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2006-36: IMPROVING STUDENT LEARNING OF MATERIALS FUNDAMENTALS
Robert LeMaster, University of Tennessee-MartinRobert LeMaster is an Associate Professor at the University of Tennesee at Martin. He has over20 years of research, development, and management experience on NASA and Air Force projects.Dr. LeMaster received a B.S. degree in Mechanical Engineering from the University of Akron in1976, an M.S. degree in Engineering Mechanics from the Ohio State University in 1978, and aPh.D. degree from the University of Tennessee in 1983.
Ray Witmer, University of Tennessee-MartinAssistant Professor University of Tennessee at Martin, Registered Professional Engineer
© American Society for Engineering Education, 2006
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Improving Student Learning of Materials Fundamentals
Introduction
All engineering students at the University of Tennessee at Martin (UT Martin) are required to
take an introductory course in materials science and engineering. This is a common requirement
for most engineering programs. At UT Martin this introductory course consists of two lecture
hours and one three-hour lab per week. Additional exposure to materials concepts and
applications are obtained through courses such as Strength of Materials, and depending on the
area of concentration courses in Reinforced Concrete, Soils, Manufacturing Processes,
Electronics, and Machine Design. An examination of student performance on the Materials and
Structure of Matter section of the Fundamentals of Engineering (FE) examination showed that
UT Martin students consistently scored below the national average and that the trend was
constant to slightly negative.
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Figure 1. Comparison of UT Martin test
results with national average
Figure 1 shows data that compares UT Martin
test results to the national average. UT Martin
students take the General Engineering Exam
which includes a materials section in both the
A.M. and P.M. test sessions. Results are shown
for both test sessions. The results shown in the
figure are based on a four-point running average
that is used to dampen the oscillations
associated with individual test sessions.
Removing the oscillations enables trends to be
more easily seen. As seen in the figure, UT
Martin scores were consistently 5-10% below
the national average with slight negative trend.
UT Martin’s goal is to have students
consistently score at or above the national
average on this exam. This goal was not being
met in this subject area.
UT Martin uses data from the FE to assess whether or not some program outcomes are being
met. Core Curriculum Committees are responsible for reviewing the assessment data for groups
of courses and determining whether or not changes in course content is needed. The Core
Curriculum Committee responsible for the materials course determined that the textbook,
prerequisites, and content covered in the course was similar to those at other universities.
Therefore, reasons other than content had to exist that would explain the lower than expected
performance. During the course of this review a number of potential contributing factors were
identified. First, not all students had completed the materials course at the time of the
examination. Depending on the area of concentration, materials may not be a prerequisite for
another course and in some cases students put off taking the course until their last semester of
enrollment. It was decided that this problem was best addressed through advising in which
faculty made sure that students took the junior level course in their junior year instead of
deferring it until their last semester. Second, it was determined that only the laboratory portion
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of the course contained only a few experiments and it was decided that the laboratory portion of
the course needed to be strengthened. The strengthening of the laboratory portion of the course
is the emphasis of this paper.
Experiment Enhancement
A review of experiments used at other universities in conjunction with a first course in materials
was performed. As part of this review, lab report requirements were also examined. Information
was obtained from: 1) a visit to another campus (University of Tennessee – Knoxville) to
observe laboratory sessions and equipments, 2) discussions with colleagues from other
universities, and 3) experiments published in both the literature and on the web. As a result of
this review a set of ten experiments were selected for implementation at UT Martin. These
experiments were selected based on their correlation with lecture content, their ability to
demonstrate fundamental concepts, and the practicality of implementing them from the
standpoint of laboratory time and equipment. In most cases the experiments were modified to
better fit within the equipment and lab time constraints at UT Martin. These experiments are
listed in Table 1 along with the major topics covered by the experiment. The following sections
provide a brief summary of each experiment.
Table 1. List of Experiments and Major Concepts Covered
Lab Title Concepts Covered
1. Crystals and Crystallography Crystal structures and interstitial sites
2. Tensile Properties of Metals Stress-strain curves and fracture
3. Ductile to Brittle Transition Fracture energy versus temperature
4. Cold Work and Recrystallization Annealing and recrystallization
5. Phase Diagrams Cooling curves and phase transformations
6. Hardenability of Steels Jominy bar end quench
7. Quench and Temper Heat Treatment Tempering curves
8. Galvanic Corrosion Electrical potentials and corrosion
9. Fracture of Glass Brittle fracture and Weibull Statistics
10. Hyperelastic Response of Elastomers Nonlinear response and Mooney-Rivlin equations
Experiment 1: Crystals and Crystallography
The objective of this laboratory is to learn the basic types of crystal structures and to develop a
sense for the relationships between them. The exercises included in this laboratory familiarize
the student with the face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal
close-packed (HCP) crystal structures. The structures are studied to determine the important
crystallographic parameters relating to crystal symmetry, density of atomic packing, and the
location and size of open spaces within the crystal.
This type of laboratory is fairly common and a variety of methods are used by universities to
construct the unit cells. For example, the University of Delaware uses Solid-State Model Kits
that are designed to allow models of many types of crystal structures to quickly be assembled 1.
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In the past UT Martin required students to construct
the three crystal structures from ping-pong balls and
hot glue. Currently they are required to build 3-
dimensional models of the crystal structures using the
I-DEAS CAD software (Figure 2). Using I-DEAS
requires that the students calculate the lattice size
parameters and the location of the atoms. They also
learn to calculate the size of interstitial spaces and the
size of atoms that will fit within them. These
calculations are important and having students make
them as part of the lab helps to ensure that they know
how to do them. Lattice size parameters and atom
location calculations were not required when
constructing the unit cells from ping-pong balls. The
instructors have found that having ping-pong models
of the crystal structures available during the lab
sessions helps explain and answer questions raised by students.
Figure 2. HCP crystal structure
developed using I-DEAS in
Crystals and Crystallography Lab
Experiment 2: Tensile Properties of Metals
The objective of this experiment is to learn how metals respond to axial loads, understand the
terminology and parameters used to describe this response, gain familiarity with ASTM
standards, and gain experience using tension and hardness test equipment. Tensile tests,
particularly of metallic materials, are fundamental tests that are performed at many universities.
At UT Martin five different materials are used in this lab – AISI 1018, 4140, and 8620 cold
drawn steel, 6061-T6 aluminum, 360 brass, and ASTM A36 hot rolled steel. The 1018, 4140,
and 8620 steels are used to show the effect of alloying on the tensile properties of steel – all
demonstrate a smooth transition from the elastic to work hardening portions of the stress-strain
curves. Aluminum and brass are used to provide a comparison of the strength and toughness of
different materials. They also demonstrate a smooth transition form the elastic to work
hardening portions of the stress-strain curves. The hot rolled A36 specimen is used to
demonstrate high and low yield point phenomena exhibited by some materials. Hardness
measurements are made on all samples prior to the performing the tensile tests. The pre-test
hardness values are compared to post-test hardness data taken from the fracture zone to show the
increase in hardness associated with work hardening.
Experiment 3: Ductile to Brittle Transition
The objective of this experiment is to learn how the ductility of metals is affected by
temperature, how this dependency can be determined using Charpy V-notch tests, learn the
terminology and parameters used in Charpy V-notch tests, gain familiarity with ASTM
standards, and gain experience using an impact test machine. Charpy impact testing is also
commonly used in conjunction with first courses in materials science 2,3,4
. At UT Martin,
fracture energy data is measured for three materials – Grade 40 gray cast iron, 1018 low carbon
steel, and 6061-T6 aluminum – at six temperatures (Table 1). The six temperatures do not
provide sufficient data to locate the ductile-brittle transition temperature, but do allow the
presence of an upper and lower fracture energy plateau to be identified if one exists. Typically, Page 11.739.4
the cast iron is brittle at all temperatures, the low carbon steel demonstrates an upper and lower
fracture energy plateau, and the aluminum does not become brittle at the lower temperatures.
Table 1: Temperatures used in Charpy V-notch Experiements
Temperature (oF) Method used to Obtain Temperatures
500 Furnace
212 Boiling water
70 Room temperature
32 Ice water bath
-109 Ethylene glycol and dry ice bath
-321 Liquid nitrogen bath
Experiment 4: Cold Work and Recrystallization
The objective of this experiment is to determine the relationship between percent cold work,
%CW, and recrystallization temperature, demonstrate the effects of cold work and
recrystallization on the hardness of the alloy, learn the terminology and parameters associated
with cold work and recrystallization, gain experience using ASTM standards, and gain
experience using hardness testing and furnace equipment. In this experiment ½ inch by 1/8 inch
by 4 inch samples of 360 cartridge brass are reduced in thickness by rolling. Typically 10%,
20%, 30%, 40% and 50% thickness reductions are used. After rolling, the samples are cut into
half inch lengths. The various samples are placed in annealing furnaces having temperatures of
275 oC to 475
oC in increments of 50
oC. After being annealed for one hour, the hardness of each
sample is plotted as a function of annealing temperature. Experiments similar to this one that are
used at other universities can be found in references 4 and 6.
Experiment 5: Phase Diagrams
The objective of this experiment is to learn how phase diagrams are constructed from a set of
cooling curves obtained for various alloy compositions, learn the terminology associated with
phase diagrams, and gain experience with measuring and mixing alloying components. Several
similar experiments are reported in the literature 1,4,5
. This particular experiment is modeled after
one developed by the Material Science Department at the University of Tennessee – Knoxville.
Six small furnaces (Figure 3) are used to melt alloys of Pb and Sn – other alloys having a binary
eutectic phase diagram could be used. Cooling curves are then obtained and simultaneously
displayed using the LABVIEW graphical user interface (GUI) shown in Figure 4. As the cooling
curves are developing the instructor is able to discuss them in real time using a projected image
of the GUI. The raw data is saved in a file which is used by each student to determine the
liquidus, solidus, and transformation times.
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Figure 3. Jeweler’s melting furnace used in phase-diagram experiment.
Figure 4 – LABVIEW GUI used during phase diagram experiment.
Experiment 6: Hardenability of Steels
The objective of this experiment is to learn how cooling rate effects the hardness of quenched
steels, demonstrate the difference in the ability of alloys to harden (e.g. hardenability of steels),
learn how the hardenability of steels is measured using the Jominy Test, gain familiarity with
ASTM standards, and learn the terminology associated with the Jominy hardenability test
(ASTM A225). This experiment is performed in accordance with the ASTM A225 standard
using an end-quench apparatus designed and fabricated at UT Martin (Figure 5a). Figure 5b
shows students removing a specimen from a furnace and loading it in the end-quench apparatus.
Note the safety gear being worn by the students. Three alloys are used in this experiment – AISI
1020, 4140, and 4340 – to demonstrate the effect of carbon and alloy content on hardenability.
The 1020 alloy does not harden or demonstrate good hardenability due to the low carbon content.
Both the 4140 and 4340 develop greater surface hardness than the 1020 alloy due to the higher
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carbon content. The 4340 alloy which has a higher chrome content demonstrates a much better
through thickness hardenability than does the 4140 alloy. As with the other experiments, this
type of experiment is also performed at other universities 1,4
.
Figure 5 a) Jominy specimen during quench, and b) students loading specimen in quench
apparatus.
Experiment 7: Quench and Temper Heat Treatment
The objective of this experiment is to learn how the properties of steels can be changed by heat
treatment processes involving the transformation of austenite to martensite, demonstrate the
effects of time and temperature on the properties of tempered martensite, and learn the
terminology associated with the heat treatment of steels. The six furnaces used during the phase
diagram experiment are used to temper small samples of AISI 4140 that were previously
austenized and quenched. The samples are tempered for one hour and a different tempering
temperature is obtained from each furnace. Using six furnaces simultaneously enables the data
to be obtained in one lab session.
Experiment 8: Galvanic Corrosion
The objectives for this experiment are to gain familiarity with the terminology used to describe
and measure corrosion, to learn about the electromechanical behavior of corrosion, to discover
which metal in a group is the most noble and which corrodes the most, and to study the concept
of sacrificial anodes and way to prevent corrosion by using them. This lab is an adaptation of
corrosion experiment conducted at the University of New Brunswick and described in Reference
7. In this experiment the electrical potential between dissimilar metals in an electrolyte is
measured for several materials, which allow students to gain a hands-on understanding of the
galvanic series.
Experiment 9: Fracture of Glass
The objectives of this experiment are to: 1) characterize the load-deflection curve for an
elastic/brittle solid, 2) calculate the fracture stress and quantify the variability of this property, 3)
observe delayed fracture when this brittle solid is loaded near the instantaneous breaking load,
and 4) gain familiarity with the terminology and testing methods associated with brittle fracture.
This experiment is an adaptation of that found in Reference 1. In this experiment precision dial
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indicators are used to measure the mid-span deflection of
glass specimens loaded in three-point bending, Figure 6.
The glass specimens are standard microscope glass slides
(1in x 3in x 0.4in) used in biological labs. The load-
deflection data is used to determine Young’s modulus for
each sample. Statistical properties of Young’s modulus
are determined assuming a normal distribution. The
fracture data is used to determine the parameters for a
two-parameter Weibull distribution.
Experiment 10: Hyperelastic Response of Elastomers
The objectives of this experiment are to determine how
elastomers elongate under load and to experimentally
determine constitutive equation constants for the Neo-
Hookian, Mooney-Rivlin and Mooney-Rivlin (augmented
with an exponential term) equations. This experiment is
modeled after experiments found in References 4 but has
been expanded to include more hyperelastic type
constitutive equations (i.e. Mooney-Rivlin). In this
experiment digital dial calipers are used to measure the
distance between gage marks on a rubber band as it is
stretched. The rubber bands are loaded with small
weights and both the load and unload response is examined. Journal exercises require the
determination of the material constants for the various constitutive equations. Excellent data is
obtained with a little care. Figure 7 shows comparisons of the three constitutive equations to the
test data.
Figure 6. Small three-point load
frame developed by R. Witmer for
Fracture of Glass experiment.
Constitutive Equation Comparison
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Mooney-Rivlin
Mooney-Rivlin
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Neo-Hookian
Figure 7. Comparison of Constitutive Equations and Experimental
Data for Hyperelastic Response of Elastomers Experiment
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Lab Reports
A variety of lab report requirements were encountered during the review of experiments and
practices used at other universities. These ranged from formal lab reports written by teams to
laboratory journals that were hand written by each student. In some cases the lab
reports/journals reported and interpreted data only for the experiment under consideration, while
others required that students provide answers to additional questions. The approach adopted at
UT Martin was to have students prepare individually hand written lab journals. The adoption of
this approach was based on the time required by students, faculty grading time, and the assurance
that all students would do all of the work. The journals contain information about the
experiment being conducted, data, data interpretation and analysis, and the answers to a series of
questions that require the students do research outside of the lab setting. The additional
questions are similar to homework problems, and including the questions with the lab journals
ensures that all students do the homework and obtain feedback on it. There are generally several
questions associated with each experiment and students will have to spend several hours
answering them. Example questions are listed in Table 2.
Table 2: Example of questions answered in lab journal
Lab Question
1 Calculate the theoretical density of Ni at room temperature. Perform research to
determine the atomic radius and crystal structure. Compare your value to the
reported in the literature. Cite your reference.
2 Determine the ASTM E8 specified load rate. Determine the chemical
composition of each specimen.
3 Review ASTM Standard E24 and provide a dimensioned sketch of the Charpy
specimen.
4 Review ASTM E18 and ASTM E140 to convert the Rockwell B hardness data to
Brinnell hardness. Determine the chemical composition for 260 cartridge brass.
Cite your reference.
5 Show the temperatures associated with the start and end of solidification on a
published Pb-Sn phase diagram. Discuss how these temperatures compare to the
liquidus and solidus lines on the phase diagram. Citer your references.
6 Review ASTM A255 and sketch the experimental setup for the Jominy Test.
Make a sketch of a time-temperature transformation curve for a “typical”
hypoeutectoid plane carbon steel and sketch the cooling path for the
transformation of austenite to martensite by a water quench. Cite your
references.
7 Create a graph that shows tensile strength versus tempering temperature. Cite
your reference for the conversion of RHB to tensile strength.
8 Construct a galvanic series for the five metals listing the most cathodic to the
most anodic. Compare these with a published list of ½ cell potentials. Cite your
references. Discuss any similarities or differences.
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Online Tools and Resources
The Blackboard web-based course management software is used in this course. All lectures are
presented using Power Point and the lecture notes are made available to students online. Web
access to common lab data that must be used by students to prepare lab journals is also facilitated
by the Blackboard. This course also uses the online testing capability of Blackboard. An
introductory course in materials science and engineering does not involve lengthy calculations
with lots of algebraic manipulation. Calculations can be done quickly and many questions can
be asked during an examination. This requires students to study all of the material associated
with a test because there is a good probability that there will be question on all areas. Tests used
in this course typically contain approximately 40 questions. This many questions allow the tests
to cover a lot of breath while still enabling students to have enough time to finish the exam. It
also allows adoption of a no partial credit rule since each question is only worth a few points.
Students are not given a copy of the exam after it has been taken. They are allowed to come by
the instructor’s office and see which ones they missed, but they do not have a copy of the test
that can be passed along to future students.
Data Analysis
The primary source of data used to determine if the
students were learning materials better was student
performance on the Materials and Structure of
Matter sections of the NCEES Fundamentals of
Engineering Exam (FE). The number of materials
related questions contained on either the A.M. or
P.M. section is relatively small – on the order of
eight. Thus the FE exam data can provide only
limited insight into the depth and breadth to which a
student understands a subject area.
Table 3: Ratio of UTM Correct /
National Correct
Test Date A.M P.M.
Before Course Changes
April 2001 1.07 0.89
October 2001 1.02 1.08
April 2002 0.84 1.02
October 2002 1.04 0.70
April 2003 0.86 0.85
Average 0.96 0.91
After Course Changes
October 2003 1.02 0.97
April 2004 1.00 0.78
October 2004 1.11 1.00
April 2005 0.78 0.98
October 2005 1.07 0.91
Average 1.00 0.93
The metric used in this study is the ratio of the
average number of questions answered correctly by
UT Martin students divided by the average number
of questions answered correctly by all students (i.e.
national average). Table 3 shows this ratio for April
and October test offerings starting in April 2001
through October 2005. The table also shows the
average for both the A.M. and P.M. test sessions
before and after the course changes.
The percent correct ratio prior to the laboratory changes was 0.96 and 0.91 for the A.M. and P.M.
sessions respectively. The percent correct ratio following the laboratory changes was 1.00 and 0.93
respectively. This represents a 4.0% improvement in the A.M. sessions and a 2.2% improvement in
the P.M. sessions.
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Figures 8 through 11 contain plots of the data contained in Table 3. Each plot shows fluctuating
results along with a linear regression curve fit. The slopes of the linear regression curves can be
used to identify trends in the data. The data for the A.M. and P.M. sessions prior to the laboratory
changes (Figures 8 and 9) show negative trends (i.e. performance is getting worse). The data for the
A.M. and P.M. sessions after the course changes (Figures 10 and 11) show a positive trend (i.e.
performance is getting better) for the A.M. session, while the P.M. session continues to show a slight
negative trend. The trend line slope shown in Figure 11 is -0.6x10-4 compared to -2x10-4 for Figure
9. Therefore, although the trend for the P.M. sessions is still slightly negative, it has been made less
negative by 70%.
y = -0.0002x + 8.9059
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Figure 8. Ratio for A.M. Test Sessions Prior to
Laboratory Changes
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Jun-03 Jan-04 Aug-04 Feb-05 Sep-05 Mar-06
Figure 11. Ratio for P.M. Test Sessions After
Laboratory Changes
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Figure 10. Ratio for A.M. Test Sessions After
Laboratory Changes
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1.20
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Figure 9. Ratio for P.M. Test Sessions After
Laboratory Changes
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Conclusions
This paper describes efforts taken at the University of Tennessee at Martin to improve student
understanding in the area of materials science and engineering. The monitoring of test results
from the Fundamentals of Engineering Exam in a particular subject area was used to determine
the need for improvement and to assess whether efforts are leading to improvement.
Efforts to improve student understanding and retention focused on strengthening the laboratory
portion of an introductory course in materials science and engineering. Strengthening the
laboratory experience required adding experiments and in some cases additional lab equipment.
It also required having students individually prepare handwritten lab journals that require the
students to not only record and discuss data but to research ASTM standards, course material,
and texts to answer questions relating to the material. The laboratory portion of this course is
now much more intensive than in previous offerings.
Data from the Fundamentals of Engineering Exam suggest that student understanding of
materials science and engineering has improved as a result of the laboratory improvements.
Average test scores for the A.M. session improved by 4% while the P.M. session scores
improved by 2%. The negative trend in test scores for the A.M. test sessions prior to the changes
was made positive, while the negative trend in test scores for the P.M. test sessions was made
less negative by 70%.
Bibliography
1. MASC 302 Materials Science for Engineers – Laboratory Notes for Mechanical Engineers, University of
Delaware, 2000.
2. Bates, S.P., Charpy V-Notch Impact Testing of Hot Rolled 1020 Steel to Explore Temperature ~ Impact
Strength Relationships, 1990 National Educators Workshop: Standard Experiments in Material Science,
Gaithersburg, Maryland, 1990.
3. 3445 Course Hardness Notes, MECE 3445—Materials Science Laboratory, University of Houston, 2002,
http://www.egr.uh.edu/me/ceramics, observed 1/12/2006.
4. MSE 201 Laboratory Notes, University of Tennessee-Knoxville,
http://www.engr.utk.edu/mse/pages/courses.htm, observed 1/12/2006.
5. Chen, K.C., How We Learned to Love the Phase Diagram with a Ti-Cr Alloy Characterization Lab,
Proceedings of the 2003 American Society for Engineering Education Annual Conference & Exposition, 2002,
American Society for Engineering Education.
6. MIE 302 Handouts, Experiment 3 – Property Modifications of Alloys, University of Massechusetts-Amherst,
http://www.ecs.umass.edu/mie/faculty/nair/mie302/Lab%20Handouts/Lab3.doc, observed 1/12/2006.
7. Galvanic Corrosion of Metals, University of New Brunswick, Department of Chemical Engineering,
http://www.unb.ca/che/Undergrad/lab/2503.htm, observed 1/12/2006.
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