Steel 4140Left MiddleRight AVGHardness (HRA)42.7.docx

Steel 4140
Left
Middle
Right
AVG
Hardness (HRA)
42.7
48.4
45.2
45.4
Diameter (in.)
0.996
0.994
0.995
0.995
Steel 1410
Left
Middle
Right
AVG
Hardness (HRA)
46.7
44.4
51.8
47.6
Diameter (in.)
0.994
0.995
0.995
0.995

Steel 1410 Rockwell A (HRA) Measurements
Every 1/16 inch for 1 inch
Every 1/4 inch for 2 inches
1
23.0
45.9
41.9
2
45.7
47.1
42.0
3
47.8
46.6
40.9
4
46.0
44.9
29.5
5
46.0
46.7
32.7
6
45.1
47.5
42.5
7
47.1
45.3
43.0
8
46.9

43.3
21.8
9
45.2
10
47.7
11
47.8
12
46.9
13
46.8
14
55.8
15
45.9
16
46.6

Steel 4140 Rockwell A (HRA) Measurements
Every 1/4 inch for 2 inches
1
69.8
60.3
57.5
2
73.2
61.4
55.4
3
72.2
59.4
51.2
4
72.4
60.1
57.7
5
72.0
58.1
53.2
6
73.2
58.3
72.5
7

73.1
59.7
64.2
8
72.0
58.7
63.7
9
70.5
10
69.1
11
67.7
12
67.4
13
65.4
14
63.2
15
62.1
16

63.2
EXPERIMENT 6
HEAT TREATMENT OF STEEL
Purpose
The purposes of this experiment are to:
Background
To understand heat treatment of steels requires an ability to
understand the Fe-C phase
diagram shown in Figure 6-1. Steel with a 0.78 wt% C is said
to be a eutectoid steel. Steel
with carbon content less than 0.78 wt% C is hypoeutectoid and
greater than 0.78 wt% C is
hypereutectoid. The region marked austenite is face-centered-
cubic (FCC) and ferrite is

body-centered-cubic (BCC).
There are also regions that have two phases. If one cools a
hypoeutectoid steel from a point in
the austenite region, reaching the A3 line, ferrite will form from
the austenite. This ferrite is
called proeutectoid ferrite. When A1 is reached, a mixture of
ferrite and iron carbide
(cementite) forms from the remaining austenite. The
microstructure of a hypoeutectoid steel
upon cooling would contain proeutectoid ferrite plus pearlite
The size, type and distribution of phases present can be altered
by not waiting for
thermodynamic equilibrium. Steels are often cooled so rapidly
that metastable phases appear.
One such phase is martensite, which is a body-centered
tetragonal (BCT) phase and forms
only by very rapid cooling.
Much of the information on non-equilibrium distribution, size
and type of phases has come
from experiments. The results are presented in a time-
temperature-transformation (TTT)

diagram shown in Figure 6-2. As a sample is cooled, the
temperature will decrease as shown
in curve #1. At point A, pearlite (a mixture of ferrite and
cementite) will start to form from
austenite. At the time and temperature associated with point B,
the austenite will have
completely transformed to pearlite. There are many possible
paths through the pearlite
regions. Slower cooling causes coarse Pearlite, while fast
cooling causes fine pearlite to form.
Cooling can produce other phases. If a specimen were cooled at
a rate corresponding to curve
#2 in Figure 6-3, martensite, instead of Pearlite, would begin to
form at Ms temperature (point
C), and the pearlite would be completely transformed to
martensite at temperature Ms.
Martensite causes increased hardness in steels.

Unfortunately, hardness in steels also produces brittleness. The
brittleness is usually
associated with low impact energy and low toughness. To
restore some of the toughness and
impact properties it is frequently necessary to "temper" or
"draw" the steels. This is
accomplished by heating the steel to a temperature between
500ºF (260ºC) and 1000ºF (540ºC).
Tempering removes some of the internal stresses and introduces
recovery processes in the
steel without a large decrease in hardness or strength.
To obtain the desired mechanical properties it is necessary to
cool steel from the proper
temperature at the proper rates and temper them at the proper
temperature and time.
Isothermal transformation diagrams for SAE 1045 steel are
shown in Figure 6-4.
Heat Treatment of Steels

Common steels, which are really solid solutions of carbon in
iron, are body-centered-cubic.
However, the carbon has a low solubility in bcc iron and
precipitates as iron carbide when
steel is cooled from 1600ºF (870ºC). The processes of
precipitation can be altered by adjusting
the cooling rate. This changes the distribution and size of the
carbide which forms a laminar
structure called pearlite during slow cooling processes.
If a steel is quenched into water or oil from 1600ºF (870ºC) a
metastable phase called
martensite forms, which is body-centered-tetragonal. This
phase sets up large internal stresses
and prevents carbide from forming. The internal stresses
produce a high hardness and
unfortunately, low toughness. After cooling, to restore
toughness, steels are tempered by
reheating them to a lower temperature around 800ºF (426ºC)
and cooling. The tempering
relieves the internal stresses and also allows some iron carbide
to form. It also restores
ductility.

Procedure
You are provided with 6 specimens of SAE 1045 steel for your
study. Measure the
hardness of all specimens using the RA scale.
1. Heat four specimens in one furnace at 1600 + 25ºF (870 +
15ºC) for 1/2 hour.
2. Put the other 2 specimens in a separate furnace at the same
temperature for 1/2 hour.
3. Remove one specimen from the furnace with 2 specimens and
cool it in air on a brick.
4. Turn off the furnace with the one remaining specimen. Allow
the sample to remain in
the furnace for one hour. The air-cooled and furnace-cooled
specimens can be cooled
in water after one hour. Why? (Answer this in your write up).
5. Remove the four specimens and quickly drop them into
water; the transfer should take
less than one second. A little rehearsal could help. Be careful
not to touch the
specimens before they are cooled in water.

6. Measure Rockwell hardness of the quenched specimens
before the next step.
7. Temper 1 each of the quenched specimens for 30 minutes at
600ºF (315ºC), 800ºF
(430ºC), and 1000ºF (540ºC). After tempering, the specimens
can be cooled in water.
8. Measure hardness of all 6 samples using the Brinell (3000
kg) and Rockwell A or C
scales.
Data Analysis
1. If more than one impression is made per sample, average the
Brinell diameters for each
specimen.
2. Compute the Brinell hardness numbers and compare with the
numbers read from a
conversion chart for Rockwell A or C to Brinell.
3. Graph BHN (x-axis) versus Rockwell Hardness numbers (y-
axis).
4. Graph Rockwell A or C hardness vs. tempering temperature
(oC).
5. Compute the ultimate tensile strength (psi) of all specimens
from the average BHN for

each specimen using:
Write Up
Prepare a single memo report in conjunction with experiment #7
(Hardenability of
Steels). The report should combine both experiments in one
report. Do not write this up
as a two part report. (The hardness and hardenability concepts
from the experiments are
related). Within this report you should discuss the data
referenced in the "Data Analysis" as
well as the following:
1. What is the purpose of quenching and tempering steel?
2. Discuss the sources of error for the various hardness testers,
the relative ease with which
they may be used, and the comparative consistency of test
results.
3. What factors probably contributed to the scatter in the
hardness data?
4. Which hardness test appears to be most accurate?
5. Using the inverse lever law, estimate the amount of carbide
(Fe3C) present at 1338

oF
(just below the eutectoid temperature) for SAE 1045.
6. What are (or should be) the differences in the microstructure
for each heat treatment
process and how do these differences correlate with hardness?
7. Discuss errors in this experiment and their sources.
MSE 227L Name ________________________
Heat Treatment of steel & Hardenability
Poor Fair Average Good Excellent
Memorandum Format Used 1 2 3 4 5
Spelling, grammar & punctuation correct 1 2 3 4 5
Report includes: Poor Fair Average Good Excellent
Discuss why the air-cooled and furnace-cooled specimens
can be quenched in water after one hour.
1 2 3 4 5
Compare Brinell numbers (BHN) found from measured
diameters with a conversion chart for Rockwell A or C

(6 specimens). Go to website or reference book to find
this information; include this data in your tables.
1 2 3 4 5
Include tables (results and data measured) for BHN and
RA. Be sure to include measured values from computer.
1 2 3 4 5
Graph BHN (x-axis) vs. Rockwell A or C (y-axis). 2 4 6 8 10
Graph Rockwell A or C (y-axis) hardness vs. tempering
temp.
2 4 6 8 10
pecimens from the average BHN
for each specimen.
1 2 3 4 5
Discuss the purpose of quenching and tempering steel. 1 2 3 4 5
Discuss the sources of error for the various hardness
testers; compare consistency of test results and accuracy
(Rockwell vs Brinell).
1 2 3 4 5
Discuss factors that probably contributed to the scatter in

the hardness data and errors in the experiment (their
sources)
1 2 3 4 5
Calculate amount of carbide (Fe3C) present at 1338
o
F for
SAE 1045. Use the phase diagram included in the lab
description and show calculations.
1 2 3 4 5
Discuss the expected microstructure for each heat
treatment process (specifically for the 6 samples).
1 2 3 4 5
Discuss the correlation between microstructure and
hardness.
1 2 3 4 5
Graph hardness as a function of distance from the
quenched end (show both alloys on the same graph).
3 6 9 12 15
Discuss the effects of alloying on hardenability and the
shift in the TTT curve due to alloying.
1 2 3 4 5

Poor Fair Average Good Excellent
Overall level of effort apparent 1 2 3 4 5
Quality of graphs 1 2 3 4 5
Quality of Abstract 1 2 3 4 5
Quality of work description 1 2 3 4 5
Quality of conclusions 1 2 3 4 5
Glossary of Terms
Understanding the following terms will aid in understanding
this experiment.
Austenite. Face-
Austenitizing. Temperature where homogeneous austenite can
form. Austenitizing is the first step in
most of the heat treatments for steel and cast irons.
Annealing (steel). A heat treatment used to produce a soft,

coarse pearlite in a steel by austenitizing,
then furnace cooling.
Bainite. A two-phase micro-constituent, containing a fine
needle-like microstructure of ferrite and
cementite that forms in steels that are isothermally transformed
at relatively low temperatures.
Body-centered cubic. Common atomic arrangement for metals
consisting of eight atoms sitting on
the corners of a cube and a ninth atom at the cubes center.
Cementite. The hard brittle intermetallic compound Fe3C that
when properly dispersed provides the
strengthening in steels.
Eutectoid. A three-phase reaction in which one solid phase
transforms to two different solid phases.
Face-centered cubic. Common atomic arrangement for metals
consisting of eight atoms sitting on
the corners of a cube and six additional atoms sitting in the
center of each face of the cube.
Ferrite. Ferrous alloy based on the bcc structure of pure iron at

room temperature.
Hypereutectoid. Composition greater than that of the eutectoid.
Hypoeutectoid. Composition less than that of the eutectoid.
Martensite. The metastable iron-carbon solid solution phase
with an acicular, or needle like,
microstructure produced by a diffusionless transformation
associated with the quenching of austenite.
Normalizing. A simple heat treatment obtained by austenitizing
and air cooling to produce a fine
pearlite structure.
Pearlite. A two-phase lamellar micro-constituent, containing
ferrite and cementite, that forms in steels
that are cooled in a normal fashion or are isothermally
transformed at relatively high temperatures.
Tempered martensite. The mixture of ferrite and cementite
formed when martensite is tempered.
Tempering. A low-temperature heat treatment used to reduce
the hardness of martensite by permitting

the martensite to begin to decompose to the equilibrium phases.
References
D. Callister Jr, Fundamentals of Materials Science and
Engineering, J. Wiley & Sons, NY, 3rd Ed. 2008,
Flinn and Trojan, Engineering Materials and Their Applications,
Chapter 6
Deiter, Mechanical Metallurgy
ASM Handbook on Heat Treatment, Vol. 2
MAE 2165: Materials Science Lab
Spring 2017
ENGR 116
Prerequisites: MAE 2160 (may be take concurrently)
Textbook: Required: Lab Instructions; The theoretical
foundation for the lab will be covered in MAE 2160 text.
Course Fee: $50 (Course fee used to purchase materials,
supplies, equipment, and fund teaching assistants)
Professor: Jackson Graham

Office: EL 286
Office Hours: W 11:00 AM – 12:00 PM or by appointment
E-mail: [email protected]
Course Description: This lab will allow engineering students to
study the mechanical and thermal properties of metals,
polymers, ceramics, and composite materials. Emphasis is upon
laboratory technique, presentation of experimental
results, evaluation of experimental results, and observation of
the physical phenomena.
Course Objectives: Upon completion of this course, students
should be able to:
1. Execute laboratory techniques and procedures
2. Evaluate experimental results, and
3. Professionally present experimental results.
Topics Covered:
1. General Lab Safety
2. Computational Material Science
3. Tensile Testing
4. Glass Fracture
5. Phase Diagrams

6. Age-Hardening of Aluminum
7. Hardenability of Steels
8. Mechanical Properties of Polymeric Materials
9. Composites
Attendance and Communication Policy: Attendance is required
during the assigned lab period. You are responsible for
any and all information contained in or communicated through
Canvas. You are expected to ensure that you will receive
any communications sent to you though Canvas in a timely
manner. To make up an assignment, or exam, a student will
need a physicians’s note attesting to the illness. No other
excuses will be accepted for making up late work (i.e. vacation,
leisure, community service, oversleeping, forgot to come to
class, getting married, car broke down, research, work, family
time, etc…).
Pre-Labs and Lab Reports: You are required to read the lab and
complete the prelab material PRIOR to the lab period.
Lab reports, including text, figures, tables, and any other
elements, are to be completed INDIVIDUALLY. Lab reports are
required for each lab session. The lab reports will be turned in
at the beginning of the following lab session or via
Canvas prior to the start of the following lab session. Lab
reports will be graded based on the guidelines specified for
the lab and any rubrics provided. A 25% reduction in credit will
be given for assignments up to 24 hours late. No credit
will be given for home works and projects that are more than 24
hours late. You may receive help from others when
doing in-class assignments and homework but you must only
turn in your own work. All work will be completed or

submitted on Canvas.
Grading: The lab reports will be graded according to the
requirements included with each lab. Each lab report will be
due at the time of your arrival to complete the next lab
experiment. Grades will be assigned based on the quality of
your work. NOT the effort you put into it. All requests for
regrading assignments must be made within 7 calendar days
mailto:[email protected]
of the return of the assignment.
The following grading scale will be used in this course:
100 to 94 A
< 94 to 90 A-
< 90 to 87 B+
< 87 to 84 B
< 84 to 80 B-
< 80 to 77 C+
< 77 to 74 C
< 74 to 70 C-
< 70 to 67 D+

< 67 to 64 D
< 64 to 61 D-
< 61 to 0 F
Academic Standards: Cheating and plagiarism are serious
academic offences and will be handled by following the
University policy. At a minimum, a grade of zero will be assign
for the entire assignment or exam. A description of the
USU academic honor system can be found at the following
website:
https://studentconduct.usu.edu/studentcode/article6
The College of Engineering has an Engineering Tutoring
Center. Tutoring services are available free of charge to all
College of Engineering students. You can find help for any
engineering required course, i.e. math, chemistry, physics, and
all engineering classes. The Tutoring Center is located in
ENGR 322 and 324. Hours are Monday through Friday 8:00
AM
to 5:00 PM with extended hours on Tuesday and Thursday until
7:00 PM.
https://studentconduct.usu.edu/studentcode/article6

Tentative Schedule: The weekly experiments are subject to
change based on the availability of equipment and materials.
After the microscopy lab, each lab time
will be split into two groups (“A” and “B”). These two groups
will alternate weeks as shown for the remainder of the semester.
As a reminder, lab reports are due
at the beginning of the next session assigned to your section
AND group.
Lab Week/Dates Group(s) Prelab Lab Assignment Report Due
1: Safety 1: Jan 9 - 13 All Safety N/A N/A
2: Computational Materials 2: Jan 16 - 20 All N/A
Computational Materials N/A
3: Microscopy 3: Jan 23 - 27 All Microscopy Microscopy
Computational Materials
4: Tensile Test and Torsion Fatigue 4: Jan 30 - Feb 3 A Tensile
Test and Torsion Fatigue Tensile Test and Torsion Fatigue N/A
4: Tensile Test and Torsion Fatigue 5: Feb 6 - 10 B Tensile Test
and Torsion Fatigue Tensile Test and Torsion Fatigue N/A
5: Phase Transformation 6: Feb 13 - 17 A Phase Transformation
Phase Transformation Tensile Test and Torsion Fatigue
No Lab 7: Feb 20 - 24 All N/A N/A N/A
5: Phase Transformation 8: Feb 27 - Mar 3 B Phase
Transformation Phase Transformation Tensile Test and Torsion
Fatigue
Spring Break 9: Mar 6 - 10 All N/A N/A N/A
6: Hardenability and Composite
Fabrication
10: Mar 13 - 17 A

Hardenability and Composite
Fabrication
Fabrication
Phase Transformation
6: Hardenability and Composite
Fabrication
11: Mar 20 - 24 B
Fabrication
Fabrication
Phase Transformation
7: Age Hardening and Glass
Fracture
12: Mar 27 - 31 A
Age Hardening and Glass
Fracture
Fracture
Fabrication
7: Age Hardening and Glass
Fracture

13: Apr 3 - 7 B
Fracture
Fracture
Fabrication
8: Polymers and Composite Testing 14: Apr 10 - 14 A N/A
Polymers and Composite Testing
Fracture
8: Polymers and Composite Testing 15: Apr 17 - 21 B N/A
Polymers and Composite Testing
Fracture
16: Apr 24 - 28 All N/A N/A Polymers and Composite Testing
The Memorandum Report
1. Name
Lab Time: (for example, Tuesday or Wednesday 2:00 PM)
Lab Group (1-4)
MSE 227 Lab # (2, 4, 6 & 7, 8, 9) – Title of report
2. Abstract
Similar to a summary, helps a busy reader decide whether to

read the whole report. Since the abstract
gives a thumbnail sketch of the report, an abstract of a memo-
report should run no longer than half a
page; frequently one paragraph describing the entire report (100
words or less) will suffice. Also the
abstract should indicate the conclusions (results) of the work so
that the reader will be able to evaluate the
relevance of the work.
3. Description of Work (Procedure)
A brief description of the actual work performed to explain
where and how the data in the report was
obtained. Do not copy the manual word for word; you should
remember what you did in lab.
4. Results and Discussion
May include answers to specific questions and outcome of lab in
this section. If required, should include
the data (preferably in a tabulated form) and graphs
Tables
always referred to in the
results and discussion section.
Figures
axis (abscissa) while the vertical axis is
only used for the dependent variables.

a convenient scale on each axis in
such a way that the plot will fill roughly half the page.
more than one plot is included in the
figure.
bottom.
in Excel.
Sample calculations
Include a sample calculation for each nontrivial type of
calculation.
Additional info
1. Typewritten, single spaced on 8 ½ x 11 paper.
2. Attach appropriate rubric to front of Memo report.
3. Reference sources only if they are used
The following is an example of a memorandum report.
Hardness and tensile strength of a cartridge brass sample were
measured as a function of percent cold
work (0-60%CW). Both properties increased with the increased
percentage of cold work. Recovery,
recrystallization, and grain growth characteristics of a 50%CW

brass was also investigated by measuring
Rockwell Hardness (B Scale) of specimens annealed for 1/2
hour in the temperature range of 200- 700°C.
A typical curve with the three distinct regions was obtained.
The grain size was also determined for the
three highest annealing temperatures and a dramatic increase in
the average grain size with temperature
was observed.
Procedure
The initial hardness and tensile strength of 70/30 cartridge brass
were measured using the Rockwell
hardness tester (B scale) and the Instron machine, respectively.
The thickness of the samples was
successively reduced by rolling up to 60%, while hardness and
ultimate tensile strength (UTS)
measurements were determined at the different stages of cold
work. A 50% CW brass strip was then cut
into eight pieces, each was annealed at 200, 250, 300, 350, 400,
500, 600, and 700 °C for 1/2 hr, followed
by water quench. The hardness of each sample was finally
measured using the Rockwell tester.
Samples for the metallographic observation were polished,
etched and observed in a light optical
microscope at magnification x 100. The ASTM grain size
number, n was determined by comparing the
microstructure with a standard ASTM grid, and consequently
the average grain size was computed.
Results and Discussion
The data on hardness and tensile strength as a function of the
degree of cold work are shown in Table 1.
Figures 1 and 2 show the reduction in hardness in terms of
inches and percentage of original thickness.
The hardness has increased from about 15 to 78 on the Rockwell

B scale as a result of 60% CW. The
tensile strength has also varied in a similar trend with the
increased amount of cold work. The scatter of
the data is very small since both properties were taken as the
average of several readings under the same
test conditions. Furthermore, the data obtained was in rather
good agreement with those published in the
literature. Process annealing of the cold worked samples below
250 °C reduced the hardness very slightly.
An abrupt decrease in hardness was observed in the temperature
range 250-500°C. Above 500°C the
hardness continued to decrease at a very small rate until 700oC
has been reached. The three stages of the
annealing process, namely recovery, recrystallization, and grain
growth, have been established
accordingly. This is shown clearly by plotting the data in Table
2. The hardness values at high
temperatures exhibited greater scatter as is expected when
approaching the lower limit of the B scale on
the hardness tester. Minor scatter in the values is observed as a
result of the statistical errors involved in
such measurements. However, the results in general are in good
agreement with the literature.
Table 1: Rockwell Hardness and Tensile Strength of Cartridge
Brass at Different Percentages of
Cold Work
% CW RB* UTSx10
-7 (N/m2)
0
10
20
30

40
50
60
15
50
65
70
73
75
78
34
38
43
48
54
60
65
* Average of four hardness readings on Rockwell B scale.
Table 2: Hardness and Grain Size of 50% CW Cartridge Brass
as a Function of Annealing
Temperature.
Temperature oC <RB>* Grain size (mm)
25
200
250
300

350
400
500
600
700
75
73
71
52
40
25
17
18
10
0.010
0.041
0.060
0.154
* Average of four hardness readings.
C old Working
0.0
20.0
40.0
60.0
80.0

100.0
0.1000 0.1200 0.1400 0.1600 0.1800 0.2000 0.2200 0.2400
0.2600
Thickness, inches
H
a
rd
n
e
s
s
,
R
B
brass
Figure 1: Cold Worked Brass showing reduction in thickness
versus RB hardness.
C old Working
0.0
10.0
20.0
30.0
40.0
50.0

60.0
70.0
80.0
90.0
100.0
0 0.1 0.2 0.3 0.4 0.5 0.6
P ercentage reduction in thickness
H
a
rd
n
e
s
s
,
R
B
Figure 2: Cold worked brass percent reduction in thickness
versus RB hardness.
References
1. L. H. Van V lack, "Elements of Materials Science and
Engineering," Addison Wesley, Inc., 1975.
2. R. A. and P. K. Trojan, "Engineering Materials and Their
Applications," Houghton Mifflin Co., 1975.
3. A. G. Guy, “Introduction to Materials Science,” McGraw
Hill Book Co., 1972.
4. Metals Handbook, ASM, edited by T. Lyman, 1948.

EXPERIMENT 7
HARDENABILITY OF STEELS
Purpose
This experiment is aimed at understanding the effect of cooling
rate on the hardness of two
steels. The experiment also shows why adding alloying
elements other than carbon enables a
part to be heat-treated more uniformly and to a greater depth.
Background
The background for Experiment #6 describes why the rate of
cooling affects hardness but it
does not explain why some parts that are heat-treated do not
reach a high hardness. This
problem, which is very real, is not well understood by the
average engineer.
In a practical sense it is not possible to heat-treat all parts to the
same degree. The difference
is due to the thickness or volume effect. Basically, when a part
is quenched in water or some
other fluid, the heat must be conducted out through the surface.
This leads to a temperature
gradient dt/dx between the surface and the center of the part
being heat-treated. The
temperature gradient varies with time.
The temperature gradient is less steep between the center and
the edge at later times.
Therefore, the temperature of the center lags in time behind the
temperature of the surface. If
we were to plot a time profile of the center and the edge
temperatures as shown in Figure 7-1,

the time to reach a given temperature T2 is definitely longer in
the center than at the edge.
This means that cooling rate varies as a function of depth. The
greater the depth the slower
the cooling rate.
The situation with respect to the cooling rate can lead to a
different hardness in the center
than at the edge. The edge could transform to martensite and
the center to pearlite or bainite.
In selecting a steel, the ability to cool the center depends upon
the thickness of the part. The
thicker the part, the slower the cooling rate at the center. For a
given thickness, one must
select a steel that can be hardened in the center if that is
desired. The cooling rate in this case
is fixed. The center part of steel can be hardened by shifting the
time-temperature-
transformation diagram through alloying. Figure 7-2 shows that
alloying elements added to
plain carbon steel can shift the nose of the TTT curve to longer
times and raise the Ms
temperature. This means a slower cooling rate can be used to
reach the martensitic state. A
slower cooling rate means a thicker part can be heat-treated.

To obtain standardized data on the hardness of steels as
functions of cooling rates, the Jominy
End Quench test was developed. In the test, water is sprayed on
one end of a bar of steel
while it is hot. This leads to a one dimensional heat transfer
cooling. Except near the surface
of the bar the temperature is controlled by heat flow along the
length of the bar (like
thickness in the part).
Moving axially away from the quenched end of the bar, the
temperature and the rate of
change of temperature are changing. The temperature is higher
and the cooling rate is lower.
If surface hardness is measured as a function of distance from
the end, a hardness profile can
be obtained which applies to any part made from the same steel,
as shown in Figure 7-3.
Procedure
You will be given two steels: (type 1045) and a low-alloy steel
(type 4143). Before heating
the specimens, practice mounting the specimens in the rack and
adjusting the water flow to
spray the end of the specimens.
Stamp each specimen for identification and measure the
hardness on the Rockwell A scale.
Check to make sure the fork is secure and put the specimen in
the furnace at 1600 + 25oF
(870 + 45oC) for 45 minutes. While you are waiting for the
specimens, examine the
microstructure of the alloy steel and carbon steel specimens
provided by your instructor. At

the end of the austenitizing treatment above remove one
specimen and carefully, but rapidly,
place the specimen in the holder with the water turned on.
Methods of Test
The standard method for the Jominy test is ASTM - A255. The
test consists of austenitizing
at 50°F (90°C) above the solvus line on the Fe-C phase diagram
that separates γ from γ + α.
The specimen is then removed from the furnace and is placed in
the cooling tower. The time
spent transferring the specimen from the furnace to the fixture
should not be more than 5 sec.
The fixture is constructed so that the specimen is held 1/2 inch
above the water opening with
the column of water directed only at the bottom of the bar. The
water opening is 1/2 inch in
diameter and the flow adjusted to cause the column to rise 2-1/2
inches without the specimen
in place. The test piece is held in the fixture for 10 minutes
before quenching in cold water.
After cooling, one flat surface 0.025 inches deep is ground
along the length of the bar.
Rockwell A hardness measurements are taken every 1/16 inch
for the first inch and every
1/8 for the next inch and 1/4 for the next 2 inches. After
hardness measurements are
completed, the results should be compared to the New Metals
Handbook (Vol. 1)

Glossary of Terms
Understanding the following terms will aid in understanding
this experiment.
Hardenability. The ease with which a steel can be quenched to
form martensite. Steels with high
hardenability form martensite even on slow cooling.
Hardenability curves. Graphs showing the effect of cooling rate
on the hardness of a steel.
Jominy test. The test used to evaluate hardenability. An
austenitized steel bar is quenched at one
end only, thus producing a range of cooling rates along the bar.
Quenching. Rapidly cooling a material to some lower
temperature by immersion in a liquid bath or
gaseous stream. For example quenching steel in a pail of water.
Temperature gradient. A difference in temperature across some
distance, for example between one
end of the Jominy bar and the other.
Write Up
Prepare a memo report, in conjunction with Experiment #6
(Heat treatment of steels). Plot
the hardness as a function of distance from the quenched end
with plots for both samples
on the same graph. Discuss the effects of alloying on
hardenability. Discuss the shift in the
TTT curve due to alloying.

References
ASM Vol. 1, Properties of Iron and Steel, 1977.
D. Callister Jr, Fundamentals of Materials Science and
Engineering, J. Wiley & Sons, NY, 2nd Ed.
2005, Chapter 5
Flinn and Trojan, Engineering Materials and Their Applications,
Chapter 6

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