an easy way to define

1. Knowledge of material
properties
 application
 design of components
 material protection (from corrosion, damage, etc.)

2. Material properties
1. Physical properties
2. Mechanical properties
3. Chemical properties

3. Properties of materials
Mechanical properties of materials
Strength, Toughness, Hardness, Ductility,
Elasticity, Fatigue and Creep
Physical properties
Density, Specific heat, Melting and boiling point,
Thermal expansion and conductivity,
Electrical and magnetic properties
Chemical properties
Oxidation, Corrosion, Flammability, Toxicity, …

4. Failure in Tension, Young’s modulus and Tensile strength
Engineering stress = s = P/Ao
Engineering strain = e = (L – Lo)/Lo = d/Lo

5. Failure in Tension, Young’s modulus and Tensile strength..
Original
Final
Necking
Fracture

6. Failure in Tension, Young’s modulus and Tensile strength…
In the linear elastic range: Hooke’s law : s = E e or, E = s/e
E: Young’s modulus

7. True Stress, True Strain, and Toughness
Engg stress and strain are “gross” measures:
s = F/A => s is the average stress ≠ local stress
e = d/Lo => e is average strain
Final
Necking
Fracture
engg strain d/Lo true strain ln(L/Lo)
true stress P/A
engg stress P/Ao
fracture
fracture
Toughness = energy used to fracture
= area under true stress-strain curve

8. Ductility
Measures how much the material can be stretched before fracture
Ductility = 100 x (Lf – Lo)/Lo
High ductility: platinum, steel, copper
Good ductility: aluminum
Low ductility (brittle): chalk, glass, graphite
- Walkman headphone wires: Al or Cu?

9.  malleability – the property of a material that can be
worked or hammered or shaped without breaking
 brittleness –breaking or shattering of a material when
subjected to stress (when force is applied to it)

10. Physical properties
 colour –light wave length
 specific heat – the heat required to raise the
temperature of one gram of a substance by one
degree centigrade (J/kg K)

11. Physical properties
 density – mass per unit volume expressed in such units
as kg/cm3
 thermal conductivity –rate at which heat flows through
a given material (W/m K)

12. Physical properties
 melting point – a temperature at which a solid begins
to liquify
 electrical conductivity – a measure of how strongly a
material opposes the flow of electric current (Ω⋅m)

13.  coefficient of thermal expansion – degree of expansion
divided by the change in temperature (m/°C)

14. Mechanical properties
 tensile strength – measures the force required to pull
something such as rope,wire or a structural beam to
the point where it breaks
 ductility – a measure of how much strain a material can
take before rupturing

15.  malleability – the property of a material that can be
worked or hammered or shaped without breaking
 brittleness –breaking or shattering of a material when
subjected to stress (when force is applied to it)

16.  elasticity – the property of a material that returns to its
original shape after stress (e.g. external forces) that
made it deform or distort is removed
 plasticity - the deformation of a material undergoing
non-reversible changes of shape in response to
applied forces

17. Mechanical properties
 toughness – the ability of a material to absorb energy
and plastically deform without fracturing
 hardness – the property of being rigid and resistant to
pressure; not easily scratched

18. Mechanical properties
 machinability – the property of a material that can be
shaped by hammering, pressing, rolling

19. Chemical properties
 corrosion resistance - a material's ability to resist
deterioration caused by exposure to an environment

20. Which properties do the
following materials possess?
Material Properties
aluminium lightness ; strength
rubber elasticity ; insulation
ceramics thermal resistivity
steel strength
copper conductivity ; corrosion resistance
lead high density; ductility
nylon strength ; toughness
cast iron damping capacity
wood insulation ; environmental friendliness

21. Find application for the
following engineering
materials:
Material Application
aluminium foil; aircraft; window frame
rubber tyres,; seal; gasket
ceramics furnace; brick
steel section; pipe
copper pipe; cables
lead storage battery; radiation protection
ballast; bullets
nylon rope; clothing
cast iron engine block; valves
wood furniture; deck

22. material with greatest
density
gold - 19300 kg/m3
uranium - 19100 kg/m3
lead - 11340 kg/m3
steel - 7800 kg/m3

23. the strongest material
Material Tensile Strength UTS (Ultimate Tensile
Strength)
carbon nanotubes 62000 MPa
(theoretical300000 MPa)
48000 kNm/kg
carbon fibre 5650 MPa 3200 kNm/kg
glass fibre 4700 MPa 1340 kNm/kg
spider web 1000 MPa 900 kNm/kg
high-strength steel 1200 MPa 154 kNm/kg

24. the best conductor
Material Conductivity
silver 63 x 106 S/m (1/ohm)
copper
59.6 x 106 S/m (1/ohm)
gold
45.2 x 106 S/m (1/ohm)
aluminium
37.8 x 106 S/m (1/ohm)

25. the best insulator
Material Specific resistance
polyethylene terephthalate (PET) 1020 ohm
glass 1014 ohm
rubber 1013 ohm

26. Processes:
Forging - a manufacturing process
where metal is shaped by plastic
deformation under great pressure into
high strength parts.
Casting – pouring or injecting molten metal into a mold
containing a cavity with the desired shape

27. stiffness
 The stiffness of a component means how much it
deflects under a given load.