1. Brinell hardness test
Theory related to Brinell hardness
The first widely accepted and standardized indentation test, was proposed by J.A. Brinell in
1900. Brinell hardness test is mostly regarded as destructive test. This test is widely used in
different industries. Brinell hardness test is macro hardness test in which large volume is
displaced by hardened steel or tungsten carbide ball. Brinell hardness number is the hardness
index, calculated by pressing a hardened steel ball (indenter) into test specimen under
standardized load. Brinell hardness tests are used to determine hardness of metallic materials,
to check quality level of products, for uniformity of samples of metals, for uniformity of results
of heat treatment.
The Brinell Hardness Number (BHN) is obtained by dividing the applied force by the spherical
surface area of the indentation,
Equation: BHN formulae
BHN =
applied load in kg
area of impression or
indention in mm2
BHN =
P
Dtπ
Where
P = applied load in kilogram
D = dia of ball used in mm
d = dia of impression produced in mm
t = thickness or depth of impression in mm
Apparatus
 Testing Machine
Equipment for Brinell hardness testing usually consists of a testing machine which supports
the test specimen and applies an indenting force to a ball in contact with the specimen. The
design of the testing machines shall be such that no rocking or lateral movement of the indenter
or specimen occurs while the force is being applied. The design of the testing machine shall
ensure that the force to the indenter shall be applied smoothly and without impact forces.
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2. Brinell hardness test
 Brinell Balls
Table 1 dia and tolerance of Brinell hardness ball
Sr. no
Ball dia, mm
Tolerance, mm
1
10
±0.005
2
5
±0004
3
2.5
±0.003
4
2
±0.003
5
1
±0.003
 Measuring Device
The divisions of the micro meter scale of the microscope or other measuring devices used for
the measurement of the diameter of the indentations shall be such as to permit the direct
measuring of the diameter to 0.1 mm and the estimation of the diameter to 0.05 mm.
Figure 1 Brinell hardness machine
Figure 2 Brinell hardness ball
Test Specimen
There is no standard shape or size for a Brinell test specimen. The specimen upon which the
indentation is made shall conform to the following:
Thickness
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3. Brinell hardness test
The thickness of the specimen tested shall be such that no bulge or other marking showing the
effect of the test force appears on the side of the piece opposite the indentation. As a general
rule, the thickness of the specimen shall be at least ten times the depth of the indentation
Finish
When necessary, the surface on which the indentation is to be made shall be filed, ground,
machined or polished with abrasive material so that the edge of the indentation shall be clearly
defined to permit the measurement of the diameter to the specified accuracy.
Test procedure
We were provided steel sample which were heat treated. Rough grinding is done with zero
ambry paper. After rough grinding sample was checked either its or thickness and surfaces are
flat. Than sample was placed over anvil and adjusted anvil. A steel hardened ball of 10mm dia
is used. Applied the load of 3000kg for 10 seconds. Removed the load an impression has been
made. Measure the dia of impression with low magnification microscope.
Calculation
1st experiment
Dia of steel hardened = 10mm
Dia of impression = 4.7mm
Load applied = 3000kg
Dwell time = 10 sec
BHN = 163.3 kgf/mm2
2nd experiment
Dia of steel hardened = 10mm
Dia of impression = 4.65mm
Load applied = 3000kg
Dwell time = 10 sec
BHN = 166.59 kgf/mm2
Advantages of Brinell hardness

Suitable for hardness tests even under rough workshop conditions.

Suitable for hardness tests on inhomogeneous materials.

Simple test procedure.

Simple and cheap penetration element.

Conversion into tensile strength for various materials.
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4. Brinell hardness test

Nearly All Metals Can Be Tested.

The Brinell Tests a Wider Sample of Material.

Results of the Brinell Test are Force Independent.
Disadvantages of Brinell hardness

Restriction of application range to a maximum Brinell hardness of 650 HBW.

Restriction when testing small and thin-walled specimens.

Restriction when testing round specimen if diameter is smaller then 1, 5 x penetrator
diameter.

Relatively serious damage to the specimen due to the large test indentation.
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5. Brinell hardness test
References
 http://hardnesstesting.info/brinell05.html
 http://www.ehow.com/list_7273906_advantages-brinell-hardness
test.html#ixzz2gH4HMaSx
 E10-01E1 - Brinell Hardness of Metallic Materials
 http://www.academia.edu/2158292/Brinell_Hardness_Test_determination_of_hardnes
s_of_steel_and_aluminum
 http://www.instron.us/wa/applications/test_types/hardness/brinell.aspx
 Mechanical metallurgy by dieter
 Materials science and engineering by William D Callister Jr eighth edition
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