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Eight Sessions
1. Pressurized Water Reactor
2. Quiz, Thermodynamics & HTFF
3. Quiz, Physics & Chemistry
4. Exam #1, Electrical Concepts & Systems
5. Quiz, Materials Science
6. Quiz, Strength of Materials - Statics
7. Quiz, Engineering Disasters
8. Exam #2, Engineering Seminar, Education & Careers
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Materials Science
• Engineers must choose the correct materials
for each purpose and use.
• The properties, strengths and weaknesses,
must be understood.
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Many types of materials
• Iron
• Steel
• Glass
• Plastics
• Rubber
• Semiconductors
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• Physical Properties
• Chemical Properties
• Nuclear Properties
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Types of Materials
• Metals
• Non-metals
• Ceramics
• Polymers
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• Metals – release their electrons
• Non-metals – accept or share electrons,
usually form molecules or anions
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• Ceramics – consists of compounds of
metallic and non-metallic elements
• Polymers - large molecule
(macromolecule) composed of repeating
structural units typically connected by
covalent chemical bonds.
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Types of Materials
• Metals
• Non-metals
• Ceramics
• Polymers
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Bonding in Solids
• Interatomic forces
• Coulombic attractive & repulsive
• Ionic – electron transfer
• Covalent – electron sharing
• Metallic – sharing large numbers of free electrons
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Bonding in Solids
• Ionic – Ceramics
• Covalent – Polymers & Semiconductors
• Metallic - Metals
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Long range order or not
• Crystalline
• Amorphous
– Liquids, glass, plastics
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Metals
• Crystallize during solidification
• Iron
• Steel
• Aluminum
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Steel
• Iron
• Carbon
• Other Alloying Agents
– manganese, chromium, vanadium, and tungsten
Fe 26
56
C 6
12
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• “Carbon and other elements act as a
hardening agent, preventing dislocations in
the iron atom crystal lattice from sliding
past one another.” wikipedia
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Mechanical Properties
• Stress
• Strain
• Strength
– Yield
– Tensile
• Ductility
• Toughness
• Hardness
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Mechanical Properties
• Affected by:
– Alloying agents
– Crystal defects
– Grain size and grain boundaries
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Steel
• Internal Structure
• Crystal Lattice
• Alloy
– Substitution
– Interstitial
• Grains 21
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Crystallize
• During solidification
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Face centered cubic centred
lattice structure of austenite
The figure shows the iron atoms and their relative distances. The (smaller) carbon atoms easily ‘dissolve’ in this lattice. Steel consists
mostly of iron with up to 2 percent carbon by weight. If the carbon content is higher, the material is called cast iron.
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Grains
• The structure in a solidified metal
• Single crystals that are next to each other
• Grain Boundaries – between grains
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Steel grains
microscopic
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Defects in Crystal Lattice
• Point Defects
– Vacancies
– Interstitial atom
• Line Defects
– Edge dislocations
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• “Carbon and other elements act as a
hardening agent, preventing dislocations in
the iron atom crystal lattice from sliding
past one another.” wikipedia
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Diffusion
• Atoms and Vacancies
• Heat Treatments: Annealing
• Change metal properties
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Internal Structure of Commercial Steel
• Many grains
• Each grain: a single crystal
• Each crystal: iron & carbon atoms & the atoms of
alloying agents
• Each crystal has defects in its structure
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Mechanical Properties
• Affected by:
– Alloying agents
– Crystal defects
– Grain size and grain boundaries
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Mechanical Properties
• Stress
• Strain
• Strength
– Yield
– Tensile
• Ductility
• Toughness
• Hardness
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Explain
• Stress
• Strain
• Toughness
• Elastic Deformation
• Plastic Deformation
• Ductile Failure
• Brittle Failure
• Fatigue Failure
• Creep
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Testing Metal Properties
• Tension Test
• Charpy Test - Impact Energy
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Stress – Strain using Tensometer
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Rebar
ASTM A36
Tensile Test Illustration
Young's Modulus Illustration
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Stress vs. Strain curve for structural steel
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Stress vs. Strain curve for structural
steel. Reference numbers are:
1 - Ultimate Strength
2 - Yield Strength(elastic limit)
3 - Rupture
4 - Strain hardening region
5 - Necking region
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Strain
• Deformation
L
L
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Str
ess
Strain
Yield Strength
Ultimate Strength
Fracture
Elastic
Plastic
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Str
ess
Strain
Yield Strength
Ultimate Strength
Fracture
Elastic
Plastic
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Toughness
• Resistance to fracture of a material when stressed.
• Amount of energy per volume that a material can
absorb before rupturing
• Energy required for mechanical failure.
• Area (i.e., by taking the integral) underneath the
stress-strain curve
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Elastic Deformation
• Reversible
• Hooke’s Law: springs
• E is a material constant called Young's
modulus [the spring constant]
E
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Plastic Deformation
• Not reversible
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Ductility
• Extent to which materials can be deformed
plastically without fracture
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Ductile Failure
• Extensive plastic deformation takes place
before fracture
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Brittle Failure
• No apparent plastic deformation takes place
before fracture
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Fatigue Failure
• Progressive and localized structural damage
that occurs when a material is subjected to
cyclic loading.
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Creep
• Tendency to slowly move or deform permanently
under the influence of stresses.
• Long term exposure to stress below the yield
strength.
• Creep always increases with temperature.
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Testing Metal Properties
• Tension Test
• Charpy Test - Impact Energy – Related to
toughness
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Charpy Test Video
Charpy Test Video
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Testing Metal Properties
• Tension Test
• Charpy Test - Impact Energy – Related to
toughness
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Phase Diagrams
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Explain
• Stress
• Strain
• Toughness
• Elastic Deformation
• Plastic Deformation
• Ductile Failure
• Brittle Failure
• Fatigue Failure
• Creep
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Problem with calculations
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Homework for next week
• Required
• Optional
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59
http://230nsc1.phy-
astr.gsu.edu/hbase/pertab/pertab.html
http://ffden-
2.phys.uaf.edu/212_fall2003.web.dir/Mike_Ku
denov%20/Film.htm
http://www.kanescience.com/_chemistry/5Ionic
.htm
http://en.wikipedia.org/wiki/Crystals
http://www.concretestrategies.com/services/ste
el.php
http://www.joyrides.com/kennywood/steel_pha
ntom1.htm
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60
http://www.germes-
online.com/catalog/17/15/601/201778/stainless_steel
_pipe.html
http://en.wikipedia.org/wiki/Stainless_steel
http://en.wikipedia.org/wiki/Steel
http://www.steel.org/AM/AMTemplate.cfm?Section=
Steel_Flowlines1&TEMPLATE=/CM/HTMLDisplay
.cfm&CONTENTID=12908
http://substech.com
http://www.delftoutlook.tudelft.nl/info/indexb71b.ht
ml?hoofdstuk=Article&ArtID=4244
http://www.cartage.org.lb/en/themes/Sciences/Physic
s/SolidStatePhysics/AtomicBonding/CrystalStructure
/Crystalline/Crystalline.htm
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http://en.wikipedia.org/wiki/Crystallite
http://www.matsci.ucdavis.edu/MatSciLT/Othe
r/Other.htm
http://en.wikipedia.org/wiki/Crystallographic_d
efect
http://www.tf.uni-kiel.de/matwis/amat/def_en/
http://en.wikipedia.org/wiki/Ductility
http://www.sciencebuddies.org/science-fair-
projects/project_ideas/MatlSci_StressStrainStre
ngth_h005.shtml
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http://www.youtube.com/watch?v=78gwo9LSP
Ag&feature=related
http://www.youtube.com/watch?v=YdqvGGFIb
fc
http://www.youtube.com/watch?v=5QaqwmZ7
Sic&NR=1 -
http://www.astm.org/Standards/A36.htm -
ASTM A36 / A36M - 08 Standard
Specification for Carbon Structural Steel
http://www.youtube.com/watch?v=mzb4Hpmru
b4&NR=1
http://en.wikipedia.org/wiki/Stress-strain_curve
http://en.wikipedia.org/wiki/Elastic_deformatio
n#Plastic_deformation
http://en.wikipedia.org/wiki/Elastic_deformatio
n#Plastic_deformation
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http://www.metaltech.co.uk/failureanalysis.htm
l
http://www.twi.co.uk/content/oilgas_caseup31.
html
http://www.sv.vt.edu/classes/MSE2094_NoteB
ook/97ClassProj/anal/yue/energy.html
http://www.youtube.com/watch?v=G8oybd2cq
aA
http://www.youtube.com/watch?v=l9BWBiUV
V5g
http://serc.carleton.edu/research_education/equi
libria/other_diagrams.html
http://www.search.com/reference/Steel
http://carsguide.110mb.com/?l=File:Phase_diag
_Fe_C.PNG