Properties and Techniques

By:Mel Fàbregas, Yeray Freire, Lara Hosking andAra Forcadell.

Metals

Description:● The metals can be used in many ways:

transport, telecommunications, machinery, construction and manufacturing.

● Metals are usually: · Hard · Non-adhesive · Cold and Smooth · Often shiny

PropertiesThere are 3 types of properties:

· Physical: A physical property is any property that is measurable whose value describes a state of a physical system.

· Chemical: A chemical property is any of a material's properties that becomes evident during a chemical reaction.

· Ecological: A ecological property is any material that can be recyclable and reusable, however it also can be toxic.

Physical PropertiesPHYSICAL PROPERTIES CHARACTERISTICS

Strong (mechanical strenght) Resists forces while not becoming deformed easily

Ductile and malleable Can be made into wire or into thin sheets

Tough They don’t break easily

Plastic and elastic You can bend it and it will return to it’s original shape

Electrical, thermal and acoustic conductivity

Good conductors of electricity, heat and sound

Magnetic They attract some metals

Fusible They can be easily welded to another metal object

Expansion and contraction They expand when the temperature rises, and contract when the temperature falls

Where and how metals are obtained

We obtain the metals from the minerals in rocks.

• Surface mining: When the mineral is near the surface.

• Underground mining: When the mineral is deep.

when we mine, we use explosives, excavators, drills and other machines.

The minerals are separated into ore and gangue.

The metal is extracted with an iron work through a physical and chemical process.

The metals can be ferrous and nonferrous.

Ferrous materialsCaracteristics:

·Common·inexpensive to extract·need processing to produce pure iron·used to make alloys

·Pure iron: The concentration of carbon is between 0.008% and 0.03%.

·Steel: The concentration is between 0.03% and 1.76%.

·Cast iron: The concentration is between 1.76% and 6.67%.

Ferrous Materials: Pure iron and cast iron· PURE IRON: It’s a greyish white metal with good magnetic

properties.

·CAST IRON: It’s extremely hard and resistant

Uses: machinery parts, pistons, street lamps, drain covers,...

DISADVANTAGES USES

Corrodes easily

Only melts in a very high temperature

Electrical and electronic components

It’s difficult to machine

Ferrous materials: steelSteel is an alloy of iron containing a small quantity of carbon. It is

very hard and strong, and because of this it has better mechanical properties than iron.

Up next there is a Alloy steel group and then the steel making process.

Alloy steelsOther chemical elements can be added to steel, to improve or

achieve certain properties. Here are some common examples:

· Silicon · Tungsten

· Manganese · Chrome

· Nickel · Lead

The steelmaking processStages in the steelmaking process:

1. Iron metal is washed to remove impurities.

2. It is crushed and sieved (the gangue is separated from the ore.)

3. The iron ore is mixed with carbon and limestone

4. This is melted at a temperature of over 1.500 C in a blast furnace.

5. Pig iron is obtained (molten iron with carbon and impurities).

Non-Ferrous metals

Light and ultra-light metals: they are separated by aluminum, magnesium and titanium.

Heavy metals: they are separated by: lead, tin, zinc, copper, bronze, brass.

Non-Ferrous materials: Light and ultra light metalsThey are classified in:Aluminium: Used for high voltage powerline, planes, cars,

bicycles, light metal work,roofing, decoration,...

Magnesium:Used for pyrotechnics (fireworks), the aerospace and car industries and bicycles.

Titanium:Used to aerospace industry, building structures,...

Non-Ferrous Materials: Heavy Metals

Lead: batteries, active in glass,...

Tin: Tin foil and tin plate,...

Zinc: Roofing, plumbing,...

Copper: Electrical wire, telephone lines,... Bronze: sculptures, nuts, church bells,...

Brass: jewellery, plumbing,..

Shaping techniques

There are different processes and techniques to shape metals depending on the type of metal and object we want to make.

They are classified in:

• Shaping

• Powder metallurgy

• Casting

Shaping techniques: shaping

Shaping is a technique used to modify shapes.

• Rolling

• Extrusion

• Forging

• Press forging

• Punching

• Bending

• Wire drawing

Shaping techniques: Powder MetallurgyThis process has five stages: 1st: The metal is ground into powder. 2nd: It is pressed into steel dies. 3rd: It is heated to a temperature close to 70% of the metal's melting point.

4th: Pressure is applied to produce the required dimensions.

5th: The object is left to cool (it loses heat)

Shaping techniques: Casting

The mould can be made from sand, steel or cast iron. The casting process:

1. The metal is heated to melting point.2. The liquid metal is poured into the mould.3. The mould and metal are left to cool until the

material has solidified.4. The solidified piece is extracted from the mould.

Casting: Centrifugal casting

It’s a technique that uses a mould which rotates when the liquid metal is poured inside.

Cutting, joining and finishing techiniques:Hand tools or power tools are used to cut prefabricated materials.

They also, are classificated by: · Marking · Rough finishing · Cutting · Permanent joints · Drilling · Temporary joints · Shaping · Finishes

THE END