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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

1

Materials Science

• Engineers must choose the correct materials

for each purpose and use.

• The properties, strengths and weaknesses,

must be understood.

2

Many types of materials

• Iron

• Steel

• Glass

• Plastics

• Rubber

• Semiconductors

3

• Physical Properties

• Chemical Properties

• Nuclear Properties

4

Types of Materials

• Metals

• Non-metals

• Ceramics

• Polymers

5

Periodic Table

6

• Metals – release their electrons

• Non-metals – accept or share electrons,

usually form molecules or anions

7

• 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.

8

Types of Materials

• Metals

• Non-metals

• Ceramics

• Polymers

9

The Atom

10

Bonding in Solids

• Interatomic forces

• Coulombic attractive & repulsive

• Ionic – electron transfer

• Covalent – electron sharing

• Metallic – sharing large numbers of free electrons

11

Bonding in Solids

• Ionic – Ceramics

• Covalent – Polymers & Semiconductors

• Metallic - Metals

12

Long range order or not

• Crystalline

• Amorphous

– Liquids, glass, plastics

13

Crystals

14

Metals

• Crystallize during solidification

• Iron

• Steel

• Aluminum

15

Steel

16

Steel

• Iron

• Carbon

• Other Alloying Agents

– manganese, chromium, vanadium, and tungsten

Fe 26

56

C 6

12

17

• “Carbon and other elements act as a

hardening agent, preventing dislocations in

the iron atom crystal lattice from sliding

past one another.” wikipedia

18

Mechanical Properties

• Stress

• Strain

• Strength

– Yield

– Tensile

• Ductility

• Toughness

• Hardness

19

Mechanical Properties

• Affected by:

– Alloying agents

– Crystal defects

– Grain size and grain boundaries

20

Steel

• Internal Structure

• Crystal Lattice

• Alloy

– Substitution

– Interstitial

• Grains 21

Crystallize

• During solidification

22

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.

23

Grains

• The structure in a solidified metal

• Single crystals that are next to each other

• Grain Boundaries – between grains

24

Zinc plating 25

Steel grains

microscopic

26

Defects in Crystal Lattice

• Point Defects

– Vacancies

– Interstitial atom

• Line Defects

– Edge dislocations

27

• “Carbon and other elements act as a

hardening agent, preventing dislocations in

the iron atom crystal lattice from sliding

past one another.” wikipedia

28

Diffusion

• Atoms and Vacancies

• Heat Treatments: Annealing

• Change metal properties

29

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

30

Mechanical Properties

• Affected by:

– Alloying agents

– Crystal defects

– Grain size and grain boundaries

31

Mechanical Properties

• Stress

• Strain

• Strength

– Yield

– Tensile

• Ductility

• Toughness

• Hardness

32

Explain

• Stress

• Strain

• Toughness

• Elastic Deformation

• Plastic Deformation

• Ductile Failure

• Brittle Failure

• Fatigue Failure

• Creep

33

Testing Metal Properties

• Tension Test

• Charpy Test - Impact Energy

34

Stress – Strain using Tensometer

35

Rebar

ASTM A36

Tensile Test Illustration

Young's Modulus Illustration

36

Stress vs. Strain curve for structural steel

37

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

38

Stress

A

F

39

Strain

• Deformation

L

L

40

Str

ess

Strain

Yield Strength

Ultimate Strength

Fracture

Elastic

Plastic

41

42

Str

ess

Strain

Yield Strength

Ultimate Strength

Fracture

Elastic

Plastic

43

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

44

Elastic Deformation

• Reversible

• Hooke’s Law: springs

• E is a material constant called Young's

modulus [the spring constant]

E

45

Plastic Deformation

• Not reversible

46

Ductility

• Extent to which materials can be deformed

plastically without fracture

47

Ductile Failure

• Extensive plastic deformation takes place

before fracture

48

Brittle Failure

• No apparent plastic deformation takes place

before fracture

49

Fatigue Failure

• Progressive and localized structural damage

that occurs when a material is subjected to

cyclic loading.

50

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.

51

Testing Metal Properties

• Tension Test

• Charpy Test - Impact Energy – Related to

toughness

52

Charpy Test Video

Charpy Test Video

53

Testing Metal Properties

• Tension Test

• Charpy Test - Impact Energy – Related to

toughness

54

Phase Diagrams

55

Explain

• Stress

• Strain

• Toughness

• Elastic Deformation

• Plastic Deformation

• Ductile Failure

• Brittle Failure

• Fatigue Failure

• Creep

56

Problem with calculations

57

58

Homework for next week

• Required

• Optional

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

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

61

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

62

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

63

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