1. Materials Science Introduction to Materials Properties of Materials
Metals
Plastics
Woods
Composites
Heat Treatment

2. Introduction to Materials
Materials are used to make or build objects.
During the past 200 years there has been an enormous increase in the range of materials available to us. It is therefore important that the correct materials be used for a particular use.
In Selecting the best material you need to look at 4 things: Physical properties, Cost and Time, Shaping and Forming and Availability.

3. Selecting the best material – A checklist
1 PHYSICAL PROPERTIES
Hardness
Tensile Strength
Compressive Strength
Shear Strength
Stiffness
Toughness
Malleable
Corrosive
Appearance
Weight
Conductivity
2 WHAT COST?
The materials
The extras (fittings etc)
SELECTION
3 SHAPING & FORMING
Cutting out Moulding Casting Joining
4 AVAILABILITY
Are they easy to obtain including fittings.

4. Properties of Materials
Each material has many properties. It is incorrect, for example to describe a material as just ‘strong’ or ‘weak’ as for example concrete is strong in compression but weak in tension.
Hardness Toughness Strength
Brittleness Malleability Ductility
Elasticity Plasticity Conductivity
Density Fatigue Stiffness

5. The ability of a material to resist wear indentation and scratching.
Hardness
The ability of a material to resist wear indentation and scratching.
An example of a hardness test that can be carried out in the lab.
Different materials are used and the depth of indentation measured

6. The ability of a material to withstand blows or sudden impact.
Toughness
The ability of a material to withstand blows or sudden impact.
Different materials are used, the hammer is swung from the same height each time about a fixed fulcrum. The distance travelled after impact or fracture is used to find toughness

7. Strength
The ability of a material to withstand forces of tension, compression and torsion
Tensile Strength – the ability to withstand pulling forces or Tension forces
Compressive Strength – the ability to withstand ‘squeezing’ forces or Compression forces
Torsional Strength – the ability to withstand ‘twisting’ forces or Torsion forces

8. Brittleness
A material that is easily fractured by impact is said to be brittle e.g. Glass
The same as the toughness test however those materials that fracture easily are said to be brittle.

9. A material that can be rolled or hammered into shape without rupture.
Malleability
A material that can be rolled or hammered into shape without rupture.
As ring rises the side of Coke can is thinned out

10. Ductility
A material that can be pulled or stretched into a thin wire or thread.
Get picture of wire drawing

11. Elasticity
The ability of a material to return to its original shape after deformation.
Get picture of someone stretching elastic band

12. Plasticity
The ability of a material to be permanently deformed without fracture..

13. Conductivity
The ability of a material to allow Heat or electricity to flow through it.
Ball Bearing drops from most conductive 1st.

14. Density
Is the mass of 1 cubic centimetre (cm3) of a substance. (Mass per unit Volume)
Which is heavier a tonne of feathers or a tonne of lead?
Q. Which has the greatest density?
Mass
Density =
Volume

15. Fatigue
Occurs when materials have become overworked and fracture or fail.
Find picture

16. Stiffness
The ability of a material to resist bending deformation.

17. There are two types of metals
Ferrous
Non- Ferrous

18. Ferrous Metals
All the metals in this group contain Iron. They include wrought iron, mild steel and cast steel. Ferrous metals rust easily when exposed to the atmosphere and are magnetic.
Plain Carbon Steels
Alloy Steels

19. Plain Carbon Steels
These steels are a series of iron and carbon alloys with carbon content varying between 0.05% and 1.4%
Dead mild Steel
Low carbon content %.
Ductile and easily formed
Uses: chains, rivets, nails, thin wire

20. Mild Steel
carbon content %.
Bright mild and Black mild, Bright mild used in benchwork Black mild used for forging
Ductile, easily cut, machined and welded, cannot be hardened or tempered
Uses: General engineering work, girders, plates for ship building, gates.

21. Medium Carbon Steel
carbon content %.
Greater strength than mid steel but not as ductile or malleable.
Uses: Axles, rail tracks,spades wire ropes..

22. High Carbon Steel (Cast Steel)
carbon content %.
Hard and wear resistant can be hardened and tempered.
Uses: Cutting tools (chisels, saws, files) dies punches springs hammers..

23. Silver Steel
carbon 1.0%, contains chromium
Does not contain silver gets its name from appearance
Uses: Scribers and screwdriver heads.
Tool Steel
Used for making engineering tools.

24. Tinplate
Tinplate is produced by coating thin sheets of steel containing 0.1% carbon with Tin.
The process of coating the steel is called Electro-plating.
Uses: for food containers. It is also used as containers for many other products such as paint, lubricants etc.

25. Galvanised Iron
This is mild steel coated with Zinc.
The coating is usually achieved by dipping the steel article in a bath of molten zinc.
Uses: for roof sheeting, gates, water tanks, dust bins and other outdoor articles.

26. Alloy Steels
These steels are produced from adding elements such as chromium, tungsten, nickel and manganese to steel.