[Laboratory Report Cover]
EXPERIMENT 3
HARDNESS TEST
EXPERIMENT DATE:06.10.2017
No
1
Name
VITHYA VEERAPPAN
ID No
SA16075
2
SITI SYAIRAH BINTI IBRISHAM
SA16080
3
NORFAQIHAH NABILAH BINTI ROSLAN
SA16072
Content
Abstract
Introduction
Methodology
Discussion (results)
Conclusion
References
TOTAL
Comments
Signature
Marks
/5
/15
/10
/60
/5
/5
/100
ABSTRACT
From this experiment,we know how to handle the Rockwell Hardness testing machine
and perform the Rockwell hardenss test by using Brass sample,Copper sample and also
Aluminium sample. The Rockwell scale is a hardness scale based on indentation hardness of
a material. The Rockwell test determines the hardness by measuring the depth of penetration
of an indenter under a large load compared to the penetration made by a preload.The
Rockwell hardness test is the most common because it is the most simple to conduct and also
does not require any special skills. In this experiment three samples are given (copper,
aluminum, and brass).Then conducted on each of the samples to get a Rockwell hardness
number.Based on the result that we get the mean of HRA sample are 45.64(Brass),
33.16(Copper) and 35.38(Aluminium).From the data we collect,mybe it will be inaccurate
data due to imperfectation on the surface of the sample.
INTRODUCTION
The earlier method for measuring hardness involved the use of scratch test, in which
the tester determines a material’s resistance to scratching or abrasion by a sequence of
standard objects (Hardness Testing, Volume 19, Issue 11, pp. 76-77)
Hardness is a characteristic of a material, not a fundamental physical property. It is defined
as the resistance to indentation, and it is determined by measuring the permanent depth of the
indentation. More simply put, when using a fixed force (load) and a given indenter, the
smaller the indentation, the harder the material. The principal purpose of the hardness test is
to determine the suitability of a material, or the particular treatment to which the material has
been subjected. The quantitative value of hardness should always be evaluated in relation to:
•
•
•
The type of indenter and its geometry
The given load on the indenter
A specific loading time profile and a specific load duration
The Rockwell hardness test method, as defined in ASTM E-18, is the most commonly
used hardness test method. The Rockwell test is generally easier to perform, and more
accurate than other types of hardness testing methods. The Rockwell test method is used on
all metals, except in condition where the test metal structure or surface conditions would
introduce too much variations; where the indentations would be too large for the application;
or where the sample size or sample shape prohibits its use.
Figure 1: Rockwell Hardness Tester
In addition to a Rockwell Hardness Test, there is a Superficial Rockwell. For each
test, a minor load is applied to either a diamond cone or a steel ball indenter positioned on the
test material’s surface to establish a zero reference position. Next, a major load is applied for
a specified amount of time, leaving the minor load applied upon release. The Rockwell
hardness number will be the difference in depth between the zero reference position and the
indent due to the major load.
The choice of indenter is dependent upon the characteristics of the test material. The
Rockwell Hardness Test applies larger minor and major load values than the Superficial
Rockwell, yet both tests offer three different major load options. More than thirty different
scales are used between Rockwell and Superficial Rockwell hardness testing due to the
various choices and combinations of tests, indenters and major loads.
Figure 2: The depth of indenters that applied to metal
A = Depth reached by indenter after application of preload (minor load)
B = Position of indenter during Total load, Minor plus Major loads
C = Final position reached by indenter after elastic recovery of sample material
D = Distance measurement taken representing difference between preload and major load
position. This distance is used to calculate the Rockwell Hardness Number.
While in industry, for the industrial application Rockwell hardness test is used for
measuring the hardness of the following materials:
•
Cemented carbides, thin steel and shallow hardened steel
•
Copper alloys
•
Aluminium alloys
•
Cast iron
•
Magnesium alloys
OBJECTIVE
•
To study the Rockwell Hardness testing machine and perform the Rockwell hardness
test
METHODOLOGY
•
MATERIALS AND EQUIPMENT
Rockwell Hardness testing machine,Sample (copper looking piece, aluminium looking
piece, brass looking piece)
•
EXPERIMENTAL PROCEDURE
1. The operating instruction of Rockwell 574 hardness testing machine was read
carefully.
2. The Rockwell hardness scale was determined properly.
3. The Rockwell hardness tester was calibrated.
4. The specimen surface was cleaned by removing dust, dirt, oil and grease.
5. Both the specimen surface and the ball was contacted by rotating the jack adjusting
wheel.
6. The required button was pushed for loading.
7. The load release level was pulled and wait for minimum 15 second. The load will
automatically apply gradually.
8. The specimen from support table was removed and the indentation was loacatd.
9. The entire operation is repeated 5 times at different position.
RESULTS
No
1.
2.
3.
4.
5.
MEAN
STDEV
BRASS
46.3
45.8
46.5
44.5
45.1
45.64
91.28
COPPER
33.3
32.9
32.8
33.2
33.6
33.16
66.32
ALUMINIUM
35.2
34.7
35.9
35.8
35.3
35.38
70.76
DISCUSSION
CALCULATION
Formula Of Mean
Sample Brass
=
𝟒𝟔.𝟑+𝟒𝟓.𝟖+𝟒𝟔.𝟓+𝟒𝟒.𝟓+𝟒𝟓.𝟏
𝟓
= 45.64
Sample Copper
=
𝟑𝟑.𝟑+𝟑𝟐.𝟗+𝟑𝟐.𝟖+𝟑𝟑.𝟐+𝟑𝟑.𝟔
𝟓
= 33.16
Sample Aluminium
=
𝟑𝟓.𝟐+𝟑𝟒.𝟕+𝟑𝟓.𝟗+𝟑𝟓.𝟖+𝟑𝟓.𝟑
𝟓
= 35.38
Formula of standard deviation
Sample Brass
=√
(𝟐𝟐𝟖.𝟐−𝟒𝟓.𝟔𝟒)𝟐
𝟒
= 91.28
Sample Copper
(𝟏𝟔𝟓.𝟖−𝟑𝟑.𝟏𝟔)
=√
𝟐
𝟒
= 66.32
Sample Aluminium
=
√(𝟏𝟕𝟔.𝟗−𝟑𝟓.𝟑𝟖)𝟐
= 70.76
𝟒
CONCLUSION
REFERENCES
•
M. C. Shaw and G. J. DeSalvo, (1970). On the Plastic Flow Beneath a Blunt
Axisymmetric Indenter, Trans. ASME. Vol 92 .p480
•
H.N. Jones (Nov 1992) "An Evaluation of the Impression Test for Estimating the
Tensile Properties Of Metallic Materials, Journal of Testing and Evaluation, Vol. 20,
pp. 403-407.
•
Kevin J. Anderson (November 1994) Hardness Testing,Volume 19,Issue 11,
page 76-77
•
S. P . Rockwell. August 1922. The Testing of Metals for Hardness Transaction of the
American Society for Steel Treating. Vol. 11. No. 11. pp. 1013-1033.
•
Harry Chandier,ASM International Publication,Hardness Testing,2nd Eddition,Jan 1
(1999),Page 41-45