ENGINEERING MATERIALS
CONTENTS
Sl.No.
Chapter Name
Page No.
01
Engg. Materials & their properties
02-05
02
Ferrous Materials and alloys
05-07
03
Iron-Carbon system
07-12
04
Crystal Imperfections
13-17
05
Heat Treatment
18-29
06
Non-ferrous Alloys
29-36
07
Bearing Materials
37-39
08
Spring Materials
39-41
09
Polymers
41-43
10
Composites & Ceramics
44-45
Page 1
ENGINEERING MATERIALS
1ST CHAPTER
ENGINEERING MATERIALS AND THEIR PROPERTIES
2 Marks
Q.1 What is materials?
Ans: Material is something that out of which anything can or can be made from it.It consists of matter.
Q.2 Give two example of ferrous and non-ferrous metals?

Example of ferrous metal-cast iron, steel

Examplesof non-ferrous metal-Zinc, Copper.
Q.3 Give two example of non-ferrous metal?
Ans: copper and Zinc.
Q.4 State the application of ceramic?
Ans:-Ceramic material can be used as sand,glass, bricks,cement.
Ceramic material are corrosion resistance and be used as concrete,insulator,abrasives,refractories
and plaster.
Q.5Give four important characteristics of ceramics?
Ans:1.Brittleness
2.Resistance to high temperature.
3.Hardness
4.It is insulator.
Q.6Classify composite material?
Ans:-The materials which are produced by combining of two dissimilar materials in to new materials
that may be better suited for a particular application then the original material is called composite.
The base materials which is present in large amount is called matrix.The other material is sometimes
known as reinforcing phase.
5 MARKS
Q.1 Classify material?
Ans:Most engineering material can be classified as follows
(a)metals
*ferrous
*non ferrous
(b)Ceramics
(c)Organics
(d) Composites
(e) Semiconductors
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ENGINEERING MATERIALS
7 MARKS QUESTIONS AND ANSWERS.
Q.1.What are the various factor affecting the selection of materials?
Ans: The wide varieties of material exhibiting diversified properties are available and necessary to use
materials having properties suitable for the application .and selection a suitable material among the
materials available is a very complex process, involving risk factor and therefore several factors has to
be taken in to account .the factor affection the selection of materials for engineering purpose are the
following.
(A)Properties of material:
Themost important factor affecting the selection of materials in relation to their intended for
use.
The properties of material define specific characteristics of material and form a basis for predicting
behavior of the material under different condition.
The important properties of materials are
 Mechanical(stress),
 thermal (heat/cold),
 Chemical (atmosphere,water,chemicals),
 Electrical (power,current),
 Magnetic
 Radiation(light,ultraviolet)
(B)Performance requirement:
* The material of which a part is composed must be capable of performance the function
without failure
* While it is not always possible to assign quantitative values to these function requirement
they must be related as precisely as possible to specified value of required properties.
(C)Reliability of material:
A material in a given application must also be reliable ,simply stated reliability is the degree of
probability that a product and the material of which it is will remain stable enough to function in service
for the intended life of the product without failure. A material if it corrodes under certain conditions,
then it is neither stable non reliable for those conditions.
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ENGINEERING MATERIALS
(D)Safety
A material must perform its function otherwise the failure of the product made out of it may be
catastrophic as in air plane turbines, high pressure system. The materials that give of spark when
struck are hazardous for use in coal mines.
(E) Physical attributes
The physical attributes such as configuration,size,weight and appearance sometime serve
functional requirementfor ex.the functioning of a gyroscope or a fly wheel is directly related to the
weight of material used.
(F)Environmental conditions
The environment in which a product operates strongly influence the service performance
.humidity, water,chemicals can cause corrosion and subsequent failure of materials.
(G) Availability
Obliviously a material must be readily available and available in large quantity for the intended
application .in time of material scarcity this constraint becomes significant. In future with the projected
scarcity of many material resources important.
(H) Disposability and recyclability
These are the newest of constraints and increasingly important factors in the material
selection. This factor assumes very important in disposability and recyclability of nuclear fuels/material
and plastic.
Cost perhaps more often than any other constraints is the controlling factor in a given material
application problems. For in every application there is cost beyond which one can be not go that
prescribes the limit that can be paid for a material to meet the application requirement. It is becomes
apparent that this limit will be exceeded the design will be changed to alter material requirement .this
fact of limiting cist is as true in aerospace field as in consumer products fields. The only different is
that the limiting cist in aerospace system is considerably higher than for consume products.
The total original cost if material for a given application is made up of two components the
cost of material and the cost of processing the material in to finished product part of product.
Material selection: One of the most important requisites for the development and manufacture of
satisfactory product at minimum cost is to make a sound economic choice of materials.
The selection process:
The material selection processinvolve the following major operation.The Analysis of material
application problem this requires the study of the material performance requirements, including
functional performance physical attributes and application conditions.
The translation of material application requirements material property values .insome cases
this is relatively easy as in part where unidirectional stresses are involved.Here mechanical strength
properties, such as yield and compressive strength can directly derived from the measured applied
loads encountered in the application.
Selection of candidate materials once the required properties are clearly specified the rest of
the selection process involves the search for the material that best meets those properties.
In choosing candidate material any one or more of a number of criteria can be used .past
experience and materials being currently used are often guides to the starting points. Another method
is to base the selection on the most important and critical requirement, different approaches to the
solution of materials problem as distinct from simply choosing candidate’s material for evaluation
should be considered.
Evaluation of candidate material ,the objective of evaluation step is to weight the candidate
material against the specified propertied to find one best suited for application .in principle this step is
a continuation of previous one in that it is essentially an elimination or screening operation.
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ENGINEERING MATERIALS
Q.2 Classify ceramics?
Ans:- The ceramic material may be divided in to three classes
 Clay product
 Refractories
 Glasses
Ceramics material also are classified in the following ways
 Functional classification of ceramics.
 Structural classification of ceramics.
(a) Functional classification:
Group
Example
1.Abrasives
Alumina, Carborandum.
2.Pure oxide ceramics
MgO,Al2Oᴈ,SiO2
3. Fire clay product
Bricks,Tiles,Porcelain.
4. Inorganic glass
Window glass, lead glass etc.
5.Cementing material
Portland cement, lime etc.
6. Rock
Granites,sandstonesetc.
7. Mineral
Quartz,calcite etc.
8. Refractories
Silica brick,Magnetiteetc.
(b) Structural classification.
Group
Examples
1.Crystallineceramics
Single phase like Mg O or multiphase fromMg O to Al 2 O 3
system.
2.Non crystalline ceramics
Natural and synthetic inorganic gears (i.e. window glass)
3.Glass bonded ceramics
fire clay products
4.Cementcrystalline
2ND CHAPTER
FERROUS MATERIALS AND ALLOYS
2 MARKS
Q.1.What are the characteristics of ferrous material?
 Ans:-.Ease of fabrication process.
 Resistance to corrosion.3.Magnetic properties.&4.weight.
Q.2.Classification of low carbon steel?
Ans:-3Types
 Low carbon steel
 Medium carbon steel,
 High carbon steel.
Q.3.What is steel?
Ans:-Steel is an alloy of Iron and Carbon.
Q.4.What is an alloy steel?
Ans:A steel in which elements other than carbon are added in sufficient quantity in order to obtain
special properties is known as alloy steel.
Q.5.What is the use of vanadium steel?
Ans:-Widely used for making steels,it may be used for shafts,spring gears,& drop forged paints.
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ENGINEERING MATERIALS
5 MARKS
Q.1.What are the purposes of alloying?
Ans:To improve elasticity.
To improve corrosion and fatigue resistance.
To improve hardness,toughness &tensile strength.
To improve machinability.
To improve high/low temp.stability.
To improve cutting ability.
To improve wear resistance.
To improve ductility.
To strengthen the ferrite.
Q.2.What is high speed tool steel?
 Ans:-They are widely used for cutting of materials where hardness must be retained at
elevated temperature.
A common analysis
 Tungsten(w)-18%,
 Chromium -04%,
 Vanadium-01%,
 Carbon-0.6-0.7%,
 termed as 18:04:01
 Steel as its improves hardness and cutting ability from 05 to 10% used.
Q.3.Write short note on Manganese steel.
Ans:Manganese steel: More manganese reduces strength manganese steels show high percentage of elongation.
 Heat treated cast manganese steel in bar from is so ductile that it can be bent double when
cold without fracture.
Sp.gr=7.9
Melting point=1343 degree Celsius
 Manganese steel is wieldable.
USE: Jaws of stone & ore crushers, tramway& railway point crossing etc.
 Others applications include agricultural implements such as shovel.
7 MARKS
Q.1.What are the various tool effect of alloying element?
Ans:-1.Chromium:
 Provides stainless property in steel.
 Used widely in stainless steel.
 Used in electric plates.
2.Manganese:
 Counteracts brittleness from sulpher to improve
 Improve response to heat treatment.
 Lower both ductility and malleability of it.it is present in high percentage with high carbon
content in steel.
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ENGINEERING MATERIALS
3.Nickel: Increase toughness.
 Improve response to heat treatment specially large sections.
 In large amount provides special electrical and magnetic properties.
 Improve forming properties of stainless steel.
4.Vanadium: Improve response to heat treatment.
 Provides control of structure.
 Used in high speed tool steels.
5.Molybdenum: Enhances corrosion resistance.
 Makes steel usually tough at various hardness levels.
 Promotes hardenability of steel.
 Forms abrasion resisting particle.
 Raise tensile and creep strength at high temperature.
 Makes steel fine grained.
6.Tungsten: Retention of hardness and toughness at high temperature.
 Used in tool dies ,valves,magnets etc.
3RD CHAPTER
IRON-CARBON SYSTEM
2MARKS
Q.1. Write down the paratactic reaction in the equation of iron carbon equilibrium diagram?
Ans:- It is the reaction that occurs during the solidification of some alloys where the liquid phase
reacts with solid phase to give a solid phase of different structure.
Equation: liquid+solid1→new solid2
Q.2. What is Ledeburite?
 Ans: Aneutectic mixture of austenite and cementite is known as ledeburite.
 It is formed at around 2230°c and carries above 0.8% carbon.
Q.3. What is tempering?
It is the process of reheating a quench hardened steel to reduce its internal stress and to
increase its toughness.reheating is done to a temperature varying from 250°c to 680 °c.depending
upon the reheating temperature the process is called low temperature tempering,medium temperature
tempering or high temperature tempering.
5 MARKS
Q.1. Name the alloys used for high temperature service.
Ans: The various high temperature alloys are
Austenite, Stainless steels.
Ni 34%Cr 4%, and Fe 62% alloy
Page 7
ENGINEERING MATERIALS
Ni 80%, And Cr 20% alloy
A number of non iron ferrous material have been developed that possess high strength and corrosion
resistance at temperature up to 1100°c. the non-ferrous alloys are udimet-500, Inconel 601, haste
alloy-X and vanadium.
7 MARKS
Q.1.With neat diagram, explain the iron-carbon equilibrium diagram?
Ans:The structure form of pure iron at room temperature is called ferrite or α-iron, ferrite is
soft and ductile. Since ferrite has a body centered cubic structure, the inter-atomic space are
small and pronouncedly oblate and cannot readily accommodate even a small carbon atom.
Therefore, solubility of carbon in ferrite is very low, of the order of 0.006% at temperature. The
maximum carbon content in ferrite is 0.05% at 723°c .in addition to carbon a certain amount
of silicon, manganese and phosphorous may be found in ferrite.

The face centered modification of iron is called austenite or γ-iron .it is the stable form of pure
iron at temperature between 910°c and 14400°c. at its stable temperature austenite is soft
and ductile and consequently, is well suited for manufacturing processes. The face centered
cubic structure of iron has large inter atomic spacing than in ferrite. Even so, it FCC structure
the interstices are barely large enough to accommodate carbon atoms, and lattice strains are
produced .as a result, not all the intestinal sites can be filled at any one time. The maximum
solubility is only 2% of carbon at 2230°c.

Above 1400°c austenite is no longer the most stable form of iron, and the crystal structure
changes back to a body- centered cubic phase called δ-iron. This is the same phase as the αiron expect for its temperature range. The solubility of carbon in δ-ferrite is small, but it is
appreciably large than in α-ferrite, because of higher temperature the maximum solubility of
carbon in δ-iron is 0.1% at 1490°c.

In iron –carbon alloys, carbon in excess of the solubility limit must form a second phase,
which is called iron carbide or cementite. Iron carbide has the chemical composition of FeᴈC.
This does not mean that iron carbide forms molecules of FeᴈC has an orthorhombic unit
celland thus has a carbon content of 6.67%.

As compared to austenite and ferrite,cementite being an inter –metallic compound, is
veryhard and brittle. The presence of iron carbide with ferrite in steel greatly increases the
strength of steel.

The iron carbon equilibrium diagram is shown in fig. the solidification of the liquid iron and
carbon melt beings along the liquid denoted in the figure by ABCD. Above the liquids the alloy
is in a liquid state and is a homogeneous system. Along the liquids AB the crystals of the solid
solution of carbon in γ-iron are separated from the liquid.
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ENGINEERING MATERIALS
)
 Crystals of austenite are separated from the liquid along the line BC with the composition
ranging from 0.18 to 2.0%.the complete solidification of these alloys proceeds along the
solidus line HJE. Those with 2.o to 4.3% carbon are completely solidified on line EC. The
solidification of the last portion of the liquid phase, enriched in carbon to 4.3% takes along this
line.All this liquid is completely solidified at 1130°c, at the same time crystals of austenite
containing 2% carbon and cementite containing 6.67% carbon get separated from it. The
solidification of alloys containing 4.3 to 6.67% carbon begins along line CD with the
separation of primary cementite from the melt.
 At the lower temperature,the eutectoid reaction,i.e.formation of two solid from a single solid
occurs at a temperature of 723°c. this is called the eutectoid temperature and the composition
at which this reaction occurs (0.80% c)is called the eutectoid composition. The reaction may
be shown as follows:
 Solid= solid2+solid3
 In the reaction,the simultaneous formation of ferrite and cementite from austenite result at the
temperature of 723°c and composition of 0.80% carbon. There are nearly 12%of iron carbide
and slightly more than 88% of ferrite in the resulting mixture. Since the ferrite and cementite
are formed simultaneously. They are intimately mixed. Characteristically the mixture is
smaller,i.e. it is composed of alternate layer of ferrite and cementite. This microstructure is
called pearlite which is very important in iron and steel technology, because it can be formed
in almost all steel by means of suitable heat treatments.
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ENGINEERING MATERIALS

The alloy containing 0.80% of carbon is called the eutectoid steel. Upon cooling the eutectoid
steel below 723°c all of the austenite is transformed in to pearlite. Alloys with less than 0.80%
c are called hypo-Eutectoid steels and those with higher composition are called hypereutectoid steels.

When hyper-eutectoid steels are cooled below line SE,the austenite decomposes with the
separation of cementite. Since this cementite contains 6.67% c the carbon concentration in
the remaining austenite changes continuously along the line Se until the eutectoid
composition of 80%c.

The iron carbon equilibrium diagram has a peritectic (point j)an eutectic (point C) and an
eutectoid (point S) .Peritectic reaction equation may be written as
Delta(δ)+Liquid= Austenite

The horizontal line at 2720°F shows the Peritectic reaction.

The eutectic reaction takes place at 2066°F and its equation may be written as
Liquid =Austenite+Cementite

Eutectic point is at 4.3% carbon. Eutectic mixture is not usually seen in the microstructure.
Because austenite is not stable at room temperature and must undergo another reaction
during cooling.

The eutectoid reaction is represented by the horizontal line 1333°F and (point)S marks the
eutectoid point. The eutectoid equation may be written as
Solid = Ferrite+Cementite
Q.2Describe different types of hardening methods?
Ans: hardening:

Hardening is define as heating the steel to a temperature within or above its critical
temperature and held at this temperature for a considerable time to ensure proper
penetration of the temperature inside the component and then allowed to cool by
quenching in water, oil, or brine solution.

If the carbon content of steel is known the proper temperature to which the steel
should be heated may be obtained by the iron –carbon equilibrium diagram.
Purpose: Improves strength and toughness
 Improves ductility
 To develop hardness and wear resistance properties,
 To developed mechanical properties.
 Process: the steel is heated to a temperature of 790-850°c. the steel is held (soaked) at this
temperature 2.5 minutes 25 mm thickness and then is rapidly cooled in water or brine.
 A graph of maximum hardness versus carbon content
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ENGINEERING MATERIALS
Tempering: The steel obtaining after hardening is brittle and unsuitable for most uses. So another
operation know as tempering is required to be applied in order to reduce hardness brittleness.
 Tempering is define as reheating below the critical temperature (A1) and cooling takes place
at room temperature.
 Such reheating permits the trapped marten site to transform and relive the internal stresses.
The temperature is determined by the specification of steel and the final hardness and
toughness desired.
Purpose:
 To reduce hardness, brittleness and tensile strength.
 To increase ductility and toughness.
 To relive quenching stresses.
 To equalize the hardness in piece as far as possible.
 According to the usefulness of steel the tempering is divided in to three classes.
 Low temperature tempering.
 Medium temperature tempering
 High temperature tempering
Surface hardening:Surface hardening is defined as a process for hardening a ferrous material in such a way that
the surface layer known as case is substantially harder than remaining material known as core.
Surface hardening involves the hardening of the surface without changing the chemical composition
at the surface of steel.
Depending upon the method of heating surface hardening is of two types
a) Flame hardening
b) Induction hardening
 (a)Flame hardening:-It is the treatment process in which surface of steel is heated rapidly
above the transformation temperature by a high temperature flame and quenched to produce
marten site. In flame hardening oxyacetylene flame is used which can generate temperature
upto 3000°c.
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ENGINEERING MATERIALS
 (b)Induction hardening: it is defined as heating the medium carbon steel by means of
alternating magnetic field to a temperature above transformation range (750°-800°c) followed
immediately by quenching.
The work piece can be heated by electromagnetic induction by passing an alternative current
through an inductor ,piston rod, pump soft spur gear, crankshaft and hardened by this method.
Age hardening:
When aluminumalloy containing about 4% copper is heated to a temperature and quenched
in water,its hardness increase with time on keeping the alloy at room temperature. This phenomenon
is called age hardening.
Process:
The two phase at room temperature is greeted to a temperature at which homogeneous
single phase solid solution is obtained .the alloy is held at this temperature for homogenization. The
holding time vary from 30 minute to several hours.
After obtaining the homogeneous solid solution the alloy is cooled rapidly by water.
After quenching the alloy is a held at a particular temperature for some time.
Process: the steel is heated to austenizing temperature and it is then quenched in a medium. The
particle is held in the both until it reached the temperature of medium is held in the both until it
reached the temperature in air. Sometimes cooling takes place in oil austenite I transferred in to
marten site during the cooling period at room temperature.
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ENGINEERING MATERIALS
4TH CHAPTER
CRYSTAL IMPERFECTIONS
2 Marks
Q.1Define imperfection in crystal?
Ans: Imperfection in crystal is produced due to the misalignment of atoms, vacant of atom, distortion
of lattice etc.in the metal structure.
Q.2 Classify crystal imperfection?
Ans:Crystal imperfection is classified in to
 Point defect-vacancies, interstialicies, impurities, electronic defects.
 Line defect-edge dislocation, screw dislocation
 Surface defect- grain boundaries tilt boundaries,twin boundaries
 .Volume defect:cracks.
Q.3. What is deformation by slip?
 Ans: Slip is that mechanism of deformation where in part of crystal moves,glides or slips over
another part along certain planes knownas slip planes .
 Deformation by slip is also known as shear deformation
Q.4. What is screw dislocation?
 Ans:-Screw dislocation is a line defect which can be described as a linear disturbance of the
atomic arrangement of a crystal where in a part plane of atoms is shifted from its stable and
symmetrical position in the crystal.
 A screw dislocation lies parallel to its burger s vector. In screw dislocation the distortion
follows a helical or screw path.
Q.5.What is imperfection in crystal?
Ans: Imperfection in crystal is produced due to the misalignment of atoms,vacant of atoms distortion
of lattice .in the metal structure.
Q.6.What is schottky defect?
Ans: This is an ionic defect in which a cat ion and an anion are missing from a location so that
electrical neutrality is maintained.
5 MARKS
Q.1. State various causes of dislocation?
Ans: Dislocation arise in crystal as a result of
 Growth accidents
 Thermal stresses
 External stresses causing plastic flow
 Phase transformations
 Segregation of solute atoms causing mismatches etc.
Q.2. State the various causes of dislocation?

Dislocation arise in a crystal as a result of
 Growth accidents
 Thermal stresses
 External stresses causing plastic flow
 Phase transformations
 Segregation of solute atoms causing mismatches etc.
 steel is heated to 20°c above lower temperature.
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ENGINEERING MATERIALS
Q.3.Explain the cooling curve of pure iron?
Ans: The crystal imperfection less be grouped in to the following categories depending upon whether
the defect is at a point,along a line or over a surface. All defects are classified under three main
groups.
 Point defects
 Vacancies
 Interstialicies
 Impurities
 Electronic defect
 Line defects;
 Edge dislocation
 Screw dislocation
 Planner surface,interfacial or grain boundaries defects
 Grain boundaries

Tilt boundaries,
 Twin boundaries.
 Volume defects
7 MARKS QUSTIONS WITH ANSWERS
Q.1.Explain properties changes by deformation?
 Ans: Working hardening: Work hardening or strain hardening is a phenomenon which results
in an increase in hardness and strength of metal subjected to plastic deformation at
temperatures lower than the recrystallization range.
 Season cracking: In addition to the change in physical and chemical properties,internal
stresses, often of very high intensity may be left in an object after cold deformation.
 Metal such as brass with internal stresses appearing after working is susceptible to inter
crystalline corrosion.If it is stored for a long period. This leads to disintegration or failure of the
metal. This phenomenon is called season cracking.
Strain ageing:
 If an alloy is overstrained in order to re move the yield point and is allowed to rest after plastic
deformation it is found that the yield point returns with a higher stress when the alloy is
reworked. This is called strain ageing and has a hardening effect on the metal.
 Preferred orientation: It has been seen in the foregoing articles that the grain of a
polycrystalline material have random orientation .in cold working specially in those processes
where severe plastic deformation takes place e.g. in cold rolling or wire drawing the metal
grains tend to orient or align themselves in such a manner that they possess a common axial
direction
Q.2.What is line defect?
Ans: The main two dimension or line defects are dis location.
 A dislocation can be described as a liner distribution of the atomic arrangement of
crystal wherein a part-plane of atoms is shifted fromits stable and symmetrical position
in the crystal.
 It can be conceived as a region of localized lattice disturbance which separates of
localized lattice disturbances which separates the slipped region of the crystal from its
unslipped region.

The plastic deformation of metal due to slip phenomenon is mainly on account of dislocations
only.
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ENGINEERING MATERIALS


The two main types of dislocations are
Edge dislocation
Screw dislocation.
Q.2. Explain the different types of line defects?
Ans: Edge dislocation
 An edge dislocation lies perpendicular to its burgers vector.
 An edge dislocation moves in the direction of burger s vector.
 An edge dislocation involves an extra row atoms either above or below the slip plane. The
presence of extra row means that adjacent atoms are displaced elastically.
 Under a shear stress positive dislocation moves to the right and negative dislocation to the
left.
 The edge dislocation is particularly useful in explaining slip in plastic flow during mechanical
working.
Screw dislocation:



A screw dislocation lies parallel to its burgers vector.
A screw dislocation moves in a direction perpendicular to the burgers vector.
In the screw dislocation the dislocation follows a helical path or screw path and both right
hand left hand senses are possible.


Speed of movement of screw dislocation is less than that edge dislocation.
Screw dislocation is especially useful in explaining crystal growth as well as slip in plastic
deformation .
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ENGINEERING MATERIALS
Q.3 Describe different types of point defects?
Ans(a)If the imperfection takes place in point like regions in the crystal then it is called point defect or
point imperfection. It is also referred as zero dimension imperfection.
Various types of point defect are as described below.
 Vacancies: It is a simplest point defect.Vacancies are simply empty atom sites.
Causes: such defect may arise either from imperfect packing during the original crystallization.
They may arise from thermal vibration atoms at high temperature, because as the thermal energy is
increased there is a higher probability that individual atoms with jump out of their position of lower
energy.
 Number of vacancies may occur by extensive plastic deformation(cold working)
Vacancies maybe single, or two or more.
 Schottky effect is closely related to vacancies and is formed when an ion is removed from a
normal lattice site and replaced in an average position on the surfaceof crystal.
 Interstitialcies:
An interstitial defect arise when an atom occupies a definite position in lattice that is no.s occupied in
perfect crystal.
 In interstitalcies atoms occupied between atoms of ideal crystal.
The interstitial atom may be lodged with in a crystal structure ,particular if the atomic packing factor is
low.
Interstitalies may be single interstitial, di- interstitial and tri –intersticies.
 The vacancy and interstitials are therefore inverse phenomena.
Frankel defect is closed relatedto interstialcies. An ion displaced from the lattice in to an interstitial site
is called frankel defect.
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ENGINEERING MATERIALS
Impurities:
It gives rise to compositional defect.
 Impurity atoms are introduced in to crystal structure as substitution or interstitial
atoms.
 Impurity defects occurs in metallic covalent and ionic solid.
Electronic defect:Due to electronic defect charge distribution takes place in solids. This effect is
responsible for operation of P-n junctions and transistors.
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ENGINEERING MATERIALS
5THCHAPTER
HEAT TREATMENT
2 MARKS
Q.1.What is heat treatment?
Ans: It is an operation or combination of operations involving heating and cooling of a metal/alloy in
solid state to obtain desirable properties and conditions.
Q.2What is hardening?
Ans: Hardening is define as the heat treating process in which the material is heated to a temperature
within or above its critical temperature and held at this temperature for a considerable time to ensure
proper penetration of the temperature inside the component and allowed to cool by quenching in
water, oil or brine solution.
Q.3What is tempering?

Ans:- It is the process of reheating a quench hardened steel to reduce its inter stress and to
increase its toughness.

Re-heating is done to a temperature varying from 250°c to 650°c .Depending upon the
reheating temperature the process is called low temperature tempering medium temperature
tempering or high temperature tempering.
Q.4 Name the different type of quenching media for hardening of steel?
Ans: Different type of quenching media for hardening of steel are air, oil,solution of special
component(sodium hydroxide and sulphuric acid and water) water,brine.
Q.5. Define Mar tempering?
Ans:-Mar tempering is define as heating the steel to austenite temperature and is quenched in a liquid
bath having high temperature and again it is transferred to a bath having low temperature.

Improve ductility

Improves mechanical properties

Improves strength and toughness
Q.6.What is normalizing?
Ans: It is defined as the process of heating the steel 40° to 50°above the upper transformation
range,holding there for a specific period and then allowing it to cool in still air at room temperature
Q.7.What is heat treatment?
Ans: it is an operation or combination of operations involving heating and cooling of a metal/alloy in
solid state to obtain desirable properties and conditions.
Page 18
ENGINEERING MATERIALS
5 MARKS
Q.1 Defineannealing?
Ans: Annealing is defined as a softening process consisting of heating the steel to a temperature at or
near the critical point,holding there for a proper time and then allowing it to cool slowly in the furnace
itself. The temperature required for annealing varies with different steels.low carbon steels are heated
to a temperature slightly above the upper critical temperature high carbon steels having more than
0.9% carbon are heated to a temperature within the critical range. High carbon steels are heated to a
temperature below their critical point .hypereutectoid steel is heated to 20°c above the upper critical
temperature, while hypereutectoid steel is heated to 20°c above the lower critical temperature.
Q.2 Define hardening?
Ans: Hardening is define as sheeting the steel to a temperature within or above its critical temperature
and held at this temperature for a considerable timeto ensure proper penetration of the temperature
inside the component and then allowed to cool by quenching in water,oilor brine solution.
Q.3.What is hardening? What are the purposes of hardening?
Hardening is define as heating the steel to a temperature within or above its critical temperature and
hold at this temperature for a considerable time to ensure proper penetration of the temperature inside
the component and then allowed to cool by quenching in water,oil or brine solution.
The purposes of hardening is to

Improve strength and toughness.

Improve ductility.

To develop hardness and wear resistance properties.

To develop mechanical properties.
7 MARKS
Q.1 Explain the purpose of heat treatment?
Ans: To improve strain hardening of cold worked metal piece and improve its ductility.
 To improvegases from casting.
 To soften a metal to improve its machinability.
 To improve resistance against wear, heat and corrosion.
 To improve the cutting ability i.e. to improve hardness of a toolsteel.
 To restore electrical conductivity of cold worked metal
 To improve magnetization properties, especially of steels, for producing permanent magnets.
 To refine grain structure after hot working a metal
 To produce a hard, wear resistance case on a tough core of a steel.
 To soften and toughness a higher a high carbon steel piece
 To harden non-ferrous alloy and metals,especially aluminum alloys.
 To toughen a hardened steel piece at alow cost of its hardness
 To remove effects of previously performed heat treatment operations.
 To relive inter stresses set up by un equal contraction in castings.
Page 19
ENGINEERING MATERIALS
Q.2 List the effect of heat treatment of properties of steel?

Steel are used for varied purpose engineering industry and thus they required different
properties according tom the field of application.

The properties of plain carbon steel can be by heating and cooling them under definite
condition making them suitable for specific application.

The properties of plain carbon steels have relation with the type of heat treatment the
subjected to various heat treatment processes annealing,hardening,and tempering etc. affix
properties of plain carbon steels as described below
Annealing:

Homogenizes the structure

Reduce hardness

Improves machinability

Hardening followed by tempering:

Hardens steel to resist wear

Enables steel to cut other metals

Improves strength ,toughness
Normalizing:

Produces a uniform structure

Refine grain size

Reduces internal stresses

Case hardening processes:

Increase the surface hardness of low carbon steel

Provide a wear resistant case and a relatively soft,tough,and shock resistant core.
Q.3 Describe the method of annealing?
o
Ans:-Annealing:- It is define as a softening process consisting of heating the steel to a
temperature at or near the critical point,holding there for a proper time and allowing it to cool
slowly annealing varies with different steels.
o
Low carbon steels are heated to a temperature slightly above the upper critical temperature
high carbon steels having more than 0.9% carbon are heated to a temperature within the
critical range. High carbon steel is heated to a temperature below their critical point.
Hypoeutectoid steel is heated to 20°c above the upper critical temperature, while hyper
eutectoid
o
Purposes of hardening. If consists of heating steel to a temperature a little below the critical
range(A1) and then cooling it slowly. It is applied to remove the effect of cold wok, to soften
and permit further cold work as in sheet and wire industries.
o
Ferrous alloys are heated to a temperature closed to but below, the lower limit of the
transformation range (550-650°c) are held at that temperature and then cooled usually in air
in order to soften the alloy for further cold working as in wire drawing.
Page 20
ENGINEERING MATERIALS
o
Process annealing associates with it only partial recrystallization of the distorted ferrite and
since mild steel contains only a small volume ofstraine4d pearlite, a high degree of soften is
induced.
o
)
Process annealing doesnot involve any phase change and the constituent ferrite and
cementite remain present in the structure thought out the process.
o
Full annealing:
o
The definition of annealing describes the full annealing that it consists heating the steel to a
temperature at or near the critical point ,holding there for a proper time and then allowing it to
cool slowly in the furnace itself.
o
The austenitizing temperature for hypo eutectoid steel is usually between 723°c (133°F) and
910°c(1670°F) and for hyper eutectoid steels,austenitizing temperature is between 723°c
(1333°c) and 1130°c(2066°F)
Refine grains
o
Removes strains(from forging and castings)
o
Improves machinability
o
Improves formality
o
Improves electrical and magnetic properties.
Q.4.Describes various heat treatment processes and elaborate the annealing and tempering?
Ans:
Heat treatment is define as an operation of heating of solid metal to specified temperatures
holding them at that temperature and then cooling them at suitable rates in order to enable the metal
to acquire the desired properties
Page 21
ENGINEERING MATERIALS
The following heat treatment processes are:
1.annealing
2.normailising
3.tempering
4.spheroidising
5.hardening
6.case hardening
7.age hardening
8.induction hardening
9.flame hardening
10.cryniding
11.nitriding
1.Annealing:
Annealing is define as a soften process consisting of heat in the steel to a temperature at or
near the critical point,holding there for a proper time and then allowing it to cool slowly in the
furnace itself.
The temperature required for annealing varies with different steels .low carbon steels are
heated to a temperature slightly above the upper critical temperature high carbon steels
having more than 0.9% carbon are heated to a temperature within the critical range.
High carbon steels are heated to a temperature below their point. Hypoeutectoid steel is
heated to 20°c above the upper critical temperature, while hypoeutectoid steel is heated to
20°c above the lower critical temperature.
Objects of annealing:
To soften the metal
To improve machinability
To improve mechanical properties like ductility
To refine grainsize.
To relive internal stresses.
To remove gases to produce a definite micro structure
To minimize segregation of essential constituent of the steel
To modify electrical and magnetic properties.
To prepare steel for subsequent heat treatment
Types of annealing treatment: It consists of heating the steel to a temperature a little below the critical
range (A1) and then cooling it slowly.it is applied to remove the effects of cold workto soften and
permit further cold work as in sheet and wire industries.
Ferrous alloys are heated to a temperature close to but below,the lower limit of the
transformation range (550-650°c) are held at that temperature and then cooled usually in air
in order to soften the alloy for further cold working as in wire drawing.
Process annealing associates with it only partial recrystallization of the distorted ferrite and
since mild steel contains only a small volume of strained pearlite,a high degree of softening is
Page 22
ENGINEERING MATERIALS
induced.process annealing doesnot involve any phase change and the constituents ferrite
and cementite remain present in the structure throughout the process.
Full annealing: The definition of annealing describes the full annealing that is it consist of
heating the steel to a temperature at or near the critical point,holding there for a proper time
and then allowing it to cool slowly In the furnace itself.
The austenitizing temperature for hypoeutectoid steel is usually between 723°c(133°F) and 910°c
(1670 F) and for hyper eutectoid –tool steels,austenitizing temperature is between
(i)Re fine grains
(ii)Removes strains (from forgings and casting)
(iii)Improves machinability
(iv)Improves formability
(v)Improves electrical and magnetic properties.
Normalizing:Normalizing or air quenching consist in heat in steel to about 40-50°c above its upper
criticaltemperature (i.e. .Aᴈand Am line) and if necessary,holding it at that temperature for a short time
and then cooling in steel air at room temperature normalizing differs from full annealing in that the rate
of cooling is more repaid and there is no extended soaking period.
The type of structure obtained by normalizing will depend largely on the thickness of cross
section as this will affect the rate of cooling. Thin section will give a much finer grain than thick
sections.
Normalizing produced microstructures consisting of ferrite (white network) and pearlite (dark
areas) for hypo eutectoid (i.e. up to about 0.8% c) steels.
Normalizing(purpose)
Produces a uniform structure
Refine the grain size of steel, which may have been unduly coarsened at the forging or rolling
temperature.
May achieve the required strength and ductility in a steel that is too soft and ductile for
machining.
Reduces internal in welds.
Improves structures in welds.
Producea harder and stronger steel than full annealing.
Eliminates the carbide netword at the grain boundaries of hypereutectoid steels.
In general improves engineering properties of steel
Hardening:
Hardening is define as heating the steel to a temperature within or above its critical temperature and
hold at this temperature for a considerable time to ensure proper penetration of the temperature inside
the component and then allowed to cool by quenching in water, oil or brine solution.
If the carbon content ofsteel is known, the propertemperature to which the steel should be
heated may obtained by the iron-carbon equilibrium diagram.
Page 23
ENGINEERING MATERIALS
Purpose:
Improves strength and toughness
Improve ductility
To develop harness and wear resistance properties.
To develop mechanical properties.
Process: The steel is heated to a temperature of 790-850°c.the steel is held at this temperature 2.5
minutes 25 mm thickness and then is rapidly cooled in water or brine.
A graph of maximum hardness versus carbon content
Tempering:
The steel obtaining after hardening is brittle and unsuitable for most uses. So another operation
known as tempering is required to be applied in order to reduce hardness brittleness.

Tempering is define as reheating the previously hardened steel to a temperature below the
critical temperature (A1) and cooling takes place at room temperature.
Such reheating permits the trapped marten site to transform and relieve the internal stresses. The
tempering temperature is determined by the specification of steel and final hardness and toughness
desired.
Purpose:

To reduce hardness,brittleness and tensile strength.

To increase ductility and toughness.

To relive quenching stresses.

To equalize the hardness in a piece ,as far as possible
According to usefulness of steel the tempering is divided in to three classes

Low temperature tempering

Medium tempering

High temperature tempering
Mar tempering:
Mar tempering is define as heating the steel to austenite temperature and is quenched in a
liquid bath having high temperature and again it is transferred to bath having low temperature.
Page 24
ENGINEERING MATERIALS
Purpose:

Improve ductility

Improve mechanical properties

Improve strength and toughness
Surface hardening:

Surface hardening is define as a process for hardening a ferrous material in such a way that
the surface layer known as case, is substantially harden than remaining material known as
core.surface hardening involves without changing the chemical composition at the surface of
steel.
Depending upon the method of heat in surface hardening is of two types

Flame hardening

Induction hardening
(a)Flame hardening: It is the heat treatment process in which surface of steel is heated rapidly above
the transformation temperature by a high temperature flame and quenched to produces marten site.

In flame hardening oxyacetylene flame is used which can generate temperature up
to 3000°c.
(b)Induction hardening: it is define as heating the medium carbon steel by means of
alternatingfield to a temperature above transformation range (750°-800°c) followed
immediately by quenching .the work piece can be heated by electromagnetic induction by
passing an alternative current through an inductor,piston rod, pump shaft spur gear,
crankshaft are hardened by this method.
Page 25
ENGINEERING MATERIALS

Age hardening:
When aluminum alloy containing about 4% copper is heated to a temperature and quenched in
water,its hardness increase with time on keeping the alloy at room temperature. This phenomenon is
called age hardening.
Process:
The two phase alloy at room temperature is heated to a temperature at which homogeneous
single phase solid solution is obtained.the alloy is held at this temperature for homogenization. The
holding time may vary from 30 minute to several hours.
After obtaining the homogeneous solid solution the alloy is cooled rapidly by water.
After quenching ,the alloy is aged at particular temperature for some time.

Process: The steel is heated to austenizing temperature, it is quenched in a medium
.the particle is held in the both until it reaches the temperature of medium and then it
is cooled further to a temperature in air. Sometimes cooling takes place in
oil.austenite is transferred in to room temperature.
Q.5.Notes onNormalizing and Mar tempering.
Ans: Normalizing:
Normalizing or air quenching consist in heat in steel to about 40-50°c above its upper
critical temperature (i.e.Aᴈand Am line) and necessary, holding it at that temperature
for a short time and then cooling in steel air at room temperature normalizing differs
from full annealing in that the rate of cooling is more rapid and there is no extended
soaking period.

The type of structure obtained by normalizing will depend large on the thickness of
cross section as this will affect the rate of cooling .thin section will give a much finer
grain than thick section.

Normalizing produces micro structure consisting of ferrite(white network) and
pearlite(dark areas) for hypo eutectoid(i.e. up to about 0.8% c )steel.
Purposes of normalizing:

Produce a uniform structure,

Refine the grain size of steel which may have been un duly coarsened at the forging or rolling
temperature.

May achieve the required strength and ductility in a steel that is too soft and ductile for
machining.
reduce internal in welds.

Improves structures in welds.

Produces a harder and stronger steel than full annealing.

Eliminates the carbide netword at the grain boundaries of hypereutectoid steel.

In general ,improves engineering properties of steels.
Page 26
ENGINEERING MATERIALS
Mar tempering:

It is also known as stepped punching and employee producing marten site.
In is also known as stepped punching process and employee for producing marten site.
In this type of tempering processthe steel is heated above the transformation range and then
suddenly quenched In a molten salt bath at a temperature 180 to 300°c. it is held at this temperature
until the cone and outside temperature are eqalised.it is then removed from the bath and allowed to
cool at moderate rate.

The holding time in the quenching bath-should be sufficient to enable an uniform temperature
to be reached throughout the cross-section last not long enough to cause austenitic
decomposition. Austenite is transformed in to marten site during the subsequent period of
cooling to room temperature .The main purpose of mar tempering is to minimize
distortion,cracking and internal stresses that result from normal quenching in oil or water.
Advantage of mar tempering:

Less distortion or warping

Less change in volume

Less change at quenching cracks and internal stresses.
Q.6. Explain different types of surface hardening method?
Ans:-Surface hardening:

It is define as a process for hardening a ferrous material in such a way that the surface layer
known as case, is substantially harder than remaining material known as core. Surface
hardening involve the hardening of the surface without changing the chemical composition at
the surface of steel.

Depending upon the method of heating surface hardening is of two types

Flame hardening

Induction hardening.
Flame hardening: It is the heating treatment process in which surface of steel is heated rapidly above
the transformation temperature by a high temperature flame and quenching to produce marten site. In
flame hardening oxyacetylene flame is used which can generate temperature up to 3000°c.
Page 27
ENGINEERING MATERIALS
Induction hardening:
It is define as heating the medium carbon steel by means of alternation magnetic field to a
temperature above transformation range (750°-800°c)followed immediately by quenching.
The work piece can be heated by electromagnetic induction by passing an alternative current through
an inductor ,piston rod, pump soft spur gear, crankshaft and hardened by method.
Q.7 Write the composition properties and uses of Y-alloy?
Ans: Composition
Copper=3.5-4.5%
Manganese=1.2-1.7%
Nickel=1.8-2.3%
Silicon,magnesium,iron=0.6% each and the remaining is aluminum.
Properties:

It is good at high temperature

It is non-magnetic.

It is good conductor of heat.

It is very ductile.
Use:

Transportation industry –structure flame- work ,engine parts, trim and decorative
features,hardware,doors,window frames,tanks,furnishing and fittings.

Train ,truck,buses, automobile cars and aeroplanes use many component part made up
aluminum alloys.

Overhead conductors and heat exchanger parts.

In food industry,aluminum alloys find application as food preparation equipment
(pianistic),refrigeration,storage containers,bakery equipment, shipping containers, etc.

Mangles and wafflemolds.
Q.8 List effect of heating treatment on properties of steel?
Ans: Steels are used for varied purpose in engineering industry and thus they required different
properties according to the field of application.

The properties of plain carbon steels can be altered by heating and cooling them under
definite conditions to make suitable for specific applications.
Page 28
ENGINEERING MATERIALS

The properties of plain carbon steels have definite relation with the type of heat-treatment
they are subjected to various heat treatment processes such as annealing,hardening and
tempering etc. affect the properties of plain carbon steels as described below.
Annealing:

Homogenizes the structure.

Reduces hardness.

Improves machinability.

Hardening followed by tempering.

Hardens steel to resist wear.

Enable steel to cut other metals.

Improves strength ,toughness and ductility.
Normalizing

Produces a uniform structure

Refine grain size.

Reduces internal stresses.

Case hardening processes.
(i)Increase the surface hardness of low carbon steels.
(ii)Provide a wear resistant case(outer surface) and a relatively soft ,tough and shock
resistant core (inside of the component).
6TH CHAPTER
NON-FERROUS ALLOYS
2 Marks
Q.1.Write the composition of duralumin?
Ans: It consists of Al=95%,Cu=4%,Mn=0.5%.Mg=0.5%.
Q.2. Write the composition of Babbitt’s metal?
Ans: Lead or tin based alloys are called Babbitt’s metal.
Composition:
Lead base alloy=Pb=75%,sb=15%,sn=10%
Tin base alloy=Sn=88%,Sb=*%,Cu=4%
Q.3.What is the composition of brass?
Ans:-
Cu=60-90%,
Zn=40-10%,
Q.4. Give the composition of Duralumin?
Ans.- Cu=3.5-4.5%
Mn=0.4-0.7%
Mg=0.4-0.7%
Fe or Si<0.7%
Al=rest.
Page 29
ENGINEERING MATERIALS
Q.5. Name any fur metal used for nuclear energy?
Ans: Metal used for nuclear energy are

Uranium

Plutonium

Thorium

Zirconium

Beryllium

Niobium
5 MARKS
Q.1. Name the alloys used for high temperature service?
Ans:Duralumin: It contains
Cu
3.5-4.5%
Fe or Si <0.7%
Mn
0.4-0.7%
Al
Mg
Balance
0.4-0.7
Q.2.Describe composition properties and application of zn alloys?
Ans:Zinc and zinc based alloys

Zinc is a blue to gray metallic element.

Zinc has following characteristics.

Relatively low melting point.419.5°c(die casting)

Good resistance to atmospheric corrosion.

Solubility in copper(brass)

Inherent ductility and malleability.
7 MARKS
Q.1Describe the composition, properties and use ofaluminum alloys such as duralumin, yalloy?
Ans:Types of aluminum alloys

Aluminum alloys contain
 Al-Mn
 Al-Mg
 Al-Mg-Mn
 Al-Mg-Si
Page 30
ENGINEERING MATERIALS
 Al-Cu-Mg
 Al-Cu-Si
 Al-Cu-M-Pb
 Al-Mg-Si-Pb
 Al-Zn-Mg-Cu

Aluminum alloys can be classified as follows.
 Wrought alloys
 Cast alloys
 Heat treatment alloys
 Non heat treatment alloys
Percent compositions of few wrought alloys are

4.4 Cu

,0.6Mn,

1.5Mg,Balance Al.

0.12 Cu,

1.2 Mn,

Balance Al.

2.5 Mg

,0.25Cr

,Balance Al

0.6Si,0

.27Cu,

Mg,

0.2 Cr,

balance Al
Percent composition of few cast alloys are

12 Si,rest Al

4 Cu,

3Si

,rest Al

4.5Cu,

5.5Si,

rest Al

3.8Mg,

1.8Zn

.rest Al
Page 31
ENGINEERING MATERIALS
Percent composition of few heat treatment alloys are

3.9-5.0 CU,

0.2-0.8 Mg,

0.5-1.0 Si, 0.5-1.2Mn,

rest Al

0.5-1.2

Mg,0.7-1.3 Si,

0.4-1.0 Mn,

rest Al

0.4-0.9 Mg

,0.3-0.7 Si

, rest Al
Percent composition of few non heat treatable alloys are

0.8-1.5 Mn ,

rest Al

1.7-2.4Mg

,rest Al

10-13% Si,

rest Al

5.0-5.5Mg,

0.6-1.0Mn,

0.05-0.20 Cr,

rest Al
For duralumin:it contains

Cu
3.5-4.5%

Mn
0.4-0.7%

Mg 0.4-0.7%
Fe or Si <0.7%
Al
balance
Duralumin possesses:
*High machinability.
*High tensile strength after heat treatment
*Strength as high as steel but has only about 1/3 of its weight
*Excellent casting and forging properties
Duralumin finds the following uses:
*Aircraft and automobile part.
*As bars,sheets,tubes,and rivets
*As light structures and extruded sections
For Y-alloy:
Copper=3.5-4.5%
Page 32
ENGINEERING MATERIALS
Manganese=1.2-1.7%
Nickel=1.8-2.3%
Silicon,magnesium iron =0.6% each the remaining is aluminum.
Q.2.Describe compositionproperties,and application of zinc alloys?
Ans: Composition:Rolled zinc:
Pb=0.05 to 0.12
Fe=0.012 to max
Cd=0.005 to max
Cu=0.65 to 1.25
Zn=remainder
High grade slab zinc:
Pb=0.07, Fe=0.02, Cd=0.07(Pb+ Cd+ Fe)=>Zn=Remainder
Selected grade slab zinc:
Pb=0.08,Fe=0.04,Cd=0.75(Pb+ Cd=Fe)>1.26Zn-remainder
Properties:

Zinc is a blue to gray metallic element

Relatively low melting point

Good resistance to atmospheric corrosion

Solubility in copper

Inherent ductility and malleability

Thermal conductivity
Application:

Stampings

Die casting

Anodes for electro-galvanizing

Coating on steel

Making different alloys

Fabricated and rolled shapes

Shells for dry batteries

Building material

Engravers plates

Wire for metalizing

Lithographers sheets
Page 33
ENGINEERING MATERIALS
Q.3.Explain the lead alloys with composition properties and uses?
Ans: Lead –antimony alloy
Composition:Antimony 6to 8 lead-rest.
Properties:
(i)It has highly resistance to sulphuric acid.
(ii)High tensile strength of about 470kg/cm²
(iii)High elongation of 22%
Uses: Storage-battery plates
Cablesheeting
Collapsible
Lead-tin alloy
Type metal composition: Pb=75%,Sb=20%,Sn=5%
Properties:It gives good casting.
Uses: It is used for producing printer type.
Soft solder
o
Composition:Pb=37-67%,Sb=31-60%,Sn=0.12-0%
They melt at low temperature and uses for soldering electrical connection and joining lead pipers.
Wood s metal
o
Composition:Bi=50%,pb=25%,Sn=12.5%,cd=12.5%
It is read by fusible (m.pt-70°) and used for making fire-alarm, shaft plugs for cookers,milk pot,boiler
and selective fuses etc.
Q.4.Write the composition and application of muntz and phosphor bronze?
Ans: Muntz metal:

Composition:Cu=60%,Zn=40%
o
Application: Application of muntz metal are as:
o
Slip heating
o
Valve stems
o
Architectural work etc.
o
Perforated metal
o
Condenser tubes
o
Phosphor bronze
o
Low –phosphorus bronzer

Composition: Cu=rest,Sn=0.7%,P=upto 0.4%
Application:
o
_ Spindles for valves and pumps
o
-Boiler fitting and sheets
o
-Bearing plates
o
High phosphorus bronze;

Composition :Cu=rest.Sn=10-13%,P=0.4 to1%
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ENGINEERING MATERIALS
Application: It is used for making
o
Bearing and gears
o
Taps,bushes
o
Spring
o
Turbine blades
o
Fibers for moving coil galvanometer, fuses etc.
Q.5.Describe various types of surface hardening method?
Ans: Induction hardening:
The purpose of induction or flame hardening is to obtain hard and wear resistance surface whilst the
cone remains soft,the processes of induction hardening and flame hardening direr from each other in
the way of heating.

In process of induction hardening a high frequency current of about 1000 to 10,000 cycles per
second is passed through a copper inductor block which acts as a primary coil of the
transformer heating by high frequency current is accomplished by thermal effect of the current
induced in the article being heated. The latter is placed in an alternating magnetic field set by
the high frequency current.the part to be heated or several turns ofcopper tube or bus bar.
When alternating current is passed through turns of copper tube or bus bar.when alternating
current is passed through the inductor,it sets up a magnetic field the intensity of which varies
periodically in magnitude and direction.the alternating magnetic line pass through face of
article being heated in the inductor and induce the surface an alternating current of same
frequency but reversed in direction.this alternating current produces heating effect on the
surface and temperature produce is of the orderof 750 to 800°c for plain carbon and alloy
steel. The heating areas are then quenched immediately by sprays of water delivered through
numerous small holes in the inductor block.the part should have carbon content of about
0.75% for this method.

The induction hardening is at present extensive used for producing hard-surfaces on crackshafts, car shaft,axles and gears.
Advantage:
o
The time required for this heat-treatment operation is less thereby increasing the labor
productivity.
o
Deformation due to heat treatment is considerable reduces.
o
The article which are induction heated have no scale effort.
o
The hardening of the surface can be easily controlled by controlling the current.
o
The depth of hardness can be easily controlled by varying the frequency of supply voltage.
Flame hardening:
Any carbon steel carrying above 0.3% carbon can be surface hardened by method.
o
In flame hardening a high intensity of oxy-acetylene flame is used to heat the surface or area
to be hardened to above its critical range, so that austenite is formed ,and then the hot
surface is quenched to attain the desired hardness.
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ENGINEERING MATERIALS
o
This may be followed by tempering if required because of the flame the heating is varyquick
and is confined only to the surface and is localized to only a limited area. Also,the water
spray(quenchy) immediately follows the flame.
o
These two factors lead to a very slow and limited heat transfer to remaining part of the
component,leaving the lattice free of any appreciable change.depending upon the type of
steel,if air quenching is required,a compressed air jet may replace the water spray.
o
Also if the desired surface properties required tempering after flame hardening a low
temperature flame follows the quenching spray to reheat the surface to tempering
temperature,followed by tempering quench.
o
This process is quite flexible because the rate and depth of heating both can be varied
according to the requirement.the process can be performed manually or can be made fully
automatic.,inducing computer controlled.
Laser beam hardening:

This process is also used for surface hardening of medium carbon and high carbon steels. In
this process the job surface to be harden is first coated with an absorptive media as zinc or
manganese phosphate, a laser beam is then used and the coated surface is scanned with it .

The beam size,the scanning speed and the intensity of beam are chosen according to the
results desired. The absorptive coating applied on the surface helps in accelerating the
conversion of light energy in to heat.soon after the scanning is over it isfollowed by water
quenching or oil quenching.

Since there is no addition of carbon from outside the degree of hardness attained by the
surface will mainly depend upon carbon content of material. The main advantage hardening,
almost negligible distortion can be fully automatic and even computer controlled.
Electron beam hardening:
o
Its application is limited to only smaller and medium size components because of constraints
imposed by the size of the vacuum chamber in which the component if to be housed
o
In operation the process is almost similar to laser beam process except that here a high
energy electron beam replaces the laser beam as a heating surface.
o
Electromagnetic controls are employed for directing and focusing the charged electrons on to
the surface to be hardened.the component is enclosed in a high vacuum chamber and has to
be manipulated in vacuum only.
o
It is essential because the electron cannot travel in the directed path in air.
o
This process can be easily automated.
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ENGINEERING MATERIALS
7TH CHAPTER
BEARING MATERIAL
2MARKS
Q.1.Write the composition of lead base bearing metal?
Ans: Composition
Pb=75%
Sb=15%,
Sn=10%
Q.2. Write down four properties of bearing material?
Ans: Properties:
o
Possess low co-efficient of friction.
o
Provide hard,wear resistant surface with a tough core.
o
Have high compressive strength
o
Be able to bear shocks and vibration.
5 MARKS
Q.1.Write any four desirable properties of bearing material?
Ans: Properties of bearing material.

A bearing material

Possess low co-efficient of friction

Provide hard ,wear resistance surface with a tough core.

Have high compressive strength

Have high fatigue strength

Be able to bear shocks and vibration.
Q.2.Classify bearing materials?
Ans-Bearing metals are
o
Lead or metals are
Example – White metal,Babbitt’s metal
o
(ii) Cadmium –based alloys .
Ex: Automobiles and air craft industries
o
(iii) Aluminum –based alloys
Example –Bearing is diesel engines and tractors.
o
(iv) Silver-based alloys
Examples:-Connecting rod bearing of air craft engine.
o
(v) Copper- based alloys
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ENGINEERING MATERIALS
Examples:-Bronze,bearing in railway.
o
(vi)Sintered bearing materials-
Examples:-sintering iron bearing .
o
(vii)Non metallic bearing materials-
Examples:-Teflon and nylon.
7 MARKS
Q.1. Write the composition ,properties and uses of copper base bearing?
Ans:Copper based bearing metal:
Composition:typical composition of bearing bronze are;
I
II
Cu
80%
85%
Sn
10%
15%
Pb
10%
-

The term bronze covers a large number of copper alloy with varying percentages of
sb,znand pb. bronze is done of oldest known bearing materials.
Bronze:

It is easily worked.

It has good corrosion resistance and

It is reasonably hard.
 Tin bronze (10 to 24% tin, remainder copper) is used in the machine and engine industry for
bearing bushes made from thin walled drawn tubes.
Copper based alloys are employed for making bearings required to resist behavior pressures such as
in railways.
Q.2.Describe the composition,properties and use of copper base bearing metal and tin base
bearing metal?
Ans:Copper based bearing metal
Composition:
I
II
Cu
80%
85%
Sn
10%
15%
Pb
10%
-
 The term bronze covers a large number of copper alloys with varying percentages of Sn, Zn,
and Pb.bronze is one of the oldest known bearing materials.
Bronze:
o
Is easily worked.
o
Has good corrosion resistance andIs reasonably hard
o
Tin bronze (10 to 14% tin, remainder copper) is used in the machine and engine industry for
bearing bushes made from thin walled drawn tubes.
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ENGINEERING MATERIALS

Copper based alloy are employed for making bearing required to resist heavier pressures
such as in railways.

Tin base bearing material:
Composition:
Sn -88%
Sb - 8%
Cu - 4%
Tin based alloys preferred for higher load and speeds.
o
They posses low co-efficient of friction.
o
They also posses good ability to embed dirt
o
Good conformability to journal.
o
Good corrosion resistance
o
Very good seizure resistance etc.
Tin based alloys are used in high speed engines steam turbines.
8TH CHAPTER
SPRING MATERIALS
2 MARKS
Q.1.Give example of spring materials?
Ans:-Steel piano wire, Phosphor, Bronze, Nickels Silver, Montel, Inconel.
Q.2.List the types of spring material?
o
Ans; 1.Iron-based
o
2.Coper-based
o
3.Nickel-based
o
4.Special spring
Q.3.Write any two copper based spring materials with their composition?
Ans. Two copper based spring material are
o
Phosphor bronze; Cu=92%,
Sn=8%
o
Brass: Cu=67%
,Zn=33%
5 MARKS
Q.1. Name different types of iron based spring material and write their composition?
Ans: Different types of iron based spring materials are
Steel piano wire:C=0.7 to 1.0%,
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ENGINEERING MATERIALS
Mn=0.3 to 0.6% ,Fe=remainder
Hard-drawnspring wire:C=0.5 to 0.75%
Mn=0.6 to 1.2%
Fe=remainder
Oil hardened spring steel:C=0.55 to 0.75%
Mn=0.3 to0.9%
Fe=remainder
Cr-v spring steels:C=0.5%
Mn=0.8 to1.2%
Cr=0.2 to0.9%
v=0.07 to 0.12%
Fe=remainder
Stainless steel: Cr=18%
Ni=8%
C=0.1 to0.2%
Fe=remainder
Q.2.state the properties of cadmium based bearing material?
Ans: Properties:cadmium based bearing material possess
o
Low co-efficient of friction
o
High fatigue strength
o
High load carrying capacity
o
Low wear
o
Good seizure resistance
o
Fair ability to embed dirt
o
Poor corrosion resistance (using ordinary lubricant).
7 MARKS
Q.1.List properties of copper base spring material?
Ans: Copper based spring material:
They possess .high electrical conductivity.
Good resistance to corrosion and lack of magnetic properties.
Such material can be classed as

One which can be hardened only by cold deformation and

Other which can be hardened also by heat treatment.materials coming in the second
group can be formed in to spring while the material in the soft or half hard condition and
then required spring properties can be developed by heat treatment.

Various copper based spring material are:
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ENGINEERING MATERIALS
Phosphor bronze

Cu
Chemical composition
92%
Sn
8%
Uses:
High qualityspring for switches ,relays,contacts etc.
Brass

Chemical composition
Cu
67%
Zn
33%
Uses:
Switches and contact (spring)
Nickel silver

Chemical composition
Cu
56%
Ni
18%
Zn
25%
Uses:
Same as brass,but for better quality spring.
Beryllium copper
Chemical composition
Cu
98%
Be
2%
Uses:
Brushes,relays,switches,etc.with relatively good resistance to wear, good conductivity and
good resistance to corrosion.
CHAPTER-09
POLYMERS
2 MARKS
Q.1.What is elastomer ?
Ans:-An elastomer is a polymeric that may experience large and reversible elastic
deformations.Elastomers referred to as rubbers.They are essentially noncrystalline in structure.
Axial.
Q.2.Give example Of thermosetting and thermo plastic resins?
Ans:Example of thermosetting resin are-Alice’s,epoxies,melamine
Example of thermoplastic resins is ABS plastic, acetyls,acrylics.
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ENGINEERING MATERIALS
5 MARKS
Q.1. Explain the properties and application of thermoplastic?
Properties:-1.They can be repeatedly soften by heat and hardened by cooling.
2.They are comparatively soften and less strong
3.Objects made by thermoplastic resin cannot be used at comparatively higher temperature
as they will tend to soften under heat.
4.They are usually supplied as granular material.
Application:Toys,combs,toilet,goods, photographic films,insulating tapes,hoses,electric insulation
etc.
Q.2.what is the different between thermoplastic polymers and thermosetting polymers?
Ans:Thermoplastic Thermosetting
1.They can be repeatedly soften
1.Once hardened and set,they do not
By heat and hardened by cooling.
Soften application of heat.
2.they are softer and less strong.
2. They are more strongest and harden then
Thermoplastic polymer.
7 MARKS
Q.1.What is the difference between thermoplastics and thermosetting plastic?
Ans: Thermoplastic

They can be repeatedly softened by heat and hardened by cooling.

They are comparatively soften and less strong.

Object made by thermoplastic resin cannot be used at comparatively higher temperature as
they will tend to soften under heat.

They are usually supplied as granular material.
Application:
Toy, combs, toilet goods,photographic films,insulating tapes,hoses, electric insulation etc.
Thermosetting

The thermosetting resins one hardened and set ,they do not soften with the application of
heat.

They are stronger and harder.

Object s made by thermosetting resins can be used at comparatively higher temperature
without damage

The thermosetting reasons are usually supplied in monomeric or partially polymerized form in
which they are either liquids or partially thermoplastic solids.
Application: Thermosetting reasons are used in telephone receiver, electric plugs ,radio and TV
Cabinets,camera bodies. Automobiles parts , circuit s breaker switch panels.
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ENGINEERING MATERIALS
Q.2.Write the properties of elastomers?
Ans:An elastomer is a polymeric material which at room temperature can be stretched to at least twice
its original length and upon immediate release of the stress will return quickly to approximately to its
original length.
The main types of artificial rubber or elastomers which are given below.
1.properties of styrene rubber
o
It possesses high abrasive resistance ,high load bearing capacity and resilience.
o
It swells in oils and solvents.
2.Properties of nitrite rubber.
o
Extremely good oil resistance.
o
Low swelling
o
Excellent adhesion to metal .
Good tensile strength and abrasive resistance.
3.Butyl rubber

A low density rubber of low strength and high elongation

Outstanding permeability to gases

Excellent dielectric properties,

Excellent resistance to wear, abrasion,cutting and chipping damage.

Excellent resistance to weather, ozone ,sunlight,animal and vegetable oil.
4.Potychloroprone(Neoprene) rubber
o
Resistance to oil,paraffin’s,ozone and abrasion.
o
Swivels in oil and solvents.
o
Will not support combustion.
5.Fluorine rubber

Very good heat resistance

Good insulation properties.

Low strength

High in cost.
6.Polysulphide rubber

Excellent resistance to oil, solvents and water

Extremely low permeability to gases.

Good electrical resistivity.

Excellent adhesion to metal.
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ENGINEERING MATERIALS
CHAPTER-10
COMPOSITES AND CERAMICS
2 MARKS
Q.1.State the application of ceramic?
Ans:-Ceramic material can be as sand,glass, brick,cement.
Ceramic material are corrosion resistance and be used as concrete,insulator,abrasives,refractories
and plaster.
Q.2.Give four important characteristics of ceramics?
Ans:
 Brittleness
 Resistance to high temperature.
 Hardness
 It is insulator.
7 MARKS
Q.1. Explain fiber reinforced composites with their application?
Ans: Fiber reinforced composite:
Fiber reinforce component involves three components namely,filament,a polymer matrix and a
bonding agent.glass and metallic fibers commonly employed for this purpose.the fibers can be
employed either in the form of continuous,lengths,staples or whiskers.
Fire in composites provides stiffness and also density of the composite, where metal matrix is
used.Matrix provide toughness to the composite material, and it binds the fiber together.
The most familiar example of this category of composites is glass reinforced plastics, aluminum,boron
composite,. Boron has low density and is suitable for light weight application.
The fiber rein forced composites possess superior properties like higher yield strength,fracture
strength and fatigue life.to obtain composite having the maximum strength and elastic modulus. It is
essential that there should be maximum number of fiber per unit volume so that each fiber takes its
full share of load. The fiber reinforcedcomposites aregenerally anisotropic and the maximum strength
is in the direction of alignment of fibers.
For preparing a fiber reinforced composite it is essential that:
The co efficient of expansion of the fiber matches closely that of the matrix.
The fiber and matrix should be chemically compatible with each other and no undesirable reaction
takes place between them.
The fiber should be stable at room temperature and should retain a good percentage of strength at
elevated temperature.
Q.2.What is composites? Explain particle reinforced and fiber reinforced composites .state
their properties.
Ans: Thematerial which is produced by combing of two dissimilar materials into a new material that
may be better suited for a particular application then the original material is called composite.
The base material which is present in larger amount is called matrix. The other material is sometimes
known as reinforcing phase.
Classification of composite:
 Particle reinforced composites
 Fiber reinforced composites
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ENGINEERING MATERIALS
Particle reinforced composite: particle reinforced composite are made by dispersing particles of
varying size and shape of one material in the matrix of another material .the operation may be carried
out by adding particles to a liquidmatrix material,which later solidified (during age hardening) or may
be pressed together (by the powder process) in such composites, thematrix as well as particles share
the load bearing function. Example of such cermet (metal ceramic composites) used in cutting tools,
concrete used in dams, building etc. the effective strength of such composites depends to a great
extent on interparticles spinning.
As the volume fraction of the dispersion increases, the mechanical improve,reaching an optimum
value and then begin to fall. At higher volume fractions of the disperiods,the brittle ceramic particles
come closer to each other,thereby somewhat continuous brittle phase is formed which promotes
premature failure. For ex.in tungsten carbide-cobalt composite cermet’s, the maximum in tungsten
carbide- cobalt composite cermet’s., the maximum strength is attained around 66% volume
percentage. If tungsten carbide, after which it benefits to fall.
Fiber reinforced composite:fiber- reinforced components involves three components namely
,filaments, a polymer matrix and a bonding agent. Glass…. And metallic fibers commonly employed
for this purpose. The fiber can be employed either in the form of continuous,lengths,staples or
whiskers.
Fiber in composite provides stiffness and also density of composites, where metal matrix is used.
Matrix provides toughness to the composite material and it binds the fiber together.
The most similar example of this category of composites is glass-reinforced plastics,aluminum,boron
composite.boron has low density and is suitable for light weight applications.
The fiber reinforced composites possess superior properties like higher yield strength,fracture
strength and fatigue life. To obtain composite having the maximum strength and elastic modulus, it is
essential that there should be maximum number of fiber per unit volume so that each fiber takes its
full shares of load. The fiber reinforced composite are generally anisotropic and the maximum
strength is in the direction of alignment of fibers.
For preparing a fiber reinforced composite,it is essential that
The coefficient of expansion of the fiber matches closely that of the matrix.
The fiber and matrix should be chemically compatible with each other and no undesirable reaction
takes place between them.
The fiber should be stable at room temperature and should retain a good percentage of strength at
elevated temperatures.
Page 45