MANUAL

1. CE 8381 STRENGTH OF MATERIALS AND FLUID MECHANICS AND
MACHINERY LABORATORY
S.No. NAME OF EXPERIMENTS
1 ROCK WELL HARDNESS TEST
2 BRINELL HARDNESS TEST
3 IMPACT TEST- IZOD
4 IMPACT TEST- CHARPY
5 TORSION TEST ON MILD STEEL ROD
6 DEFLECTION TEST ON BEAM
7 DOUBLE SHEAR TEST ON GIVEN SPECIMEN
8 TENSILE TEST ON MILD STEEL
9
DETERMINATION OFMODULUS OF RIGIDITY- SPRING
TEST
10 STRAIN MEASUREMENT USING STRAIN GAUGE
11 HEAT TREATMENT PROCESS –HARDENING
12
TEMPERING IMPROVEMENT MECHANICAL PROPERTIES
COMPARISON
13
IDENTIFICATION OF HARDENED AND TEMPERED
MEDIUM CARBON STEEL

2. ROCK WELL HARDNESS TEST
AIM: -
To determine the hardness the Hardness of the given specimen using Rockwell hardness
test.
APPARATUS REQUIRED: -
1. Rockwell hardness testing machine
2. Black diamond cone indenter
3. Metal Specimen.
4. Emery paper
DIAGRAM:-
Rockwell hardness tester

3. THEORY: -
In Rock well hardness test consists in touching an indenter of standard cone or ball into
the surface of a test piece in two operations and measuring the permanent increase of depth of
indentation of this indenter under specified condition. From it Rockwell hardness is deduced.
The ball (B) is used for soft materials (e.g. mild steel, cast iron, Aluminum, brass. Etc.) And the
cone (C) for hard ones (High carbon steel. etc.)
HRB means Rockwell hardness measured on B scale
HRC means Rock well hardness measured on C scale
PROCEDURE: -
1. Clean the surface of the specimen with an emery sheet.
2. Place the specimen on the testing platform.
3. Raise the platform until the longer needle comes to rest
4. Release the load.
5. Apply the load and maintain until the longer needle comes to rest
6. After releasing the load, note down the dial reading.
7. The dial reading gives the Rockwell hardness number of the specimen.
8. Repeat the same procedure three times with specimen.
9. Find the average. This gives the Rockwell hardness number of the given specimen.
TABULATION:-
Specimen
Material
Name of the
Intender
(Inches)
Load
selected
(kg )
scale
Rock well Hardness Number
(RHN)
Trial-
1
Trial-
2
Average
(RHN)

4. PRECAUTIONS:-
1. Thickness of the specimen should not be less than 8 times the depth of indentation to
avoid the deformation to be extended to the opposite surface of a specimen.
2. Indentation should not be made nearer to the edge of a specimen to avoid unnecessary
concentration of stresses. In such case distance from the edge to the center of indentation should
be greater than 2.5 times diameter of indentation.
3. Rapid rate of applying load should be avoided. Load applied on the ball may rise a
little because of its sudden action. Also rapidly applied load will restrict plastic flow of a
material, which produces effect on size of indentation.
RESULT:-
Rockwell hardness number of mild steel = ………… RHN
Rockwell hardness number of copper = ………… RHN
Rockwell hardness number of aluminum = ………… RHN

5. BRINELL HARDNESS TEST
AIM:-
To find the Brinell Hardness number for the given metal specimen.
APPARATUS REQUIRED:-
1. Brinell Hardness Testing Machine
2. Metal Specimens
3. Brinell Microscope.
DIAGRAM:-
Brinell Hardness Tester

6. FORMULA:-
Brinell Hardness Number (BHN)=Load/Area Of Indenter
Brinell Hardness Number = 2P (BHN)
π D [D - √ ( D 2
– d 2
) ]
Where,
P = Load applied (Kg)
D = Diameter of the indenter (mm)
d = Diameter of the indentation (mm)
THEORY:-
It consists of pressing a hardened steel ball into a test specimen. In this usually
a steel ball of Diameter D under a load ‘P’ is forced in to the test piece and the mean
diameter ‘d’ of the indentation left in the surface after removal of load is measured. According
to ASTM specifications a 10 mm diameter ball is used for the purpose. Lower loads
are used for measuring hardness of soft materials and vice versa. The Brinell hardness
is obtained by dividing the test load ‘P’ by curved surface area of indentation.
This curved surface is assumed to be portion of the sphere of diameter ‘D’.
TEST REQUIREMENTS:-
1. Usual ball size is 10 mm + 0.0045 mm. Some times 5 mm steel ball is also used. It
shall be hardened and tempered with a hardness of at least 850 VPN. (Vickers Pyramid Number).
It shall be polished and free from surface defects.
2. Specimen should be smooth and free from oxide film. Thickness of the piece to be
tested shall not be less than 8 times from the depth of indentation.

7. 3. Diameter of the indentation will be measured n two directions normal to each other
with an accuracy of + 0.25% of diameter of ball under microscope provided with cross tables and
calibrated measuring screws.
PROCEDURE:-
1. Specimen is placed on the anvil. The hand wheel is rotated so that the specimen along
with the anvil moves up and contact with the ball.
2. The desired load is applied mechanically ( by gear driven screw) and the ball presses
into the specimen.
3. The diameter of the indentation made in the specimen by the pressed ball is measured
by the use of a micrometer microscope, having transparent engraved scale in the field of view.
4. The indentation diameter is measured at two places at right angles to each other, and
the average of two readings is taken.
5. The Brinell Hardness Number ( BHN) which is the pressure per unit surface area of the
indentation is noted down.
TABULATION:-
Specimen
Material
Load
(Kg )
Diamete
r
of the
Indenter
(mm)
Diameter of the indentation
in impression
(mm)
Brinell
Hardness
Number
(BHN)
Trial-1 Trial-2 Avg

8. PRECAUTIONS:-
1. Thickness of the specimen should not be less than 8 times the depth of indentation to
avoid the deformation to be extended to the opposite surface of a specimen.
2. Indentation should not be made nearer to the edge of a specimen to avoid unnecessary
concentration of stresses. In such case distance from the edge to the center of indentation should
be greater than 2.5 times diameter of indentation.
3. Rapid rate of applying load should be avoided. Load applied on the ball may rise a
little because of its sudden action. Also rapidly applied load will restrict plastic flow of a
material, which produces effect on size of indentation.
4. Surface of the specimen is well polished, free from oxide scale and any foreign
material.
RESULT:-
Brinell hardness number of mild steel = ………… BHN
Brinell hardness number of copper = ………… BHN
Brinell hardness number of aluminium = ………… BHN

9. IMPACT TEST- IZOD
AIM: -
To determine the impact strength of steel by Izod test
APPARATUS REQUIRED: -
1. Impact testing machine
2. A steel specimen 75 mm X 10mm X 10mm
DIAGRAM:-
Izod impact testing equipment Specimen for Izod test

10. FORMULA:-
I = K (J/mm2
)
A
Where,
I = Impact strength (J/mm2
)
K= Impact strength absorbed (J)
A= Area of cross section of specimen (mm2
)
THEORY:-
An impact test signifies toughness of material that is ability of material to absorb energy
during plastic deformation. Static tension tests of unnotched specimens do not always reveal the
susceptibility of a metal to brittle fracture. This important factor is determined by impact test.
Toughness takes into account both the strength and ductility of the material. Several engineering
materials have to withstand impact or suddenly applied loads while in service. Impact strengths
are generally lower as compared to strengths achieved under slowly applied loads. Of all types of
impact tests, the notch bar tests are most extensively used. Therefore, the impact test measures
the energy necessary to fracture a standard notch bar by applying an impulse load. The test
measures the notch toughness of material under shock loading. Values obtained from these tests
are not of much utility to design problems directly and are highly arbitrary. Still it is important to
note that it provides a good way of comparing toughness of various materials or toughness of the
same material under different condition. This test can also be used to assess the ductile brittle
transition temperature of the material occurring due to lowering of temperature.
PROCEDURE:-
1. With the striking hammer (pendulum) in safe test position, firmly hold the steel
specimen in impact testing machine’s vice in such a way that the notch face the hammer and is
half inside and half above the top surface of the vice.
2. Bring the striking hammer to its top most striking position unless it is already there,
and lock it at that position.

11. 3. Bring indicator of the machine to zero, or follow the instructions of the operating
manual supplied with the machine.
4. Release the hammer. It will fall due to gravity and break the specimen through its
momentum, the total energy is not absorbed by the specimen. Then it continues to swing. At its
topmost height after breaking the specimen, the indicator stops moving, while the pendulum falls
back. Note the indicator at that topmost final position.
5.Again bring back the hammer to its idle position and back.
OBESERVATION:-
Name of
specimen
Size of
specimen
Sizeof
fracture
(mm)
Area
of
notch
point
(mm2)
Frictional
energy
absorbed by
bearing
without
specimen(A)
(J)
Energy spent
in breaking
or bending
specimen(B)
(J)
Energy
absorbed
by the
specimen
(A-B)
(J)
Impact
strength
J/mm2
PRECAUTION:-
1. Measure the dimensions of the specimen carefully.
2. Hold the specimen (lzod test) firmly.
3. Note down readings carefully.
RESULT:-
The Charpy impact strength of given Mild Steel = …………(J/mm2
)

12. IMPACT TEST- CHARPY
AIM: -
To determine the impact strength of steel by Charpy test.
APPARATUS REQUIRED: -
1. Impact testing machine
2. A steel specimen 10mm X 10mm X 55 mm
DIAGRAM:-
Charpy impact testing equipment Specimen for Charpy test

13. FORMULA:-
I = K (J/mm2
)
A
Where,
I = Impact strength (J/mm2
)
K= Impact strength absorbed (J)
A= Area of cross section of specimen (mm2
)
THEORY:-
An impact test signifies toughness of material that is ability of material to absorb energy
during plastic deformation. Static tension tests of unmatched specimens do not always reveal the
susceptibility of a metal to brittle fracture. This important factor is determined by impact test.
Toughness takes into account both the strength and ductility of the material. Several engineering
materials have to withstand impact or suddenly applied loads while in service. Impact strengths
are generally lower as compared to strengths achieved under slowly applied loads. Of all types of
impact tests, the notch bar tests are most extensively used. Therefore, the impact test measures
the energy necessary to fracture a standard notch bar by applying an impulse load. The test
measures the notch toughness of material under shock loading. Values obtained from these tests
are not of much utility to design problems directly and are highly arbitrary. Still it is important to
note that it provides a good way of comparing toughness of various materials or toughness of the
same material under different condition. This test can also be used to assess the ductile brittle
transition temperature of the material occurring due to lowering of temperature.
PROCEDURE:-
1. With the striking hammer (pendulum) in safe test position, firmly hold the steel
specimen in impact testing machines vice in such a way that the notch faces is the hammer and is
half inside and half above the top surface of the vice.
2. Bring the striking hammer to its top most striking position unless it is already there,
and lock it at that position.

14. 3. Bring indicator of the machine to zero, or follow the instructions of the operating
manual supplied with the machine.
4. Release the hammer. It will fall due to gravity and break the specimen through its
momentum, the total energy is not absorbed by the specimen. Then it continues to swing. At its
topmost height after breaking the specimen, the indicator stops moving, while the pendulum falls
back. Note the indicator at that topmost final position.
5. The specimen is placed on supports or anvil so that the blow of hammer is opposite to
the notch.
OBESERVATION:-
Name of
specimen
Size of
specimen
Sizeof
fracture
(mm)
Area
of
notch
point
(mm2)
Frictional
energy
absorbed by
bearing
without
specimen(A)
(J)
Energy spent
in breaking
or bending
specimen(B)
(J)
Energy
absorbed
by the
specimen
(A-B)
(J)
Impact
strength
J/mm2
PRECAUTION:-
1.Measure the dimensions of the specimen carefully.
2 Locate the specimen (Charpy test) in such a way that the hammer, strikes it at the
middle.
3 Note down readings carefully.
RESULT:-
The Izod impact strength of given Mild Steel = ………… (J/mm2
)

15. TORSION TEST ON MILD STEEL ROD
AIM:-
To conduct torsion test on mild steel or cast iron specimens to find out modulus of
rigidity.
APPARATUS REQUIRED: -
1. A torsion testing machine.
2. Twist meter for measuring angles of twist
3. A steel rule and Vernier Caliper or micrometer.
DIAGRAM:-
Torsion testing machine

16. FORMULA:-
Where,
L = Length of the specimen (mm)
T = Torque applied (N-mm)
θ = Angle of twist (radians)
Ip = Polar moment of inertia (j)
= πd4
( mm4
)
32
I = πd4 ( mm4
)
64
PROCEDURE:-
1. Select the driving dogs to suit the size of the specimen and clamp it in the machine by
adjusting the length of the specimen by means of a sliding spindle.
2. Measure the diameter at about three places and take the average value.
3. Choose the appropriate range by capacity change lever
4. Set the maximum load pointer to zero.
5. Set the protector to zero for convenience and clamp it by means of knurled screw.
6. Carry out straining by rotating the handweel in either direction.
7. Load the machine in suitable increments.
8. Then load out to failure as to cause equal increments of strain reading.
9. Plot a torque- twist (T- θ) graph.
Modulus of rigidity (G) = TL (N/mm2
)
Ip θ

17. 10. Read off co-ordinates of a convenient point from the straight line portion of the
torque twist (T- θ) graph and calculate the value of C by using relation
OBESERVATION:-
Gauge length of the specimen L = ……… (mm)
Diameter of the specimen d = ……… (mm)
TABULATION:-
Torque
(×103
N)
Angle of twist (θ)
(degree)
Radian
(θ×π/180)
Mean
(N/mm2) Modulus of
Rigidity
(G)
(N/mm2
)
Experimental Theoritical
Mean=
PRECAUTION:-
1) Measure the dimensions of the specimen carefully
2) Measure the Angle of twist accurately for the corresponding value of Torque.
RESULT:-
The Modulus of rigidity of the specimen by analytical Method = ………. N/mm2
The Modulus of rigidity of the specimen by graphical Method = ……….. N/mm2

18. DEFLECTION TEST ON BEAM
AIM: -
To determine the Young’s modulus of the given specimen by conducting bending test.
APPARATUS REQUIRED: -
1. Deflection of beam apparatus
2. Dial gauge.
3. Weights
4. Beam of different cross-sections and material (say wooden and steel beams)
DIAGRAM:-
Specimen details and mounting

19. FORMULA:
(i) For central loading :
Where,
W =Load acting at the center ( N)
L =Length of the beam between the supports ( mm)
E =Young’s modulus of material of the beam ( N/mm2)
δ = Actual deflection (mm)
I = Moment of Inertia of the beam (mm4
)
= (bd3
/12)
b = Breadth of the beam (mm)
d = Depth of the beam (mm)
(ii) For non-central loading(x < a)
E = W b x (L2
-b2
-x2
) (N/mm2
)
68 IL
(iii) For non-central loading(x > a)
E = W b x (L2
-b2
-x2
) + W (x-a)3
(N/mm2
)
68 IL 68 IL
E = W L3
(N/mm2
)
48 δ I

20. THEORY:-
If a beam is simply supported at the ends and carries a concentrated load at its centre, the
beam bends concave upwards. The distance between the original position of the beams and its
position after bending at different points along the length of the beam, being maximum at the
centre in this case. This difference is known as ‘deflection’ In this particular type of loading the
maximum amount of deflection (δ) is given by the relation,
δ = W L3
48 EI ………… (i)
E = W L3
48 δ I ----------- (ii)
PROCEDURE:-
1. Adjust cast- iron block along the bed so that they are symmetrical with respect to the
length of the bed.
2. Place the beam on the knife edges on the block so as to project equally beyond each
knife edge. See that the load is applied at the centre of the beam
3. Note the initial reading of vernier scale.
4. Add a weight of 20N (say) and again note the reading of the vernier scale.
5. Go on taking readings adding 20N (say)each time till you have minimum six readings.
6. Find the deflection (δ) in each case by subtracting the initial reading of vernier scale.
7. Draw a graph between load (W) and deflection (δ) . On the graph choose any two
convenient points and between these points find the corresponding values of W and δ. Putting
these Values in the relation
δ = W L 3
48 EI
Calculate the value of E

21. OBSERVATION: -
1. Length of the specimen, L = mm
2. Breadth of the specimen, b = mm
3. Depth of the specimen, d = mm
4. Least count of the vernier caliper, LC = mm
TABULATION:-
(i) For central loading :
(ii) For non-central loading(x< a)

22. (iii) For non-central loading(x>a)
PRECAUTION:-
1. Make sure that beam and load are placed a proper position.
2. The cross- section of the beam should be large.
3. Note down the readings of the vernier scale carefully
RESULT:-
(i) BY ANALYTICAL METHOD:
The young’s modulus for central loading = ……………………N/mm2
The young’s modulus for non central loading (x<a) = ……………………N/mm2
The young’s modulus for non central loading (x>a) = ……………………N/mm2
(ii) BY GRAPHICAL METHOD:
The young’s modulus for central loading = ……………………N/mm2
The young’s modulus for non central loading (x<a) = ……………………N/mm2
The young’s modulus for non central loading (x>a) = ……………………N/mm2

23. DOUBLE SHEAR TEST ON GIVEN SPECIMEN
AIM: -
To conduct shear test on specimens under double shear.
APPARATUS REQUIRED: -
1. Universal testing machine.
2. Shear test attachment.
3. Test Specimens.
4. Vernier Caliper.
DIAGRAM:-
Shearing fixture

24. FORMULA:-
Shear strength = Maximum shear force (N/mm2
)
Area of the specimen.
Where,
Cross sectional area in double shear, (A) = 2 x π d
2
(mm
2
)
4
THEORY: -
Place the shear test attachment on the lower table, this attachment consists of cutter. The
specimen is inserted in shear test attachment & lift the lower table so that the zero is adjusted,
then apply the load such that the specimen breaks in two or three pieces. If the specimen breaks
in two pieces then it will be in single shear & if it breaks in three pieces then it will be in double
shear.
PROCEDURE:-
1. Insert the specimen in position and grip one end of the attachment in the upper portion
and one end in the lower portion.
2. Switch on the main switch of universal testing machine.
3. The drag indicator in contact with the main indicator.
4. Select the suitable range of loads and space the corresponding weight in the pendulum
and balance it if necessary with the help of small balancing weights.
5. Operate (push) buttons for driving the motor to drive the pump.
6. Gradually move the head control level in left-hand direction till the specimen shears.
7. Down the load at which the specimen shears.
8. Stop the machine and remove the specimen
9. Repeat the experiment with other specimens.

25. OBESERVATION:-
Diameter of the Rod, d = ……… (mm)
Cross sectional area in double shear , A = 2 x π d
2
(mm2)
4
Shear load taken by the Specimen at the time of failure , W = ……… ( N)
Shear strength = Maximum shear force
Area of the specimen
τ = 4W (N/mm2
)
2 x π d
2
PRECAUTION:-
1. The measuring range should not be changed at any stage during the test.
2. The inner diameter of the hole in the shear stress attachment should be slightly greater
than that of the specimen.
3. Measure the diameter of the specimen accurately.
RESULT:-
Shear strength of the specimen ………N/mm 2

26. TENSILE TEST ON MILD STEEL
AIM: -
To conduct a tensile test on a mild steel specimen and determine the following:
(i) Yield stress (ii) Ultimate stress
(iii) Actual breaking stress (iv) Percentage of Elongation
(v) Percentage reduction in area. (vi) Young’s modulus of elasticity
(vii) Linear Strain (viii) Lateral Strain
APPARATUS REQUIRED: -
1. Universal Testing Machine (UTM)
2. Mild steel specimens
3. Graph paper
4. Scale
5. Vernier Caliper
DIAGRAM:-
Universal testing machine Mild steel specimens

27. FORMULA:-
(1) Original area of the rod = π x (Original diameter of cross section ) 2
(mm2
)
4
(2) Final area of the rod = π x ( Neck diameter) 2
(mm2
)
4
(3)Yield stress = Yield load (N/mm2
)
Original area of cross-section
(4) Ultimate stress = Ultimate load (N/mm2
)
Original area of cross-section
(5) Actual breaking stress = Breaking load (N/mm2
)
Neck area
(6) Young’s modulus, E = Normal breaking stress (N/mm2
)
Linear strain
(7) Percentage of elongation = Neck length – Original gauge length x100 (%)
Original gauge length
(8) Percentage reduction in area = Original area – Neck area x100 (%)
Original area
(9) Linear Strain = Change in length (No unit)
Original length
(10) Lateral Strain = Change in diameter (No unit)
Original diameter

28. THEORY:-
The tensile test is most applied one, of all mechanical tests. In this test ends of
test piece are fixed into grips connected to a straining device and to a load measuring
device. If the applied load is small enough, the deformation of any solid body is
entirely elastic. An elastically deformed solid will return to its original from as soon as load is
removed. However, if the load is too large, the material can be deformed permanently. The initial
part of the tension curve which is recoverable immediately after unloading is termed. As elastic
and the rest of the curve which represents the manner in which solid undergoes plastic
deformation is termed plastic. The stress below which the deformations essentially
entirely elastic is known as the yield strength of material. In some material the onset of plastic
deformation is denoted by a sudden drop in load indicating both an upper and a lower yield
point. However, some materials do not exhibit a sharp yield point. During plastic deformation, at
larger extensions strain hardening cannot compensate for the decrease in section and thus the
load passes through a maximum and then begins to decrease. This stage the “ultimate strength”’
which is defined as the ratio of the load on the specimen to original cross-sectional area, reaches
a maximum value. Further loading will eventually cause ‘neck’ formation and rupture.
F Stress-strain diagram

29. PROCEDURE:-
1) Measure the original length and diameter of the specimen. The length may either be
length of gauge section which is marked on the specimen with a preset punch or the total length
of the specimen.
2. Insert the specimen into grips of test machine and attach strain-measuring device to it.
3. Begin the load application and record load versus elongation data.
4. Take readings more frequently as yield point is approached.
5. Measure elongation values with the help of dividers and a ruler.
6. Continue the test till Fracture occurs.
7. By joining the two broken halves of the specimen together, measure the final length
and diameter of specimen.
OBESERVATION: -
Overall Length of the Rod = ----------- (mm)
Gauge Length of the Rod = ----------- (mm)
Yield Load = ----------- (N)
Ultimate Load = ----------- (N)
Breaking load = ----------- (N)
Original dimensions of the Rod:
Length = ----------- (mm)
Diameter = ----------- (mm)
Area = ----------- (mm2
)
Final Dimensions of the Rod:
Neck Length = ----------- (mm)
Neck Diameter = ----------- (mm)
Neck Area = ----------- (mm2
)

30. GRAPH :-
Draw a graph between Elongations (X-axis) and load (Y-axis).
PRECAUTION:-
1. If the strain measuring device is an extensometer it should be removed before necking
begins.
2. Measure deflection on scale accurately & carefully
RESULT:
1. Yield stress = ______ N/mm2
2. Ultimate stress = ______ N/mm2
3. Actual Breaking stress = ______ N/mm2
4. Percentage of Elongation = ______ %
5. Percentage reduction in area = ______ %
6. Normal Breaking Stress = ______ N/mm2
7. Linear Strain = ______ No unit
8. Lateral Strain = ______ No unit
9. Young’s modulus = ______ N/mm2

31. DETERMINATION OFMODULUS OF RIGIDITY- SPRING TEST
AIM:-
To determine the modulus of rigidity and stiffness of the open coil spring.
APPARATUS REQUIRED:-
1. Spring test machine
2. Tension spring specimen
3. Vernier caliper
FORMULA:-
1. Modulus of rigidity (N) = 64 WR3
n cos  N/mm2

    D4
X δ
Where,
W = Load in N
D = Outer diameter of the spring in mm.
d = Diameter of the spring coil in mm
R = Mean Radius of the spring = (D – d /2) in mm
= Helix angle of spring
δ = Deflection of the spring in mm
2. Pitch = L / n-1 (mm)
Where,
L = Length of spring in mm
N = no of turns in spring
3. Tan = pitch / 2πR
4. Shear Stress(τ) = 16 W R cos  N/mm2

   π d3
5.Stiffness of spring (K) = W / δ N/mm
6. Flexibility factor (a) = 1/K mm/N

32. THEORY: -
Springs are elastic member which distort under load and regain their original shape when
load is removed. They are used in railway carriages, motor cars, scooters, motorcycles,
rickshaws, governors etc. According to their uses the springs perform the following Functions:
1) To absorb shock or impact loading as in carriage springs.
2) To store energy as in clock springs.
3) To apply forces to and to control motions as in brakes and clutches.
4) To measure forces as in spring balances.
5) To change the variations characteristic of a member as in flexible
mounting of motors.
The spring is usually made of either high carbon steel (0.7 to 1.0%) or medium carbon
alloy steels. Phosphor bronze, brass, 18/8 stainless steel and Monel and other metal alloys are
used for corrosion resistance spring. Several types of spring are available for different
application. Springs may classified as helical springs, leaf springs and flat spring depending upon
their shape. They are fabricated of high shear strength materials such as high carbon alloy steels
spring form elements of not only mechanical system but also structural system. In several cases it
is essential to idealise complex structural systems by suitable spring.
PROCEDURE:
1. By using vernier caliper measure the diameter of the wire of the spring and also the
diameter of spring coil.
2. Count the number of turns.
3. Insert the spring in the spring testing machine and load the spring by a suitable weight
and note the corresponding axial deflection in compression.
4. Increase the load and take the corresponding axial deflection readings.
5. Plot a curve between load and deflection. The shape for the curve gives the stiffness of
the spring

33. OBSERVATION:-
No of turns in spring (n) =
Diameter of the Spring coil (d) =
Length of the spring =
Outer diameter of the spring (D ) =
TABULATION:-
Load
(N)
Deformation
(δ)
(mm)
Mean
deformation(δ)
(mm)
Rigidity
Modulus
(N/mm2)
Shear
Stress(τ)
(N/mm2)
Stiffness
factor (K)
(N/mm2)
Flexibility
factor (a)
(mm/N)
Loading Unloading
GRAPH:-
Plot a curve between load (X-axis) and deflection (Y-axis)
PRECAUTION:-
1)The dimension of spring was measured accurately.
2) Deflection obtained in spring was measured accurately
RESULT:
The modulus of rigidity of the given spring by analytical method = ----------- N/mm2
The modulus of rigidity of the given spring by graphical method = ------------ N/mm2
The stiffness of the given spring = ----------- N/mm2

34. STRAIN MEASUREMENT USING STRAIN GAUGE
AIM:-
To measure the strain using strain gauge.
APPARATUS REQUIRED:-
1. Galvanometer
2. Weight Slots
3. Cantilever Beam
FORMULA:-
Strain = PL x 4 (No unit)
{2bt2E} 2
12 12
Where,
P = load (kg)
L = Length (mm)
B = Breadth (mm)
E = Young’s Modulus (kg/mm2
)
THEORY:-
CANTILEVER BEAM SET UP:-
A single cantilever beam with strain gauge on the top surface serves as an elastic member
the gauge are mount in stone bridge circuit the load applied at the end of a beam causes a change
in elastic strain energy gauge mount at the other end of the cantilever beam.

35. PROCEDURE:-
1. Connect the cantilever beam to the strain indicator using a chord cable.
2. Plug the main chord to 230/50 Hz AC main.
3. Switch on instrument.
4. Then the potentiometer switch to read position adjusts zero potentiometer until switch
to read position.
5. Turn the switch to call position adjust the potentiometer until the display reads.
6. Turn the function switch to read position.
7. Apply the load is turn of 100gm.
8. Display directly shows the microstructure for corresponding.
9. A graph is drawn between calculated value Vs indicated value reading.
OBSERVATION:-
Length (L) = ……. (mm)
Breadth(b) = ……. (mm)
Thickness(t) = ……. (mm)
Young’s modulus of Aluminium = 0.7 x 104
(kg/mm2
)
TABULATION :-
S.no Applied load
(kg)
Indicated reading
X 104 (no unit)
Calculated reading
X 104 (no unit)
RESULT:-
Here, by using the strain gauge we measure the strain and calculated reading are verified.

36. HEAT TREATMENT PROCESS –HARDENING
AIM:-
To increase the hardness of the metal by quenching the steel in the heat treatment process.
APPARATUS REQUIRED:-
1. Furnace
2. Rockwell hardness machine
3. Mild steel
4. Quenching media –sand, oil, water.
FORMULA:-
Impact strength = Energy absorbed (J/mm2
)
Size of the fracture
DEFINITION:-
Hardening is the treatment of steel which increases the hardness by quenching tool and
machine parts required to undergo heavy-duty service and oftenly hardness. The hardness of
steel requires the formation of martensite.
PURPOSE:-
 Hardness steel to resist wear.
 Enable steel to cut other material.
 It improves strength, toughness and ductility.
 Develops test combination of strength and notch ductility.
PROCEDURE:-
 Hardness of the given material is found out using Rockwell hardness testing machine.
 Here the given material is mild steel and it is heated to proper hardening temperature in
the austenite zone.
 The steel object is to be cooled rapidly in quenching media such as water, oil, sand till the
object reaches low temperature.
 After attaining room temperature again using Rockwell hardness testing machine the
hardness of the mild steel is found out .comparing the low hardness values we can study
the decrease in hardness of mild steel due to normalizing.

37. TABULATION:-
Name of the material
Unhardened specimen Tempered(Hardened)
specimen
Hardness
(J)
Impact
strength
(J/mm2
)
Hardness
(J)
Impact strength
(J/mm2
)
RESULT:-
Impact mild steel of mild steel before annealing = ………. (J/mm2
)
Impact mild steel of mild steel after annealing = ………. (J/mm2
)
So, the desirable conditions and properties are achieved by the steel due to
hardening process.

38. TEMPERING IMPROVEMENT MECHANICAL PROPERTIES
COMPARISON
AIM:-
To compare the mechanical properties of unhardened specimen quenched specimen and
quenching tempered specimen.
APPARATUS REQUIRED:-
1. Furnace
2. Rockwell hardness machine
3. Mild steel
4. Tongs
THEORY:-
Quench hardening or tempering produces structure of martensite and retained
austenite.The retained austenite is to an unstable phase and as it changed with time. Therefore
necessary to return towards equilibrium after quench hardening by heating the steel to a
temperature below the lower critical temperature (A1)705°C this is called tempering
PURPOSE OF HARDENING:-
 Relieve residual stress
 Improve ductility
 Improve toughness
 Increase % of elongation
PROCEDURE:-
 The unhardened work specimen is loaded in the furnace heating to critical temperature
above 700°C
 Then the work piece is quenched in the water medium.
 The impact strength and hardness of hardened material is found by Rockwell hardness
and impact testing machine.
 After hardening process the work piece is loaded and heated to lower critical temperature
and keep it in the furnace .
 Then the specimen having impact strength and hardness can be found by using Rockwell
and impact test (Izod test).
 The tempered materials having improved in mechanical properties then the hardened
specimen002E

39. TABULATION:-
Name of the material
Unhardened specimen Tempered specimen
Hardness
(J)
Impact
strength
(J/mm2
)
Hardness
(J)
Impact strength
(J/mm2
)
Quenched specimen
Hardness
(J)
Impact strength
(J/mm2
)
RESULT:-
(i) Unhardened specimen :
Hardness =………….. (J)
Impact strength =………….. (J/mm2
)
(ii) Tempered specimen :
Hardness =………….. (J)
Impact strength =………….. (J/mm2
)
(iii) Quenched specimen :
Hardness =………….. (J)
So the desired condition and properties of metal or alloy by tempering
process have been obtained.

40. IDENTIFICATION OF HARDENED AND TEMPERED MEDIUM
CARBON STEEL
AIM:-
To identify the given specimen using metallurgical microscope.
APPARATUS REQUIRED:-
1. Metallurgical microscope
2. Aluminium powder
3. Disc polishing machine
4. Etchent
5. Emery paper.
SPECIFICATION:-
 Magnification-100
 Etchent-2%
 Mechanical treatment- NIL
 Time of etching-5sec
PROCEDURE:-
 The specimen was first grained using emery paper on the same direction
 Then the specimen was grained in the rotating wheel covered with velvet cloth adding
water.
 The specimen was washed with water without touching it with hand and resorted by
layer.
 After, the specimen was washed and then the microscope with the application of
etching over its surface.
 The microstructure of the specimen was obtained by the adjustment.

41. MICROSTRUCTURE:-
The microstructure reveals tempered martensite structure the specimen is medium carbon
steel austenised at 840°
C half an hour and quenched in oil , the hardened specimen is tempered
at a temperature of 200°
C for one hour medium carbon steel contain carbon from 0.3 to 0.7%
PROPERTIES:-
 Steel having 0.35-0.45% carbon have a tensile strength of 79N/mm2
. Steel is containing
0.45-0.55%.
 Good strength
 Good wear resistance
 Uniform grain size.
USES:
 Automobile industry
 Railway industry
RESULT:
Thus the given specimen is identified as hardened and tempered medium carbon steel.