Lab Report 1
LAB 1: BRINELL HARDNESS TEST
Performed on May 14th, 2024
By
MD Farhan Tusher (40207306)
ENGR 244
Section AK-X
Summer 2024
Concordia University
Montreal, QC, Canada
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Table of Contents
Objective…………………………………………………………………………………………………...3
Introduction………………………………………………………………………………………………..3
Procedure…………………………………………………………………………………………………..4
Results……………………………………………………………………………………………………4,5
Discussion………………………………………………………………………………………………...5,6
Appendix…………………………………………………………………………………………………...7
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Objective
The aim of this lab experiment is to comprehend the resistance to permanent indentation of various metals
under static or dynamic loads.
Introduction
Materials play a crucial role in Engineering since they are constantly subjected to stress over extended
periods. Given that these materials support large infrastructures, it is essential to understand their behavior
under various forces, as they can deform or break if exposed to their ultimate tensile strength. Engineers
place a high priority on selecting the right materials, as these form the foundation of their structures,
making the selection process critical.
Materials are designed to endure significant strength or loads, and their ability to do so depends on their
type. The extent to which a material can withstand force and the impact of that force are critical factors.
Loads can cause permanent deformation if the stress exceeds a material's capacity. Every material has an
elastic limit, within which it can return to its original shape after deformation. However, when stress
surpasses this limit, permanent deformation or even fracture can occur. This is the fundamental behavior
of materials under stress.
With advancements, new materials with enhanced strength and durability are continuously introduced to
meet specific application requirements. Therefore, identifying the most suitable materials for specific
tasks becomes increasingly important. The Brinell hardness test assists in this process. This test uses a
steel ball as the indenter. The indentation is created by pressing the steel ball smoothly into a flat surface
of steel or aluminium disc under a known load, maintained for 15 seconds. The hardness is then
calculated as the load in kilograms divided by the curved area of the indentation in square millimeters.
This experiment enables us to quantify the extent of permanent indentation produced by applying a
specific load to a particular material.
Equipment required to conduct this experiment are as follows:
- Compression machine
- Steel/aluminium ball of 10.00mm diameter
- Microscope (0.02mm)
- Steel and aluminium flat discs with finished surfaces
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Procedure
The same procedure will be followed for both metal discs, except for the variation in the applied load.
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The handle of the compression machine is lowered until the digital meter reading reaches zero.
One of the metal discs is placed on the compression machine's plate, ensuring that the pointer is
not centered on the ball, as multiple readings will be taken.
The lever on the compression machine's side is lowered to raise the plate, bringing the metal disc
closer to the pointer.
The hydraulic pump handle is pulled upward to apply the load (10,000N for steel and 5,000 for
aluminium) until the desired value appears on the digital meter and maintained for 15 seconds to
stabilize.
The load is then noted down and then the lever is pushed downwards to take out the metal ball.
The metal disc is then taken out and with the use of the microscope, the diameter of the
indentation is measured and noted down.
The experiment is repeated two more times for the same metal disc, applying the same load on
the same surface but in different positions to calculate the average.
Results
Sample
No.
of
trials
dx(mm)
dy(mm)
davg(mm)
Load,
P(Kg)
Depth of
indentation,
t(mm)
Area of
indentation,
A(mm2)
Brinell
Hardness,
HB(Kg/mm2)
Average
Brinell
Hardness,
HBavg(Kg/mm2)
Steel
1
2.95
3.0
2.975
1041.02
0.226
7.1
146.62
153.13
2
2.8
2.9
2.85
1043.83
0.207
6.5
160.59
3
2.95
2.9
2.925
1050.05
0.219
6.9
152.18
1
2.3
2.45
2.375
524.77
0.143
4.5
116.2
2
2.35
2.25
2.3
518.86
0.134
4.2
123.54
3
2.4
2.3
2.35
515.90
0.140
4.4
117.25
Aluminium
118.99
Table 1: Data obtained from the experiment
For each test, the Brinell Hardness (HB) is calculated using the formula:
𝐻𝐵 =
𝑃 (𝑘𝑔)
𝐴 (𝑚𝑚2 )
Where:
P = applied load in kg
A = Area of indentation = πDt = [(πD/2)(D-(D2 – d2)0.5]
D = diameter of the ball in mm
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d = mean diameter of the impression in mm
t = depth of indentation in mm
The result gives us the average Brinell Hardness (HB) for the two discs used in the experiment, where a
specific load was applied, and the diameter of the indentation was measured. The HB formula was used to
calculate the stress, and the values used for the calculations are provided in the appendix. To enhance the
accuracy of the results, the experiment was repeated three times and conducted by three engineering
students, ensuring maximum precision. As a result, all three sets of values are extremely close to one
another.
Discussion
1. In engineering, material selection is crucial, and this experiment provides valuable and sufficient
information on a material’s mechanical properties, aiding engineers in making decisions
regarding material selection, quality control, and sustainability for specific applications. For
example:
- Heat Treatment Monitoring: During the heat treatment process, hardness testing is used to
monitor and control the hardness of the treated material, which is essential for achieving the
desired mechanical properties in components.
- Welding Quality Assessment: Hardness testing is employed to evaluate the quality of welds,
ensuring that welded joints have consistent hardness.
- Aerospace Industry: In this field, materials are subjected to extreme conditions, making hardness
testing critical.
2. Other hardness tests used in engineering include:
- Vickers Hardness Test: Uses a diamond-shaped indenter to create an indentation with a square
base.
- Knoop Hardness Test: Provides high-resolution measurements for small and delicate samples,
making it ideal for microhardness testing.
- Shore Hardness Test: Quantifies a material's resistance to a blunt point being pressed into it,
commonly used for plastics and elastomers.
- Rockwell Hardness Test: Measures the difference in indentation depth between a major and minor
load.
3. Effects of experimental errors on the Brinell hardness number.
a. If the indentations were positioned too close to the edge:
- There is a risk of the metal ball slipping away and causing injury to someone.
- The results may vary as the hardness near the edge may differ from that of the bulk material.
- If the material is brittle, it may fracture if indentations are too close to the edge.
b. If the indentations were positioned too close to each other:
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- Overlapping could occur, making it challenging to take accurate measurements.
- High-density indentations could induce small cracks in the material.
4. Potential errors include:
- Equipment Calibration: Inaccurate results may occur if the testing equipment is not regularly
calibrated.
- Load Application: Human manual application of load can lead to errors, as it's challenging to
uniformly increase the load over time.
- Parallax Error: Even a slight tilt of the head can cause the operator to perceive a different, irrelevant
value without realizing the mistake.
- Insufficient Light: Proper lighting is essential for operators to accurately read measurements through
the microscope.
- Surface Condition: If the load is not applied to a flat surface, the resulting indentations may be
inaccurate.
Conclusion
The experiment underscored the significance of material quality for various applications, offering
valuable insights into the hardness characteristics of the material under standardized conditions. This
information is essential for material engineers and manufacturers when selecting materials for
applications where hardness plays a critical role. The experiment demonstrated good reproducibility,
as consistent results were obtained across multiple trials. The Brinell Hardness Test was employed to
test and calculate the hardness of aluminum and steel. The obtained hardness values closely aligned
with the published hardness values. Consistent with expectations, steel exhibited higher hardness
compared to aluminum. Despite applying double the force to steel, its indentation diameter was only a
bit larger than that of aluminum.
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Appendix
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