Technical Materials (II): Metals

Department of Technology I.E.S. Ramiro de Maeztu

Madrid

Metal Properties• Metal is a good conductor of heat and electricity

• High mechanical endurance

• High fusion temperature • Metal is a heavy material

Cast Iron Steel Copper Tin Zinc Aluminum Magnesium Titanium

Tensile Strength

18 kg 70kg 18kg 5kg 3kg 10Kg 18kg 70kg

Mass(per m3) 7600kg 7800kg 8800kg 7300kg 7400kg 2700kg 1700kg 4500kg

Fusion temperature

1100ºC 1500ºC 1083ºC 231ºC 419ºC 660ºC 650ºC 1800ºC

• It´s a tough material

•Some of them have magnetic properties • It´s an easily recyclable material

• It´s a ductile, malleable material

Metal Properties

Classification of MetalsWorld Metal Production

Metals are classified in two groups:

oFerrous Metals: iron and its alloys.

oNon-Ferrous Metals: metals that do not contain iron .

This is because iron is the most used metal in the world

Ferrous Metals

•Iron is an abundant metal.•Iron is fragile and brittle.•Iron rusts easily.•Iron has very good magnetic properties.

Pure iron

Due to his low endurance, pure iron is not used. So it´s mixed with a little amount of carbon obtaining ferrous alloys.

How changes carbon the iron properties?A bigger amount of carbon in the ferrous alloy increases the hardness

but decreases the tenacity, so the alloy becomes more fragile.

• Soft Iron( C<0,1%)

It´s like pure iron. At first it was very used because it was easy to obtain. At present time it´s used to make electromagnet nucleus thanks to its very good magnetic property.

•Soft, due to its low iron content.•Silvery colour.•Electric and electronic applications.

Ferrous Metals: Ferrous Alloys

• Steel ( 0,1%<C<2% )It´s the most used ferrous alloy thanks to its good properties.•Ductile and malleable.•High mechanical endurance.•The amount of carbon increases hardness and fragility.

Steel mixed with other metal increases endurance (vanadium) and becomes stainless (chrome and nickel).

Ferrous Metals: Ferrous Alloys

• Cast Iron ( 2%<C<5% )

• Harder and more fragile than steel.• It has low ductility but it´s a malleable alloy with magnesium.• It melts more easily (at a lower temperature) than steel.

It´s used to make complicated parts by sand casting (aka sand molded casting) and to make hard tools like rasps.

Ferrous Metals: Ferrous Alloys

Non-Ferrous Metals: Pure Metals• Copper

• Tin

•Red colour•Excellent thermal and electrical conductor•Corrosion resistant•Good welding•Very ductile and malleable

•Bluish white shiny colour•Soft•Corrosion resistant•Low melting point

• Zinc

• Aluminum

•White colour•Very corrosion resistant

• White shiny colour• Light and good endurance• No toxic• Cheap•Stainless

Non-Ferrous Metals: Pure Metals

• Magnesium

• Titanium

•Very light•Expensive•Violent reaction with oxygen

•Very expensive•Endurance like steel but quite lighter.•Biocompatible

Non-Ferrous Metals: Pure Metals

• Gold

• Lead

•The most malleable and ductile metal•Very corrosion resistant•High thermal and electric conductivity•High economic value

•Grey colour•Very soft and heavy•Low melting point•Ductile and malleable•Very toxic

Non-Ferrous Metals: Pure Metals

• Brass (Copper+Zinc)

• Bronze (Copper+Tin)

•Yellow colour•Very ductile and malleable•Good tensile endurance

•Dark yellow colour•More endurance than brass•Very corrosion resistant•Good sonority•Very fluid when melting, good for molding.

Non-Ferrous Metals: Alloys

• Aluminum, Copper & Magnesium

• Magnesium & Aluminum

• Titanium & Aluminum

•Lightness and more endurance than pure aluminum.

•This alloy is more resistant than each metal.

• Cheaper than pure titanium parts.

Non-Ferrous Metals: Alloys

Extraction of metals

Most metals are in nature as minerals.

Chalcosite: copper rich Pyrite: iron rich Hematite: iron rich

Limonite: iron richBauxite: aluminum richPure gold

Obtaining cast iron and steelCoal

Iron ore

Limestone

Blast furnace

Torpedo ladleLadle FurnaceRefining Furnace

We can obtain cast iron by melting of coal,iron ore and limestone at the blast furnace , then we carry it to the refining furnace using torpedo furnace and ladle furnace. In the refining furnace the amount of carbon to obtain steel decreases.

Obtaining of metals by electrolysis

A high voltage electric current through the melted metal is used.Pure metal is attracted by the negative electrode (remember that metal atoms are positive).We can use this method to obtain metals like copper and aluminum.

Metal Working

To cutTo fasten and to bend

To measure and to mark

To smooth or refine

To join

To finish

To drill

•To measure and to mark

•To hold/fasten and to bend

Metal Working Compass

SquareSteel rule

Pliers

Vise , F - clamp and G-clamp

•To cut

•To drill

Metal Working

Metal Scissors Hacksaw

DrillDrill bits

•To smooth/refine

•To joinWelding Screwing Riveting

Metal Working

Rasp

Wire wool

Metal polisher

•To finish

Primer

Burnished

Metal Working

• Milling: we can use different mill bits to shape a piece from a block of metal.

Metal Working: Machining

• Turning: we can obtain metallic parts with cylindrical symmetry.

Metal Working: Machining

• Computer Numerical Control (CNC): it´s to make metallic pieces automatically and with a very high accuracy.

Metal Working: Machining

Molding and Metal Forming

• Moulding: Sand Casting

Sand is used to make a mold and fill this with molten metal. It allows you to make complicated parts as the engine block of a car.

• LaminationWe use rolls that compress the metal to obtain sheets and metal profiles.

Moulding and Metal Forming

• Stamping

• Die-Cutting

A metal sheet is compressed by a press to take the form of the mold.

It´s cutting pieces of a metal sheet using a press.

Molding and Metal Forming

• Forge We use the fire and hammer over the anvil to shape the soft steel and get handmade pieces of metal.

Anvil

Molding and Metal Forming

THE END