you will learn about specifications and properties of materials in Engineering. This is important for engineering students.

1. LECTURER
Mr.Muhammad Sulaiman
m.sulaiman@uet.edu.pk
Department of Chemical, Polymer & Composite Material Engineering
University of Engineering & Technology, Lahore , KSK Campus
3rd LECTURE

2. Physical properties
Density, melting point etc.
Mechanical properties
 Yield strength, tensile strength, compressive strength, ductility,
toughness.
Manufacturing properties
 Ability to be shaped by molding, casting, machining.
Ability to be joined by welding.
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3. Other non-mechanical properties
Electrical, magnetic, optical and thermal properties.
Chemical properties
Oxidation, corrosion.
Economic properties
Raw material and processing costs, availability.
Aesthetic properties
Appearance, texture and ability to accept special finishes.
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4. HYSICAL PROPERTIES
A physical property is any measurable property whose value
describes a state of physical at any given moment.
Intensive property
 Which does not depend on the size or amount of matter in the
object. e.g. density, temperature, pressure.
Extensive property
 Which depend on the size or amount of matter in the object. e.g.
mass, volume.
 Ratio of two extensive property of the same object or system gives
intensive property.
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5. PHYSICAL PROPERTIES
1. Density
2. Melting point
3. Electrical conductivity
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6. DENSITY
Density is defined as a mass per unit volume of a material.
Units: kg/m³
𝜌 =
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𝑉
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8. MELTING POINT
The melting point of a solid is the temperature at which the vapor
pressure of the solid and the liquid are equal.
At melting point, solid and liquid phase exist in equilibrium.
Examples of metal melting points (ºC)
Molybdenum 2620
Nickel 1458
Iron 1535
Brass 900-1050
Copper 1083
Silver 960
Aluminium 660
Antimony 938
Lead 631
Bismuth 272
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9. ELECTRICAL CONDUCTIVITY
Electrical conductivity or specific
conductance is a measure of a
material's ability to conduct an
electric current.
 Example: Copper wire is chosen
for the electric wires because it
has very high electrical
conductivity.
 Pure metals has better
conductivity than alloys
 The non metals are poor
conductors of electricity.
Resistivity: Electrical resistivity is a
measure of how strongly a material
opposes the flow of electric current.
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11. Thermal Expansion
 It is expansion of material due to increase in temperature.
Types
1. Linear Expansion
2. Surface Expansivity
3. Volume Expansivity
Thermal Contraction
 It is contraction of material due to decrease in temperature.

12. Linear Expansion
 This is the expansion in length by rise in temperature.
Lf – Lo/Lo = αl (Tf-To)
Coefficient of Linear Expansion
 It is a measure of amount by which a unit length of the material
expands when its temperature is raised by 1˚C.
Surface Expansivity
 Increase in two dimensions by rise in temperature is called surface
Expansivity.
Volume Expansivity
 Increase in three dimensions by the rise in temp is called volume
expansivity.
ΔV /Vo =αvΔT

13. Thermal Conductivity
 It characterizes a material’s ability to transfer heat.
q = -kA(dT/dx)
 Metals generally have the greatest conductivity.
 Ceramics are insulators
 Polymers are poor conductors.

14. Heat Capacity
 Amount of energy required to produce a unit rise in temperature. It
provides a measure of material ability to absorb heat from the
surrounding environment.
Transition Temperature
 Temperature at which significant changes occurs in the structure of
material.
Melting point
 Temperature where solid and liquid phases are in
equilibrium.
Boiling Point
 Temperature where liquid and gas phases are in equilibrium.

15. Problem
Determine the heat loss through a brick wall 4m by 3m of 0.25
m thickness if the inner surface is maintained at 20˚C and the
outer surface temperature is 5˚C. The thermal conductivity of
brick is 0.5 W/m-K.
Problem
Calculate the heat flow per unit area through a wall of a steel
furnace with a thickness of 1 inch. When the temperature
gradient across the wall is 10˚F. The thermal conductivity of the
steel is 26 Btu/hr.ft.˚F.

16. Fusibility
 Ease with which materials melt.
Temperature Stability or Temperature Resistance
 The ability of material to remain stable with change in
temperature.
Creep
 Creep is defined as the gradual extension of the material
over a long period of time while the applied load is kept
constant.

17. MECHANICAL PROPERTIES
1. Tensile strength
2. Compressive strength
3. Shear strength
4. Elasticity
5. Plasticity
6. Ductility
7. Malleability
8. Hardness
9. Brittleness
10. Rigidity
11. Toughness
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18. a) Compressive Strength
b) Tensile Strength
c) Shear Strength
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19. DUCTILITY
Ductility is the ability of a metal to be stretched into wires
permanently without fracture.
This is the term used when plastic deformation occurs as a result
of tensile load.
Metals that lack ductility will crack or break before bending.
Example is wire drawing.
Copper, aluminum, and steel are ductile material
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20. It can also be expressed as either % elongation or %
reduction in area.
% Elongation = (Lf- Lo/Lo) * 100
% Reduction = (Ao – Af/ Ao) * 100
Lf & Af are the fracture length and cross-sectional area at the point of
fracture respectively.
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21. MALLEABILITY
Malleability is the ability of a metal to be hammered, rolled, or
pressed into various shapes without fracture.
This is the term used when plastic deformation occurs as a result
of compressive load.
Its examples are forging & rolling.
Copper, aluminum, and steel are malleable material
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22. BRITTLENESS
Brittleness is the tendency of a material to fracture without
any plastic or little deformation.
This is opposite of ductility & malleability.
Example: A steel rod is bent easily but a grey cast iron rod
breaks when subjected to bent. So, grey cast iron rod is a
brittle material. Glass is a most common example.
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24. It is the capacity of a material to absorb energy when it is
deformed elastically and then, upon unloading, to have this
energy recovered.
Elastic energy is the potential mechanical energy stored in the
configuration of a material as work is performed to distort its volume or
shape.
Area under the elastic portion of stress-strain curve provides an indication
of material’s resilience.
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25. where
1. so is the proportional limit stress
2. eo is the strain at the proportional limit stress.
3. Ur is important in selecting materials for energy storage such as
springs.
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26. HARDNESS
Hardness is the ability of a metal to resist penetration and
wear by another metal or material.
The hardness of a metal can usually be controlled by heat
treatment.
Hardness Tests:
1. Brinell
2. Vickers
3. Knoop
4. Rockwell
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27. Material Brinell Hardness
Pure Aluminum 15
Pure Copper 35
Mild Steel 120
304 Stainless Steel 250
Hardened Tool Steel 650
Hard Chromium Plate 1000
Typical Hardness Values for Common Materials
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28. It is the measure of material’s ability not to deflect under
an applied load.
Steel is much stronger than cast iron but cast iron is
preferred for machine processing because it is more
rigid and less likely to deflect under an applied load.
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29. Rigidity Testing:
a) Under a light load, cast iron deflects less than steel since it is more rigid
b) Under a heavy load, cast iron breaks, less rigid steel only bends
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31. Measure of ability of material to absorb energy up to
fracture.
Example is high carbon steel (silver steel),ceramics and
concrete.
Any material in which spread of surface crack does not occurs
or only occurs to small extend is said to be tough.
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32. It is the total energy absorption capabilities of the
material to failure.
1. where Su is the ultimate tensile strength.
2. so is the proportional limit stress
3. ef is the strain at fracture.
4. Ut is important in selecting materials for applications where high overloads
are likely to occur and large amounts of energy must be absorbed.
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34. Permeability
It is the ease with which a material can be magnetized.
1. Diamagnetic
2. Ferromagnetic
3. Paramagnetic
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