Kanpur Institute of Technology

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Nov 15, 2013 (3 years and 11 months ago)

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Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No : ………….


Object :

To obtain the Brinnel Hardness Number for the given work piece with the help of Rockwell and Brinnel
Hardness Testing Machine.


Apparatus / Equipment :



Rockwell and Brinnel Hardness Testing Machine



Steel Ball Indenter



Speci
men



Brinnel Microscope (optical)


Formula Used / Theory :








Where,

BHN

: Brinnel Hardness Number









P

: Major Load in kgf









D

: Diameter of Steel Ball Indenter in mm









d

: Diameter of indentation in mm


Procedure :



Clean the test

specimen and place it on the worktable of the machine



Turn the capstan wheel to elevate the test piece table and make it in contact with indenter.



Further turn the wheel by about 2.5 turn, forcing against the indenter. Now, it should be ensured that
minor

load of 10 kgf has been applied.



Set the pointer on the dial scale at the appropriate position, depending on the scale being used.



Push back gradually the load application lever of the machine, to apply the major load.



As soon as pointer comes in rest, pu
sh or pull the handle in the reverse direction to unload the major
load. The pointer will now rotate in reverse direction.



Measure the diameter of indentation of the specimen under the optical microscope.

2 P



D [ D


(D
2



d
2
)
1/2

]

BHN =

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Observations :

Take at least six observations for
the same

Major
Load

Dia of Indenter
(steel ball) in mm

Diameter of Indentation (in mm)

Set
-

1

Set
-

2

Set
-

3

Set
-

4

Set
-

5

Set


6










Calculation :



Calculate the Brinnel Hardness number for each observation by using :








Where,

BHN

:

Brinnel Hardness Number









P

: Major Load in kgf









D

: Diameter of Steel Ball Indenter in mm









d

: Diameter of indentation in mm



Take mean of all results.


Result :

The Brinnel Hardness number of given specimen is ……


Precautions :



Do no
t rotate capstan wheel by more than 2.5 turns approximately.



Surface of the specimen must be clean.



Major load should be applied gradually.



Indentation should not be made on the edge of the specimen



The specimen should be free from internal defects.


Quest
ions :



Define strength, Hradness and Toughness.



Define Rockwell Hardness Number.



Define Brinnel Hardness Number.



Describe various scales and indenters used in Hardness Testing.


2 P



D [ D


(D
2



d
2
)
1/2

]

BHN =

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No : …..

Object :

To conduct the Annealing Heat Treatment process
es and compare the hardness of the specimen before and
after the heat treatment process.


Apparatus / Equipment and Specifications :



Muffle Furnace (Electrically Operated)



Specimen of Mild Steel / Cast Iron



Brinnel Hardness Testing Machine



Optical Micros
cope



Specimen


Theory and Formula Used :

Heat treatment is the process of heating, soaking and cooling of material so as to alter the mechanical
properties. Initially, the specimen is heated to pre
-
required temperature and held at some time. This holding

time is known as soaking period. After that, material is allowed to cool in various mediums. Depending
upon the cooling rate, there are following types of Heat Treatment processes :

1. Annealing


2. Normalizing


3. Hardening

In annealing, material is allo
wed to cool in the furnace itself and the cooling rate is least. The hardness of
specimen is tested initially and then heat treatment is carried out. After the cooling of specimen, again the
hardness is calculated. Rockwell and Brinnel Hardness Testing Mac
hine (Brinnel Hardness Number or
Rockwell Hardness Number) is used to get the hardness values before and after the heat treatment process.

Where,

BHN

: Brinnel Hardness Number









P

: Major Load in kgf









D

: Diameter of Steel Ball Indenter in
mm









d

: Diameter of indentation in mm

Procedure :



Calculate the hardness value of the given specimen.



Put the specimen in the muffle furnace and heat it above the critical temperature (above thee re
-
crystallization temperature).



Allow some time to

soak the heat.



Cool the specimen. For annealing, put the specimen in the furnace itself and switch
-
off the furnace
and allow the cooling of specimen in the furnace itself.



After cooling, note the respective hardness value.


2 P



D [ D


(D
2



d
2
)
1/2

]

BHN =

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Observations :

Heating Tempera
ture for Mild Steel

: 950
0
C

Quenching Medium



: Water at room temperature

Heat Treatment (H/T) Process

: ……………………….

S.
No.

For Rockwell Hardness Testing

For Brinnel Hardness Testing

Hardness
Before H/T

Hardness
After H/T

Change

Status

Hardness
Before

H/T

Hardness
After H/T

Change

Status

1









2









3









4










Result :

For the given specimen, the harness value (Rockwell Hardness No / Brinnel Hardness No.) increases or
decreases by ……… during the Annealing Heat Treatment Process.


Precautions :



For hardness checking, surface of specimen must be clean and proper indenter and load should be
chosen carefully.



Heating should be dome above the re
-
crystallization temperature.



Soaking time should be given.



Cooling should be at prescribed

rate.



All the reading should be taken carefully.


Questions :



Define Annealing / Normalizing and Hardening Process.



Explain the advantage and disadvantages of Annealing.



Name the mechanical properties that are changed by this heat treatment process.




Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No : …..

Object :

To conduct the Normalizing Heat Treatment processes and compare the hardness of the specimen before
and after the heat treatment process.


Apparatus / Equipment and Specifications :



Muffle Furnace (Electrically Operated)



Spe
cimen of Mild Steel / Cast Iron



Brinnel Hardness Testing Machine



Optical Microscope



Specimen


Theory and Formula Used :

Heat treatment is the process of heating, soaking and cooling of material so as to alter the mechanical
properties. Initially, the spec
imen is heated to pre
-
required temperature and held at some time. This holding
time is known as soaking period. After that, material is allowed to cool in various mediums. Depending
upon the cooling rate, there are following types of Heat Treatment proces
ses :

1. Annealing


2. Normalizing


3. Hardening

In case or normalizing, material is allowed to cool in the air and has more cooling rate wrt annealing. The
hardness of specimen is tested initially and then heat treatment is carried out. After the cooling
of specimen,
again the hardness is calculated. Rockwell and Brinnel Hardness Testing Machine (Brinnel Hardness
Number or Rockwell Hardness Number) is used to get the hardness values before and after the heat
treatment process.

Where,

BHN

: Brinnel Hardn
ess Number









P

: Major Load in kgf









D

: Diameter of Steel Ball Indenter in mm









d

: Diameter of indentation in mm

Procedure :



Calculate the hardness value of the given specimen.



Put the specimen in the muffle furnace and heat it above
the critical temperature (above thee re
-
crystallization temperature).



Allow some time to soak the heat.



Cool the specimen. For normalizing, put the specimen in the air and allow it to cool.



After cooling, note the respective hardness value.


2 P



D [ D


(D
2



d
2
)
1/2

]

BHN =

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Observations :

Heating Temperature for Mild Steel

: 950
0
C

Quenching Medium



: Water at room temperature

Heat Treatment (H/T) Process

: ……………………….

S.
No.

For Rockwell Hardness Testing

For Brinnel Hardness Testing

Hardness
Before H/T

Hardness
After H/T

Change

Status

Hardness
Before H/T

Hardness
After H/T

Change

Status

1









2









3









4










Result :

For the given specimen, the harness value (Rockwell Hardness No / Brinnel Hardness No.) increases or
decreases by ……… during the Normalizing Heat
Treatment Process.


Precautions :



For hardness checking, surface of specimen must be clean and proper indenter and load should be
chosen carefully.



Heating should be dome above the re
-
crystallization temperature.



Soaking time should be given.



Cooling shoul
d be at prescribed rate.



All the reading should be taken carefully.


Questions :



Define Annealing / Normalizing and Hardening Process.



Explain the advantage and disadvantages of Normalizing.



Name the mechanical properties that are changed by these heat tre
atment processes.



Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No : …..

Object :

To conduct the Hardening Heat Treatment processes and compare the hardness of the specimen before and
after the heat treatment process.


Apparatus / Equipment and Specifications :



Muffle Furnace (Electric
ally Operated)



Specimen of Mild Steel / Cast Iron



Brinnel Hardness Testing Machine



Optical Microscope



Specimen


Theory and Formula Used :

Heat treatment is the process of heating, soaking and cooling of material so as to alter the mechanical
properties.
Initially, the specimen is heated to pre
-
required temperature and held at some time. This holding
time is known as soaking period. After that, material is allowed to cool in various mediums. Depending
upon the cooling rate, there are following types of Hea
t Treatment processes :

1. Annealing


2. Normalizing


3. Hardening

In case of Hardening, the material is allowed to cool suddenly and the cooling rate is maximum. For this
purpose, material is dipped either into water or in oil and cool it suddenly. Such s
udden cooling process is
termed as quenching. The hardness of specimen is tested initially and then heat treatment is carried out.
After the cooling of specimen, again the hardness is calculated. Rockwell and Brinnel Hardness Testing
Machine (Brinnel Hardn
ess Number or Rockwell Hardness Number) is used to get the hardness values
before and after the heat treatment process.

Where,

BHN

: Brinnel Hardness Number









P

: Major Load in kgf









D

: Diameter of Steel Ball Indenter in mm









d

: Dia
meter of indentation in mm

Procedure :



Calculate the hardness value of the given specimen.



Put the specimen in the muffle furnace and heat it above the critical temperature (above thee re
-
crystallization temperature).



Allow some time to soak the heat.



Coo
l the specimen. For hardening, dip the specimen in the water (quench it) to cool it suddenly.



After cooling, note the respective hardness value.

2 P



D [ D


(D
2



d
2
)
1/2

]

BHN =

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Observations :

Heating Temperature for Mild Steel

: 950
0
C

Quenching Medium



: Water at room temperature

Hea
t Treatment (H/T) Process

: ……………………….

S.
No.

For Rockwell Hardness Testing

For Brinnel Hardness Testing

Hardness
Before H/T

Hardness
After H/T

Change

Status

Hardness
Before H/T

Hardness
After H/T

Change

Status

1









2









3









4










Result :

For the given specimen, the harness value (Rockwell Hardness No / Brinnel Hardness No.) increases or
decreases by ……… during the Hardening Heat Treatment Process.


Precautions :



For hardness checking, surface of specimen must be clean and pro
per indenter and load should be
chosen carefully.



Heating should be dome above the re
-
crystallization temperature.



Soaking time should be given.



Cooling should be at prescribed rate.



All the reading should be taken carefully.


Questions :



Define Annealing
/ Normalizing and Hardening Process.



Explain the advantage and disadvantages of Hardening.



Name the mechanical properties that are changed by these heat treatment processes.



Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No #

Object


To obtain the spring index for the given spring in co
mpression and tension with the help of Spring Testing
Machine.


Apparatus used


Spring
-
testing machine, closely coiled helical spring, Dead weights etc.


Specification / Theory / formula used


Spring index (spring rate or spring stiffness) is defined as

the load P that causes unit deflection


in the
spring. This deflection is in the form of contraction in a compression spring in the form of extension in a
tension spring. Thus



Spring index is

an important parameter in selection of spring for a particular use. It is expressed in kN/cm or
kg/mm etc.the nature of load vs deflection curve decides whether the behavior of spring is linear or non
linear. Mostly close coil helical spring have linear n
ature.

Deflection of a close coiled helical spring can be evaluated analytically by a derived formula given below






= [ 8 P D
3

n ] / G d
4


Where p is the axial load (tensile

or compressive) D is mean of coil diameter of the spring, n is number of
coils is modulus of rigidity of spring material, and d is the spring wire diameter. In an experiment if

is
obtained different loading, shear modulus G can be dtermined experimentall
y by the above formula.


The maximum shear stress


induced in the spring can be determined by


= 8 P D
2

/ (


d
4
)


Procedure



1
-
set the load pointer at zero on machine head .Set the at zero division for deflection measurement. Remove
or note any zero

on these scales.

2
-
Determine diameter of the spring wire by micrometer at any two locations, which are perpendicular to
each other.

3
-
measure outside or inside diameter of the coil, and determine mean of the coil diameter by subtracting or
adding the dia
meter respectively.

4
-
Fasten the support attachment on machine and attach the spring on it. Use support table for compression
test and hook for tensile test.

5
-
now apply the load by rotating the handle. Read the applied load on load indicator and correspo
nding
deflection of the spring on venier scale.

6
-
For loads more than the machine head reading, put dead weights on left side pan. Repeat it by increasing
the load in step such as 1Kg, 1.5Kg, 2Kg ……5Kg.record the spring deflection for each time.

Spring Index =

P /


Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Observati
on table
-


Tension spring (During loading)

S. No.

Load (Kg)

Deflection (mm)














Compression table (during loading)

S. No.

Load (Kg)

Deflection (mm)














Calculation



Result



Precautions

1.do not operate a machine unless you
know its operations.

2.avoid a very fast rate of loading on machine.


Ques. for discussion
-

1
-

How you will define a spring?

2
-

How do we take into account the effect of weight the spring?

3
-

How we can test a leaf spring for its stiffness?

4
-

What do you mean by clos
e
-
coiled helical spring? How it is different form openly coiled helical
spring?

5
-

During test, deformation caused in a springs of elastic nature or plastic nature?


========================
Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment no.

Object
-


Compare the actual deflection measured with
dial gauge to the theoretical one, evaluated by young’s
modulus of beam for the given beam.


Apparatus used
-

Steel beam, Bending test apparatus, dial gauge or spherometer, scale, dead weights etc.


Specification / Theory /formula used
-

For a simply support
ed beam of span l, subjected to a point (connected)load w at its mid span, the deflection
y at the center of span can be calculated by the fallowing formula

y = ( W l
3

) / (48 EI)

Where E is young’s modulus of material of the beam, I is its area moment of

inertia about natural axis.


Procedure
-


1
-
First of all the beam is kept horizontal and supported on two supports. Distance between the supports i.e.
the span l is noted.

2
-
width b and depth d of the beam cross section is measured to calculate its moment
of inertia.

3
-
the dead w is placed on the mid span and deflection so caused. Is recorded by a dial


Gauge or a spherometer

4
-
The weight w is increased in steps of 0.5Kg and deflection each time for corresponding loads.

5
-
the observation may also taken b
y varying the span.


Observation table
-

During loading

-

S. No

Load (Kg)

Deflection recorded (mm)




















Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

During unloading
-

S. No.

Load (Kg)

Deflection recorded (mm)




















Calculation
-


Result
-



Precautions
-


1
-
Avoi
d touching the etched surface specimen or placing it on rough ground.

2
-
Avoid very fast rate of loading on machine.



Questions For discussion
-


1
-
how will you define a beam?

2
-
What do you mean by pure bending of beam?

3
-
Quoute some example of beam that e
xist as machine components?

4
-
How can we get almost exact simple support condition in beam bending test?

===============================
Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No : …………..

Object :

Comparative Study of micro
-
structures for various given specimen.


Equipment :

Properly

Polished and Prepared Specimen, Metallurgical Microscope etc.


Theory :

There are two type of material structures as : Macro Structure and Micro Structures. Macrostructure can be
visualized by un
-
aided human eyes while microstructures are not visible by u
n
-
aided human eye. High
magnification metallurgical microscopes are required to observe the microstructures of given specimen.

In steels and gray Cast iron, various micro
-
constituents are visualized. The various micr0
-
phases are ferrite
and cementite. Alt
ernate layer of ferrite and cementite is known as pearlite.

Metallurgical microscope is such microscope in which illumination is horizontal. The image is formed by the
reflected light by the specimen surface. Eyepiece is used to magnify the image. Total ma
gnification powwer4
of microscope is as :

M = D M
1

M
2

/ 250


where, M
1

= Initial Magnification of the objective








M
2

= Magnification of Eyepiece








D = Projection Distance

For entire practical purpose, we use M = M
1

x M
2

where M
1

= 10X and M
2

=

5 X or 20 X


Procedure :



Prepare the specimen by Cutting, Polishing and Etching.



On the power suppy, put the specimen on the table of microscope.



Focus the microscope, and visualize the microstructure.



Repeat the process for various given specimen.


Obser
vation :

The microstructure for various given specimen is visualized.

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Result :


The microstructure for various given specimen is visualized.


Precautions :



Carefully use the microscope.



Do not touch the polished surface of specimen.



Do not touch the eyepi
ece lens.


Questions for Discussion :



Define various levels of microstructures.



Define various micro
-
constituents of Iron
-
Carbide Phase Diagram.


==========================



Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

Experiment No. : ………..

Object :

To conduct the Fatigue test on given specimen.


Equipment :

Specimen, Fatigue Testing Machine, Dead Weights etc.


Theory :

The behaviour of material under the fluctuating and reversing loading is known as Fatigue. Due to cyclic
loading and unloading, the material get failed prior to its ultimate strengt
h. Such limit is termed as Fatigue
Strength and failure due to such loading conditions (owing to fatigue) is termed as Fatigue Failure. It is also
termed as Endurance Limit and is about 0.3 to 0.5 times the ultimate strength of the material. Total number
o
f cycles (N) required to bring the material about fracture under applied stress defines the Fatigue Life.


The endurance stress can be calculated as :

Goodman’s Straight Line Relation:





a

=

e



Soderberg’s Straight Line Relation :





a

=

e





Where,


a
=
Alternation Stress



e
=
Endurance Stress


u
=
Ultimate Stress ( = 650 M Pa
-

say)



y
=
Yield Stress

( = 520 M Pa


say)

FOS = Factor of Safety

Here,


a
= M
a

/ Z

where M
a

is the alternating bending moment and Z is the section Modulus


m
= M
m

/ Z

where M
m

is the mean bending moment and Z is the section Modulus

Z =


d
3

/ 32

and M = w l /4, where w is the load and l is the span of beam.

M
a

= ( M
1



M
2

) / 2 and M
m

= ( M
1

+ M
2

) / 2

For M
1
, use maximum load and for M
2
, use minimum load.


1

FOS


m


u


1

FOS


m


y

Kanpur Institute of Technology

A
-
1, Rooma Industrial Area, Rooma, Kanpur


208 007 (UP) India

Materials Science and Testing Lab (TME


351)

O
bservation :

Diameter of Beam


: ……….…….…….

Load on the beam


: ……….…….…….

Span of the beam


: ……….…………..

No of Cycles at Failure

: ……………………


Calculation :


Result :

The endurance strength for given specimen is ……………..


Precautions :



Load value should
not be change during experiment.



Specimen should be prepared carefully.



Vibration of the machine should be avoided.


Questions for Discussion :



Define Fatigue failure.



What do you mean by fatigue fracture?



What are the methods to prevent fatigue failure?


==========================