechanical
Properties
Poor resistance to corrosion
Tough, Ductile, Malleable
Good Tensile Strength
Easily joined (Welding or Brazing)
Better resistance to corrosion
Tougher, harder but less ductile
Good resistance to corrosion
Very tough,Very hard, Malleable
Can be hardened and tempered, even
less ductile
Excellent resistance to deformation,
and wear resistance
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Brittle, low melting point, good fluidity,
castability, excellent machinability,
Ferrous metals: common uses
Mild Steel
Medium Carbon Steel
High carbon Steel
Cast Iron
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work hardening
work hardening is a name given to the effects of processing
i.e. rolling, bending or hammering a metal while it is cold
in order to return the metal to its original ‘soft’ state the metal
must be annealed
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heat-treating metals
THE PROCESS OF HEATING & COOLING METALS TO CHANGE
THE PROPERTIES OF THE MATERIAL
Annealing - heat to a certain temperature is introduced to mobilise the atoms and relieve internal stresses
making the material softer and more ductile
hardening - this changes the structure of carbon within steel when heated to a specific temperature. when
immediately ‘quenched’ it causes internal stresses which harden and strengthen the material
quenching - this is the term given to the rapid cooling of metal following heat treatment.
tempering - carried out after hardening of medium and high carbon steels to remove any brittleness. the
hardened material is cleaned to its natural shiny grey colour. heat is then applied and rapidly ‘cooled’ when
the correct tempering colour is seen
normalising - process is confined to steel. specific heat temperature is applied and maintained (‘soaked’)
for a short period and then allowed to cool in air to produce greater toughness and ductility
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in the workshop - joining metals
Soldering – This requires the least temperature to form a
metallic joint. This process is used predominantly in joining
electronic components to circuit boards. The solder is primarily
tin.
Brazing – This requires a higher temperature. The filler rod is a
brass alloy called a brazing spelter. The materials that can be
treated in this way include Copper and Mild Steel.
Welding – process involving intense heat in order to adhere 2
metal items. The metals are heated with an additional filler
added to which forms a molten pool which then cools to
become a strong joint. Welding differs from soldering and
brazing in that the materials being joined must be the same as
the filler material
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in the workshop - other processes
Bending – Bending of sheet metal can be done in several ways. Folding
bars are one common method although many schools have bending
machines.
Riveting – Is a method of joining materials which can be done either using
hand tools or by machine
Cutting - either by hand or machine. Equipment includes, hack saws, band
saws, jigsaws
Drilling – either by hand or machine using specialised drill bits. Equipment
includes power drills, hand drills, pedestal drills also known as pillar drills
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metal RECycling - key facts
Recycling metals, saves a lot of money and energy. It can reduce the need of mining and can save landfill
space.
Metals are usually made from ores, these ores need to be mined and transported to smelting plants.
These processes non energy efficient.
Ores are non renewable resources and some day the earths supply will run out. It will take millions of
years to replenish the ores already used.
Recycling will make our supply of metals last longer.
Only 42% of aluminium cans sold In the U.K. are recycled.
Recycling an aluminium can saves the equivalent amount of energy needed to run a television for 3
hours.
Many recycling centres collect aluminium drinks cans and steel food cans together. From here these are
separated using high powered electromagnets. Iron in steel is magnetic, while aluminium is not.
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RECYCLING - cars
Recycling cars is more
challenging, due to the variety
of metals and materials used
throughout the vehicle.
In this case it is much cheaper
and more environmentally
friendly, to re-use products.
E.g. car parts, and
components
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Quiz
What is the difference between
Ferrous and Non-Ferrous?
Name three different types of non
ferrous metals?
What are the key benefits of alloys?
what do you add to iron to make
steel?
Name 2 types of physical and
mechanical properties?
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appendiCES
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reference - metals sector
MODEL ILLUSTRATING
THE METALS SECTOR
FROM ITS BASIC FORM
TO ITS PRIMARY USES
ACROSS INDUSTRIES
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WORLD METAL ORE
PRODUCERS
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Canada: Iron= 10.3 million tones.
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U.S.A: Iron = 7.9 million tones. Aluminium = 1.8 million tones.
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Brazil: Iron = 9.6 million tones.
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U.K: Iron = 11.6 million tones. Tin = 2.8 thousand tones.
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Germany: Iron = 30.1 million tones.
•
South Africa: Iron = 5.8 million tones. Manganese = 5,290 thousands tones. Chrome = 3,318
thousand tones.
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USSR: Iron = 108 million tones. Aluminium = 6.7 million tones.
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China: Iron = 29 million tones. Aluminium = 0.9 million tones.
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Australia: Aluminium = 24.3 million tones. Iron 7.4 million tones. Manganese = 1,386 thousand tones.
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