The document describes a Jominy end-quench test experiment to measure the hardenability of two steel samples. Steel samples A and C were heated to the austenite temperature and quenched with water at one end. Hardness measurements using the Rockwell C scale were taken at intervals along the samples. Sample A showed little variation in hardness, while hardness decreased with distance from the quenched end for sample C. A graph of hardness versus distance revealed that sample A has higher hardenability, retaining hardness further from the quenched end. The hardenability indices at 50HRC were determined to be 2mm, 5mm, and 6.5mm from the graph.

1. 1
SOKOINE UNIVERSITY OF AGRICULTURE
Collage of Agriculture
DEPARTMENT OF ENGINEERING SCIENCES AND TECHNOLOGY
BSc. IRRIGATION AND WATER RESOURCES ENGINEERING
DOTO, MUSA GESE
IWR/D/2016/0011
MATERIAL TESTING PRACTICAL REPORT
HARDNESS OF STEEL TESTING
JOMINY TEST
Venue: CoET-University of Dar es salaam
Instructor: MR SWANYA
Date of submission: JUNE 2018

2. 2
ABSTRACT
Controlling a material’s properties during processing is pivotal for any engineering field. A specific hardness for a
metal is often a desirable characteristic for many applications, so controlling hardness is important during
processing. To increase the hardness of steel, it is often quenched from a high temperature to form martensite, a
hard yet brittle phase of iron. The extent of martensite formation, including hardness and depth of formation, is
known as hardenability. This practical provides an experiment for measurement of hardenability in plain carbon
steel and an alloyed steel according to, the Jominy End-Quench Test , (ASTM A255 – 10). The demonstration
exercise involve quenching one end of a heated steel sample ,comparing and evaluating the hardness distribution
using measurements obtained at different locations(distance interval) on the sample(specimens) surface.
i

3. 3
TABLE OF CONTENTS
Abstract ……………………………………………………………………………………………………….i
ACKNOWLEDGEMENT…………………………………………………....................................................iii
1. INTRODUCTION……………………………………………………...…………………………………..1
1.1 The aim of the experiment………………………………………………………………………... 1
1.2 Theory of the experiment……………………………………………………………………...…..1
2. EXPERIMENTAL METHODS…………………………………………………………….…………….2
2.1 Equipments used in Jominy Test…. …………………………………………………….………..2
2.2 Specimen …………………………………………………………………….……..……….……,3
3. EXPERIMENTAL PROCEDURE S…………….………………………………………….…………….3
4. RESULTS AND DISCUSSION………………………………………………………………….…….....4
4.1 Results………………………………………………………….……………………………...….4
4.1.1 Table of results…………………………………………………………………………. .4
4.1.2 Graph of Hardness(HRC) against distance(mm) ……………..………………………...4
4.2 Discussion…………………………………………………….………………………………......4
5 ERRORS AND CONCLUSION ……………………………..………………………………………….. 5
5.1 SOURCES OF ERROR………………………………………..…………………………………5
5.2 CONCLUSION …………………………………………………………………………………. 5
REFERENCES............................................................................................................................................. .6
ii

4. 4
ACKNOWLEDGEMENT
I would like to express my grateful appreciation to the practical coordinator of the department of engineering
science and technology at SUA, PROF. LAZARO for providing a conducive economic situation that enabled me
to travel well without any obstacles to UNIVERSITY OF DAR ES SALAAM. Also special thanks are directed to
University of Dar es Salaam management for their kindness for allowing me to conduct my practical at their
university. Last but not least I extend my sincere thanks to MR SWANYA for his valuable contributions and
advices on completion of my STEEL HARDENABILITY practical.
iii

5. 1
1. INTRODUCTION
1.1 The aim of the experiment
The aim of the experiment to study hardness as a function of quench rate and investigate the hardenability of
Two steel , plotting the hardenability chart and use it to estimate the Hardenability index number at 50HRC
in millimeter.
1.2 Theory of experiment
To understand heat treatment of steels requires an understanding of the Fe-C phase diagram shown in
Figure . A steel with 0.76 wt%C is said to be a eutectoid steel. A steel with a carbon content less than 0.76
wt% is hypoeutectoid and greater than 0.76 wt% is hypereutectoid. The region marked austenite (γ) is face-
centered-cubic and ferrite (α) is body-centered-cubic .
The hardenability of a steel is defined as that property which determines the depth and distribution of
hardness induced by quenching from the austenitic condition. The dependence of hardness upon quenching
rate can be understood from the time-temperature-transformation characteristics of steel, and, for particular
steel, can be estimated from the T-T-T diagram.
A part may be hardened by quenching into water, oil, or other suitable medium. The surface of the part is
cooled rapidly, resulting in high hardness, whereas the interior cools more slowly and is not hardened.
Because of the nature of the T-T-T diagram , the hardness does not vary linearly from the outside to the
center. Hardenability refers to capacity of hardening (depth) rather than to maximum attainable hardness.
The hardenability of a steel depends on:
1. The composition of the steel,
2. The austenitic grain size, and
3. The structure of the steel before quenching.
In general ,hardenability increases with carbon content and with alloy content. The most important factor
influencing the maximum hardness that can be obtained is mass of the metal being quenched. In a small
section, the heat is extracted quickly, thus exceeding the critical cooling rate of the specific steel and this
part would thus be completely martensitic. The critical cooling rate is that rate of cooling which must be
exceeded to prevent formation of non-martensite products. As section size increases, it becomes
increasingly difficult to extract the heat fast enough to exceed the critical cooling rate and thus avoid
formation of non-martensitic products. Hardenability of all steels is directly related to critical cooling rates.

6. 2
2. EXPERIMENTAL METHODS
2.1 Equipments and machine used
b) Jominy apparatus
the hardening apparatus which consist of a fixture for supporting and locating centrally the test piece
in its vertical position so that the lower end of the test piece is 12.5mm above the orifice of the water
quenching device. Vertical stream of water that can be controlled to a constant height of 65mm,
without specimen in position, when passing through an orifice of 12.55mm diameter is supplied
b) Scriber
A metal iron with a sharp pointed edge. Which is used in marking line on metal specimen. For this
experiment scriber used in making distance on the steel specimens.
c) Hardness tester machine
The device consist of the main parts, the indention producing system, the load producing system and the
optical system. All the three are mounted in the cast iron u shaped body frame. The machine is the
universal testing machine so when you want to use it you have to first set the type of scale your want to
use. In our case we will set Rockwell C scale hardness test.

7. 3
d) Vernier caliper
It is a measuring device which has two scales which are linear and vernier scale. Its vernier scale has an
accuracy of 0.01mm.It use for measuring diameters and length of the specimen in the experiment. It
was used in measuring distances on the specimen.
2.2 Specimens
Two specimens were shaped according to standards BS 4437 / DIN 50191.the specimen are specimen A
(alloyed steel) and specimen C (unalloyed steel)
3. EXPERIMENTAL PROCEDURES
1. SPECIMEN HEATING
(a) Heating the two specimens up to their Austenite Temperature for 30 minutes.
2. JOMINY TEST MACHINE
(b) The heated test piece were removed from the furnace and then quickly placed in a support so that
its bottom face is 12.5 mm above the orifice.
(c) Water was carefully applied at the specimen’s end splashing of the specimen sides were avoided.
(The time between removal of the test piece from the furnace and the beginning of the quench
shall be not more than 5 seconds) left for 15 minutes.
3. HARDNESS MEASURING
(d) Distances of spacemen which need to be tested were marked to both specimens as shown in the
table of results as shown in the data table.
(e) Placing each specimen to the Hardness testing Machine and the Rockwell C (HRC) hardness in
each interval distance measured as shown in the table of results.
(f) Plotting the hardness measured of each specimen with relation to the distance from end quench
on the same graph.
(g) The hardenability of two curves were compared.

8. 4
4. RESULTS AND DISCUSSION
4.1 Results
4.1.1 Table of results
S/N DISTANCES(mm) SPECIMEN A (HRC) SPECIMEN C (HRC)
1. 2.00 50 59
2. 3.50 57 51
3. 4.25 57 53
4. 5.00 54 50
5. 6.50 55 50
6. 7.25 56 37
7. 9.00 55 36
8. 10.50 57 30
9. 12.00 55 28
10. 15.00 54 26
11. 20.00 56 23
12. 25.00 54 20
4.1.2 GRAPH OF HARDNESS (HRC) VS DISTANCES
4.2 DISCUSSION
From the graph ,specimen A didn’t show much variation in hardness compared to specimen C which
the hardness decreases as leaving away the quenching end of the specimen .It is possible to evaluate
the hardenability indices of the steels used in this experiment using the plotted hardenability
curves at 50HRC which are 2mm ,5mm and 6.5mm.
0
10
20
30
40
50
60
70
2 3.5 4.25 5 6.5 7.25 9 10.5 12 15 20 25
HARDNESS
(HRC)
GRAPH OF HARDNESS (HRC) VS DISTANCES
SPECIMEN A(HRC)
SPECIMEN B(HRC)

9. 5
5. ERRORS AND CONCLUSION
5.1 SOURCES OF ERROR
1. Parallax on measuring the readings from ROCKWELL testing .
5.2 CONCLUSION
Hardness decreases with distance for specimen C from the quenched end because the quenching rate
decreases with this distance, as does also the martensite content. Each steel alloy has its own distinctive
hardenability curve. High hardness occurs where high volume of fractions of martensite develop, lower
hardness indicates transformation to bainite or ferrite and pearlite microstructures. Therefore the results
show that the materials strength is affected by the rate of cooling.The specimen A is hard therefore can be
used to make gears, shaft and heavy bodies.

10. 6
REFERENCE
I.J.Kabyemera,A.Kolasa,E.T.N.Bisanda,laboratory practicals in materials Technology(UDSM),1992
Chandler,(Editor),Hardness Testing, 2nd edition,
Materials science and engineering: an introduction / William D. Callister, Jr. David G. Rethwisch.–8th ed.
Metals Handbook, 9th ed., Mechanical Testing, Vol. 8, 1990.
G. Dieter, Mechanical Metallurgy, SI ed., Mc Graw Hill, 1986.
N. Dowling, Mechanical Behavior of Materials, Prentice Hall, 1993.
ASTM and TS Standards.
ASM Metals Handbook, 9th ed. Vol. 12.