Metals

Unit 4. MetalsUnit 4. Metals What are we going to learn in this What are we going to learn in this

unit?unit?4.1 Know some properties of metals.4.2 The Classification of metals4.3 Describe the process to obtain metals.4.4 The different processes of metalworking4.5 State advantages and disadvantages of recycling.4.6 Final Activities

Unit 4. Metals Unit 4. Metals Which metals do you know?Which metals do you know?

Hardness The resistance a material has to cutting and surface indentations.

ToughnessThis describes the amount of energy a material can

absorb without breaking. This is the opposite to brittleness. We measure a material's ability to absorb shock.

Tensile Strength

The maximum force a material can withstand in tension(pulling) compression(squashing) , torque(twisting) and shearing(sideways pressure).

Malleability The amount of hammering, pressing and shaping a material can take without breaking.

4.1 Properties4.1 Properties

Ductility The length that a material can be stretched without breaking.

Elasticity The length that a material can be stretched and return to its original length when released.

Heat and Electrical Conductivity

The measure of how well a material can conduct heat or electricity.

Heaviness The denseness of materials. A dense material will be heavy in relation to its size.

Strength The measure of how a material withstands a heavy load without breaking.

4.1 Properties4.1 Properties

a The resistance a materials has to cutting and surface indentations.

bThis describes the amount of energy a material can absorb without breaking. This is the opposite to brittleness. We measure a material's ability to absorb shock.

c The amount of hammering, pressing and shaping a material can take without breaking.

d Ductility

e The length that a material can be stretched and return to its original length when released.

fHeat and Electrical Conductivity

g Heaviness

h The measure of how a material withstands a heavy load without breaking.

4.1 Properties4.1 Properties Complete the tableComplete the table

4.2 The Classification of metals Ferrous metalsFerrous metals

Mainly made of iron with small amounts of other materials added in order to give the correct

properties Wrought iron Mild Steel Carbon Steel Cast iron Stainless steel

4.2 The Classification of metals

Wrought ironWrought iron Wrought iron is

almost 100% iron. It is fibrous, tough and ductile. It is used in gates and railings but it is not very used today.


Mild SteelMild Steel It is made out of a few

carbon and iron. It's tough, it gets rusty easily. It has high tensile strength. It's most common used in school workshops and in engineering. It is used in nuts, bolts, screws and car bodies too.


Carbon SteelCarbon SteelIt has more carbon than mild steel and iron. It's

tough and very hard. It is used in cutting tools such as drills and hammers.


Cast ironCast iron It has a lot of carbon (4%). It is strong but

brittle, compressive strength very high. It is used in vices and kitchen pots.


Stainless steelStainless steel It is made out of iron, nickel and chromium. It It is made out of iron, nickel and chromium. It is hard and tough and it is resistant to rust is hard and tough and it is resistant to rust and stains. It is used in cutlery, medical and stains. It is used in cutlery, medical instruments, sinks, and kitchen utensils such instruments, sinks, and kitchen utensils such as pots and pansas pots and pans

4.2 The Classification of metals Complete the tableComplete the table

Properties of Properties of metalmetal

Name of metalName of metal





4.2 The Classification of metalsName of metalName of metal


Mild steel is used for general structural work, eg Mild steel is used for general structural work, eg girders, nuts, bolts, screws, car body panels and girders, nuts, bolts, screws, car body panels and non-cutting tools.non-cutting tools.Tough, malleable, high tensile strength, easily Tough, malleable, high tensile strength, easily joined, poor resistance to corrosion, general-joined, poor resistance to corrosion, general-purpose metal.purpose metal.

Stronger and harder than mild steel, but less Stronger and harder than mild steel, but less ductile, tough and malleable.ductile, tough and malleable.

Medium carbon steel is used to also make garden Medium carbon steel is used to also make garden tools, axles and shafts.tools, axles and shafts.

High carbon steel is used to make hand tools, High carbon steel is used to make hand tools, chisels and punches. It is also called tool steel.chisels and punches. It is also called tool steel.

Hardest of the carbon steels, but less ductile, tough and Hardest of the carbon steels, but less ductile, tough and malleable. Hardness and toughness are improved by heat malleable. Hardness and toughness are improved by heat treatment.treatment.






Non-Ferrous metals and alloysNon-Ferrous metals and alloysThese metals do not contain iron. They are not These metals do not contain iron. They are not

magnetic. magnetic. Alum in iumC opperBrassBronzeS ilverLead

4.2 The Classification of metals AluminiumAluminium

Resistant to corrosionResistant to corrosionLow densityLow densityUsed for greenhouse frames and Used for greenhouse frames and

aeroplane bodiesaeroplane bodies

4.2 The Classification of metals CopperCopper

Good conductor of heat and Good conductor of heat and electricityelectricity

Used for saucepan bottoms and Used for saucepan bottoms and wiringwiring

4.2 The Classification of metals LeadLead

It is bluish grey and a pure metal. It is soft and weak, it is heavy, ductile and it loses its shape under pressure. It is used in solders, pipes, car batteries and roofing..

4.2 The Classification of metals SilverSilver

It is whitish grey. It is made up of mainly silver but alloyed with copper to give sterling silver. It is ductile, malleable, solders and it is resistant to corrosion. It is used in jewellery and ornaments.


AlloysAlloys These are mixtures of two or more These are mixtures of two or more

metalsmetals E.g. brass, bronze, duralumin, solderE.g. brass, bronze, duralumin, solder The properties are different from the The properties are different from the

base metals base metals

4.2 The Classification of metals BronzeBronze

It is yellow-red. It is an alloy of copper and tin. It is hard, it conducts electricity and it has good corrosion properties. It is used in coins, springs and turbines.


BrassBrass It is yellow and it is an alloy of copper and

zinc. It is hard, conducts electricity and it doesn't get rusty. It is used in ornaments and door handles.

NAMENAME COLOURCOLOUR ALLOY OF;ALLOY OF; PROPERTIESPROPERTIES USESUSES AluminiumAluminium Light grey Light grey Aluminium 95%Aluminium 95%

Copper 4%Copper 4%Manganese 1%Manganese 1%

Ductile, soft, Ductile, soft, malleable, malleable, machines well. machines well. Very light. Very light.

Reddish brown Reddish brown Not an alloy Not an alloy Ductile, can be Ductile, can be beaten into beaten into shape. shape. Conducts Conducts electricity and electricity and heat. heat.

Electrical Electrical wiring, tubing, wiring, tubing, kettles, bowls, kettles, bowls, pipes. pipes.

BrassBrass Mixture of Mixture of copper and zinc copper and zinc 65% - 35% 65% - 35% most common most common ratio. ratio.

Hard. Casts and Hard. Casts and machines well. machines well. Surface Surface tarnishes. tarnishes. Conducts Conducts electricity. electricity.

Parts for Parts for electrical electrical fittings, fittings, ornaments. ornaments.

SilverSilver Whitish grey Whitish grey Mainly silver Mainly silver but alloyed with but alloyed with copper to give copper to give sterling silver. sterling silver.

Jewellery, Jewellery, solder, solder, ornaments. ornaments.

4.2 The Classification of metals Complete the tableComplete the table

NAMENAME COLOURCOLOUR ALLOY OF;ALLOY OF; PROPERTIESPROPERTIES USESUSES AluminiumAluminium Light grey Light grey Aluminium 95%Aluminium 95%

Copper 4%Copper 4%Manganese 1%Manganese 1%

Ductile, soft, Ductile, soft, malleable, malleable, machines well. machines well. Very light. Very light.

Window frames, Window frames, aircraft, kitchen aircraft, kitchen ware. ware.

CopperCopper Reddish brown Reddish brown Not an alloy Not an alloy Ductile, can be Ductile, can be beaten into beaten into shape. shape. Conducts Conducts electricity and electricity and heat. heat.

Electrical Electrical wiring, tubing, wiring, tubing, kettles, bowls, kettles, bowls, pipes. pipes.

BrassBrass Yellow Yellow Mixture of Mixture of copper and zinc copper and zinc 65% - 35% 65% - 35% most common most common ratio. ratio.

Hard. Casts and Hard. Casts and machines well. machines well. Surface Surface tarnishes. tarnishes. Conducts Conducts electricity. electricity.

Parts for Parts for electrical electrical fittings, fittings, ornaments. ornaments.

SilverSilver Whitish grey Whitish grey Mainly silver Mainly silver but alloyed with but alloyed with copper to give copper to give sterling silver. sterling silver.

Ductile, Ductile, Malleable, Malleable, solders, resists solders, resists corrosion. corrosion.

Jewellery, Jewellery, solder, solder, ornaments. ornaments.


4.3 Obtaining metals.SteelmakingSteelmaking

4.4 Metalworking4.4 Metalworking

1 1 FormingForming processesprocesses 1.1 Casting1.1 Casting

CastingCasting is a is a manufacturing process manufacturing process by which a liquid by which a liquid material is usually material is usually poured into a mold, poured into a mold, which contains a hollow which contains a hollow cavity of the desired cavity of the desired shape, and then allowed shape, and then allowed to solidify. to solidify.

http://en.wikipedia.org/wiki/Metalworking#Forming_processes




http://en.wikipedia.org/wiki/Metalworking#Casting


1 Forming processes1 Forming processes 1.2 Plastic 1.2 Plastic

deformingdeforming heating until the metal heating until the metal

becomes plastically becomes plastically deformable by deformable by application of application of mechanical forcemechanical force


1 Forming 1 Forming processesprocesses

1.4 Sheet metal 1.4 Sheet metal formingforming

Is simply metal formed Is simply metal formed into thin and flat into thin and flat pieces.pieces.

4.4 Metalworking4.4 Metalworking 2 Cutting processes2 Cutting processes

Tools for cutting metalsTools for cutting metals

Circular saw Scissors Hand sawCircular saw Scissors Hand saw

4.4 Metalworking4.4 Metalworking 3 Joining processes3 Joining processes

3.1 Welding 3.1 Welding


3.1 Brazing3.1 Brazing


3.3 Soldering3.3 Soldering

4.5 Recycling4.5 Recycling Advantages –Advantages – Saves moneySaves money Less damage to environmentLess damage to environment Uses less energyUses less energy Less poisonous wasteLess poisonous waste Disadvantages-Disadvantages- Scrap metal must be collectedScrap metal must be collected Metal must be sorted from other materialsMetal must be sorted from other materials Difficult if metals in small quantitiesDifficult if metals in small quantities Depends on the public sorting their rubbishDepends on the public sorting their rubbish

4.6 Final Activities4.6 Final ActivitiesMetals are used for many different things because they Metals are used for many different things because they

have useful properties. have useful properties. AA malleable (can be hammered or bent into shape)malleable (can be hammered or bent into shape)BB conduct electricityconduct electricityCC conduct heatconduct heatDD strongstrong

For each of the uses below, write down the name of the propertie (or properties) that are useful. For example, saucepans – (saucepans are made of metal because metals conduct heat).

aa electrical wires __________________electrical wires __________________bb bridges ________________________bridges ________________________cc radiators _______________________radiators _______________________dd cars ___________________________cars ___________________________

Documents

Metals