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Materials (18MTY)
Winter term 2018/2019
lectures: MSc. Jaroslav Valach, Ph.D.
practicals: MSc. Petr Koudelka
http://mech.fd.cvut.cz/education/bachelor/18mty-en/download/18MTY_sylabus_2018_
en.pdf
1 Main topics
• Mechanical properties of materials
• Experimental testing of mechanical properties of materials
• The main classes of materials
• Defectoscopy
• Degradation of materials
2 Main goals of the course
Student will obtain a general overview of technically important materials (metals, polymers,and composites). The basic level materials science course builds a consistent explanation ofmaterials from the level of atomic level to practical procedures during technological processesand material production. He/she will also understand decisive mechanical properties of mate-rials for engineering and technology on the basis of hands-on practicing of the most importantmechanical tests like tensile test or hardness test.
3 Literature
W.D. Callister, Jr.: Materials science and engineering: an introduction. John Wiley & Sons 2000
4 Topics of lectures
• Mechanical properties of materials, goal of materials science.
• Structure of materials.
• Crystal structure, lattice defects.
• Solid solutions, thermodynamics and binary diagrams.
• Steel and cast iron, quenching, tempering, annealing.
• Fe-C diagram, special steels and alloys. Non-ferrous metals.
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• Polymers, structure, processing, mechanical properties.
• Glass and ceramic, major use, explanation for strength and fragility.
• Composites - properties, advantages, synergies, fibers and matrix.
• Degradation of materials, nondestructive testing.
5 Schedule of practicals
1. Conditions for course credit assignment, safety rules in the Laboratory of experimentalmechanics, introduction to mechanical testing of materials, uni-axial tensile test.
2–4. Mechanical testing of materials – uni-axial test, hardness test, Charpy impact test.
6 Organization of practicals in Laboratory of experimental me-chanics
• The group of students will be divided into three measurement sub-groups of at least twoand maximum five students.
• Each measurement sub-group will study theory of every type of laboratory measurementwith emphasis put on directly measured quantities (including units), derived quantitiesas defined in test assignment (including units), and mathematical relations for evaluationof the test.
• In the beginning of measurement practicals, the knowledge of students will be checkedby the teacher and the group will then begin with preparations for the measurementaccording to manual in the test assignment.
• The students will without exception obey instructions given by the teacher to follow thesafety rules and to avoid damage to the testing machines.
• Steps, where the explicit approval of the teacher is required, are in the testassignment highlighted in bold font.
• After the measurement, the teacher will sign any values measured by the students thatwill be used during evaluation of the test.
6.1 Laboratory protocol
Example of laboratory protocol can be found at:http://mech.fd.cvut.cz/education/bachelor/18mty-en/download/18MTY_report_template.
pdf/view
6.2 Schedule of laboratory measurements
The group of students will be divided into three measurement sub-groups, where the number ofthe sub-group will serve as a key to order of test performed in the Laboratory of experimentalmechanics. Schedule is shown in Tab. 1.
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Measurement sub-group no. 20 November 2018 4 December 2018 18 December 2018
1 tensile test hardness test impact test2 impact test tensile test hardness test3 hardness test impact test tensile test
Table 1: Schedule of measurements in the Laboratory of experimental mechanics
7 Conditions for course credit assignment
1. Delivery of all laboratory protocols and individual exercises in final form approved by theteacher.
• Assignments of laboratory measurements and individual exercises can be found inAppendix.
2. All conditions have to be met at the latest on 8 January 2019.
8 Exam
8.1 Organization of exam
1. Valid course credit assignment is required for registration to exam.
2. The exam is composed of written and oral part. Satisfying the conditions for pass in thewritten part is mandatory prior to the oral part.
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A Assignments of laboratory measurements and individual ex-ercises
A.1 Uni-axial test
Perform quasi-static uni-axial test and evaluated the measured data. Determine ultimatestrength, yield strength, ductility, and Young’s modulus. Use long gauge length.
A.1.1 Measurement system and tools
• Testing system Instron 3382 (control software Series IX)
• Vernier caliper
(a) Electro-mechanical testing system (b) Specimen
Figure 1: Tensile test
A.1.2 Measurement procedure
• Measure cross-section of the specimen.
• Mark the gauge length on the specimen.
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• Fix the sample in the grips.
• Ask the teacher to start the test.
• Save the acquired data.
• Measure length of the sample after the breakage.
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A.2 Hardness test
Perform Vickers hardness test, evaluate Vickers hardness, and correctly write the result.Perform 10 measurements using the provided sample, calculate the average value and thestandard deviation.
A.2.1 Measurement procedure
• Turn on the illumination of the testing machine.
• Put the specimen on the table of the hardness testing machine.
• By turning the wheel, set height of the table so that sharp image can be seen on theground glass.
• Based on instruction of the teacher, press lever 1.
• After the prescribed duration of the test, press lever 2.
• Measure diagonals of the imprint using image on the ground glass.
Figure 2: Vickers hardness testing machine
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(a) Ground glass withMatnice s movablegauges
(b) Detail of the imprint (cap-tured using scanning electronmicroscope)
Figure 3: Vickers hardness test
A.3 Charpy impact test
Perform the Charpy impact test. Use a room temperature sample and a frozen sample.Evaluate impact energy for both specimens and the resulting toughness. Correctly write theresults.
A.3.1 Measurement device and tools
• Impact test machine
• Vernier caliper
• Freezer spray
A.3.2 Measurement procedure
• Measure dimensions of the specimen.
• Place the sample on supports of the testing machines.
• Reset the gauge.
• Based on instruction of the teacher, put the hammer into initial position andsecure the ratchet.
• Ask the teacher to release the ratchet.
• Write down the measured energy of the hammer after test.
• Perform calibration test without the specimen to evaluate mechanical losses. The ratchetwill be released by the teacher!
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(a) rest position (b) before start of the test
Figure 4: Impact test machine
(a) Intact specimen (b) Specimen after test
Figure 5: Specimen for Charpy impact test
A.4 Individual exercise 1
Evaluate theoretical density of material given in the table 2. Obtain the required data froma trusted source and provide citation. Properties of the crystal structures are temperaturedependent. Provide information on temperature, for which the theoretical density is calculated.
Month of birth chem. element Month of birth chem. element Month of birth chem. element
January Ni May Al September VFebruary Au June Cr October Mo
March Ir July Pb November AgApril Pd August W December Li
Table 2: Chemical elements for exercise 1
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A.5 Individual exercise 2
Describe phases present in the alloy as defined in figure 6 with chemical composition givenby equation 1 and temperature given by equation 2. Determine relative ratio of these phasesin the solid solution at the given chemical composition and temperature (use the lever rule).Determine the average density of the solid solution with the given chemical composition atroom temperature. Consider homogeneous distribution of phases in the whole volume. Obtaindensity of chemical elements Sn and Pb in a trusted source and provide citation.
T [ C]
100%Pb100%Sn
0 20 30 40 50 60 70 80 90 100
0
60
120
180
240
300
hm. %Pb
ββ
α+β
α
L
L+ α L+
10
327 C
232 C
183 C
2.5 61.9 80.8
Figure 6: Eutectic equilibrium phase diagram
X = 10 +day of birth ∈< 1; 31 >
0.45[hm.%Pb] (1)
T = 80 +month of birth ∈< 1; 12 >
0.12[oC] (2)
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