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MetalsAn 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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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 Aluminium in its pure form is discovered, and is worth more then gold. Bars are on exhibition with the French Crown Jewels.

1890 AD Aluminothermirc Steel, a process taking the metal to high temperature and mixing in aluminium. Similar to stainless steel.

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,

FUTURE of METAL. The future of metal is exploring more uses for them, manipulating them to give added strength, and advantages over other materials. This will be seen in space travel, and satellites plus in the pursuit for more efficient electronics and energies. 1

HISTORY TIMELINE

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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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EXTRACTION

The primary method used for extracting metal ore from the ground is via mining:

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MINE TO METAL

1.Iron Ore is extracted from Mine

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

2. Ore is crushed, separated from surrounding materials by high powered electromagnetic

From ‘mine to metal’, this is the process that the Ore goes through to produce Steel.

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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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TRADING

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Metal properties (1)

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

METALS ARE DESCRIBED BY THEIR PHYSICAL, MECHANICAL AND CHEMICAL PROPERTIES.......

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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

FERROUS NON - FERROUS

PUREMETALS

PUREMETALSALLOYS ALLOYS

METALS ARE DIVIDED INTO 3 BASIC CATEGORIES: (1)FERROUS, (2)NON FERROUS, (3) ALLOYS

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metal types - key features

Ferrous Metals

contain Iron

Are almost all magnetic

Unless treated, corrode very easily

Non-Ferrous metals

contain no Iron

Not magnetic

More resistant to corrosion

pure metals

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 alloying metals. Metal AlloysMost alloying is done by mixing the ingredients of the alloy in their liquid stateSuccess depends on the property of fusibility.

Stronger and lasts longer than either pure metal

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

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non-ferrous metals: properties

Metal Physical PropertiesMechanical Properties

AluminiumCorrosion 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,

GoldGood resistance to oxidation and an excellent conductor of

electricity

Gold is dense, soft, shiny and the most malleable and

ductile pure metal known.

LeadHigh resistance to

atmospheric conditions, poor electrical conductivity

Very soft, Highly malleable, Dense, Ductile, When alloyed

with tin makes soft solder

PURE METALS ARE OFTEN TOO SOFT TO BE OF PRACTICAL USE, WHICH IS WHY MUCH OF METALLURGY FOCUSES ON THE FORMULATION OF USEFUL ALLOYS.

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Non-Ferrous metals: common uses

Aluminium

Copper

Gold

Lead

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metal alloyS: properties

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AlloyBase Metal

Composites

Physical Properties

Mechanical Properties

Duralumin

Aluminium4% Copper

1% Manganese0.1% Magnesium

With Titanium keeps the strength

when hot, Magnesium makes

metal harder

Harder than normal Aluminium

Hardens with age

Brass Copper35% Zinc

1%-2% Lead/Tin

Tin produces increased

resistance to corrosion

Works well when hot, Malleable, Ductile, Polishes

well and Solders easily

Bronze

Copper 10% TinTough, resists corrosion,

casts well, malleable, solders and brazes easily

Nitinol Nickel50%Nickel

50% Titanium

Physiological and chemical

compatibility with the human body

Smart Metal Alloys (SMAs) with Shape Memory and

Super-elasticity

ALLOYING INCREASES STRENGTH, HARDNESS AND DUCTILITY, ENHANCES RESISTANCE TO CORROSION AND OXIDISATION, CHANGES MELTING POINT, COLOUR AND ELECTRICAL/THERMAL PROPERTIES

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Metal alloys: common uses

Duralumin

brass

bronze

nitinol

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ferrous metals: Properties

Metal Physical PropertiesMechanical Properties

Mild Steel Poor resistance to corrosionTough, Ductile, Malleable

Good Tensile StrengthEasily joined (Welding or Brazing)

Medium Carbon Steel

Better resistance to corrosion Tougher, harder but less ductile

High Carbon Steel

Good resistance to corrosionVery tough,Very hard, MalleableCan be hardened and tempered,

even less ductile

Cast IronExcellent resistance to deformation, and wear resistance

Brittle, low melting point, good fluidity, castability, excellent

machinability,

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

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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

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

THE PROCESS OF HEATING & COOLING METALS TO CHANGE THE PROPERTIES OF THE MATERIAL

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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

in the workshop - joining metals

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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

• Canada: Iron= 10.3 million tones.

• U.S.A: Iron = 7.9 million tones. Aluminium = 1.8 million tones.

• Brazil: Iron = 9.6 million tones.

• U.K: Iron = 11.6 million tones. Tin = 2.8 thousand tones.

• Germany: Iron = 30.1 million tones.

• South Africa: Iron = 5.8 million tones. Manganese = 5,290 thousands tones. Chrome = 3,318 thousand tones.

• USSR: Iron = 108 million tones. Aluminium = 6.7 million tones.

• China: Iron = 29 million tones. Aluminium = 0.9 million tones.

• Australia: Aluminium = 24.3 million tones. Iron 7.4 million tones. Manganese = 1,386 thousand tones.

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