Metals

1. Metals • An overview 13TH OCTOBER 2009

2. 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)

3. 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

4. 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 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

5. EXTRACTION The primary method used for extracting metal ore from the ground is via mining: • 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. 2

6. MINE TO METAL From ‘mine to metal’, this is the process that the Ore goes through to produce Steel. 2. Ore is crushed, separated from surrounding materials by high powered electromagnetic 3. Iron Ore is poured with coke and limestone into the blast furnace - melting it to ‘Molten Iron’ 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’ 4. Molten Iron is sent to the ‘Mixer’ to obtain best result and balance in the metal 3

7. 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 4

8. 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

9. 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

10. 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

11. 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

12. metal types METALS ARE DIVIDED INTO 3 BASIC CATEGORIES: (1)FERROUS, (2)NON FERROUS, (3) ALLOYS METALS NON - FERROUS FERROUS PUREMETALS PUREMETALS ALLOYS ALLOYS

13. metal types - key features • 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 • 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

14. 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.

15. Non-Ferrous metals: common uses • Aluminium • Copper • Gold • Lead 2

16. metal alloyS: properties ALLOYING INCREASES STRENGTH, HARDNESS AND DUCTILITY, ENHANCES RESISTANCE TO CORROSION AND OXIDISATION, CHANGES MELTING POINT, COLOUR AND ELECTRICAL/THERMAL PROPERTIES 5

17. Metal alloys: common uses • Duralumin • brass • bronze • nitinol 2 3

18. 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 carboninto it’s structure

19. Ferrous metals: common uses • Mild Steel • Medium Carbon Steel • High carbon Steel • Cast Iron

20. 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

21. 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

22. 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

23. 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

24. 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. 2

25. 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 4

26. 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?

27. appendiCES

28. reference - metals sector MODEL ILLUSTRATING THE METALS SECTOR FROM ITS BASIC FORM TO ITS PRIMARY USES ACROSS INDUSTRIES

29. 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. 5