EXPARIMENT NO.

10
DETERMINE THE BRINELL HARDNESS NUMBER OF VARIOUS SPECIMEN

THEORY
BRINELL HARDNESS TEST METHOD:
The Brinell Hardness Test is a method used to measure the hardness of materials, especially metals and
alloys. It involves pressing a hardened steel or carbide spherical indenter into the surface of the material
under a specified load. The size of the indentation left by the indenter is then measured to determine the
hardness of the material. The test is particularly useful for materials with coarse or heterogeneous structures,
like castings or forgings.

Equipment Used in the Brinell Hardness Test:

1. Indenter:


The indenter used in the Brinell test is typically a hardened steel ball or tungsten carbide
ball.
 The diameter of the indenter is a critical factor and is usually between 1 mm and 10 mm,
depending on the material being tested and the required test conditions.
 The indenter is pressed into the material under a predetermined load to create an indentation.
2. Load:


A specific load (force) is applied to the indenter during the test.

The load varies depending on the material being tested and the indenter size. Common loads
are 500, 1000, 1500, or 3000 kgf.
 The load is applied for a set duration, typically 10–30 seconds, to allow for a stable
indentation to form.
3. Machine Setup:

 The Brinell hardness testing machine consists of a loading mechanism, which applies the
load, and a mechanical or digital system to measure the diameter of the resulting
indentation.
 The specimen is positioned under the indenter, and the machine controls the application of
the load and the measurement of the indentation size.
 The machine may also be equipped with a microscope to accurately measure the diameter of
the indentation for smaller diameters.
Types of Materials Tested:
The Brinell Hardness Test is suitable for a wide variety of materials, including:
1. Metals:


The test is commonly used for ferrous (e.g., steel, cast iron) and non-ferrous metals (e.g.,
aluminum, copper, brass).
 The method is effective for materials with coarse grain structures or non-homogeneous
microstructures.
2. Alloys:


Metal alloys, such as steel alloys, bronze, and brass, can be tested using the Brinell method.
It is especially useful for testing materials that are difficult to evaluate with other methods
due to their heterogeneous structure.
3. Composites:
  Brinell hardness testing can also be used for certain composite materials like polymer-based
composites or reinforced concrete. However, the accuracy of the test may vary based on the
material's composition and structure.
Principle of the Brinell Hardness Test:
The principle of the Brinell hardness test is based on the concept of plastic deformation caused by the
indentation of a spherical indenter under a known load. The key steps are:
 Application of Load: A known load (P) is applied to a spherical indenter (of
known diameter, typically 10 mm) for a predetermined time (usually 10–30
seconds).
 Indentation Formation: As the load is applied, the indenter presses into the
material, causing a permanent indentation. The size of the indentation depends
on the hardness of the material; harder materials produce smaller indentations,
while softer materials produce larger indentations.
 Measurement of Indentation Size: After the load is removed, the diameter
of the resulting indentation is measured. This is typically done using a
microscope or automated imaging system. The larger the indentation, the softer
the material.
 Calculation of Brinell Hardness Number (BHN):
 The Brinell Hardness Number (BHN) is calculated using the following
formula:
2P
BHN =
πD ( D− √ D −d )
2 2

Where:

 P = applied load (in kilograms),

 D = diameter of the indenter (in millimeters),
 d = diameter of the indentation (in millimeters).
 The resulting BHN value indicates the material's hardness. A higher BHN
corresponds to a harder material.

The Brinell test is particularly useful for materials with coarse or uneven structures, where other hardness
tests like Rockwell might be less accurate. The larger indenter and load ensure that the test can penetrate and
give a meaningful result for such materials.

Factor Effect
Material Type Heterogeneous materials show inconsistent hardness readings; homogeneous materials
give more reliable results.
Surface Oxidation, corrosion, coatings, and contaminants can alter the indentation, leading to
Condition inaccurate results.
Indenter Size Larger indenters are better for soft materials, while smaller indenters are better for
harder materials.
Applied Load Higher loads create deeper indentations; too high a load can distort the material, while
too low a load may not create enough deformation.
Surface Rough surfaces affect the indentation shape, leading to measurement inaccuracies.
Roughness
Sample Poor preparation (e.g., rough, uneven surfaces) can distort the indentation and make
Preparation measurement difficult. Proper grinding and polishing are required for accurate results.
Material
Behavior Brinell Test Rockwell Test
Soft Materials Large, clear indent; useful for measuring Can deform too much, making it hard
grainy or inconsistent textures to get accurate depth
Hard Indenter may flatten or not create a visible Excellent for hard materials using the
Materials indent diamond cone
Ductile Good representation of plastic flow May give inconsistent readings due to
Materials recovery
Brittle Risk of cracking around the indent Small load helps avoid cracking
Materials

APPLICATIONS OF BRINELL HARDNESS TEST

The Brinell hardness test is widely used across industries and research fields for
evaluating the hardness of various materials, particularly metals and alloys. Here are
some of the key applications:

1. Metal and Alloy Testing

 Casting and Forging: Brinell is commonly used to test cast and forged
metals because of its ability to handle coarse-grained structures. Castings,
which often have varying levels of hardness due to their irregular
microstructures, benefit from Brinell's ability to average the hardness over a
larger area.
 Alloy Development: It’s used in alloy research to evaluate the hardness of
different metallic mixtures. For instance, in developing new steel alloys,
Brinell testing helps determine the hardness of various compositions under
different cooling and heat treatment processes.

2. Evaluation of Material Properties

 Hardness Profiling: In material science and manufacturing, Brinell

hardness testing is useful for creating hardness profiles of materials to
understand their resistance to indentation and wear.
 Quality Control: During production, Brinell hardness tests are used to
ensure that metals and alloys meet the required hardness standards. This is
particularly critical in industries where material strength and durability are
key factors, such as automotive or aerospace industries.

3. Testing of Industrial Components

 Large Steel Parts: Brinell testing is employed for testing large or thick
parts, such as gears, shafts, and rolls, in industries like mining and steel
manufacturing. It is particularly effective for materials that are too thick or
large to use other hardness tests, like the Rockwell method.
 Wear Resistance Studies: The Brinell hardness test is used to evaluate the
wear resistance of industrial components such as machine parts, bearings,
and molds, helping to predict their lifespan and suitability for specific tasks.
4. Research and Development

 Material Comparison: Researchers use Brinell to compare the hardness of

different materials, such as metals, ceramics, and composites. It helps in
developing new materials for applications where wear resistance is essential.
 Heat Treatment Studies: The Brinell test is useful for studying how various
heat treatment processes, such as annealing, quenching, or tempering,
affect the hardness of a material. This helps in optimizing processing
techniques to achieve desired material properties.

5. Geological and Mining Applications

 Rock and Mineral Testing: In mining, the Brinell test is sometimes adapted
to measure the hardness of rocks and minerals. It is useful in determining the
abrasiveness of rocks and how they will wear down mining equipment like
drills and crushers.

6. Engineering and Mechanical Testing

 Fabrication Process Control: Brinell hardness testing is employed in the

control of fabrication processes like welding, where it can be used to assess
the hardness of welded joints or heat-affected zones to ensure they meet the
required mechanical properties.
 Automotive Industry: Used to evaluate the hardness of engine
components, such as pistons, valves, and camshafts, ensuring that they
meet the required durability and strength standards for long-term
performance.

APPRATUS
Brinell hardness tester

Microscope

Ball intender

PROCEDURE
 Clean the surface of anvil table from dust particles and oil/grease to remove
slippage.
 Clean the surface of indenter from dust particles.
 Insert the indenter of 10mm diameter in the split chuck.
 Apply load of kg on the specimen through indenter.
 Selection of load depends on the scale that we choose to perform.
 Keep the load applied for dwell time of 10 seconds and then remove the load.
 Measure the diameter of the indentation produced by microscope.

Observations
 Least count of microscope scale = 0.05mm
 Diameter of indenter = D =10mm

Table and Datasheet

No. of Load applied P Indentation Indentation B.H.N =

Obs. (kg) Diameter d (mm) Depth P/π (D*t)
t = [D-(D2-
d2)1/2]/2 (mm)
1 500 5 0.670 23.78
2 500 4.9 0.641 24.82
3 500 5.1 0.699 22.76
Average BHN= 23.78