Paired With Lecture 22 - E3

8/13/2019 Paired With Lecture 22 - E3

1/27


2/27

Fatigue liit! Sfat"--no fatigue if S< Sfat

#dapted fro Fig.$.1%&a'! Callister 7e.

Fatigue (esign )araetersFatigue (esign )araeters

Sfat

case forsteel &typ.'

N* Cycles to failure1+, 1+ 1+ 1+%

unsafe

safe

S* stress aplitude

/oeties! the fatigue liit is 0ero

#dapted fro Fig.$.1%&2'! Callister 7e.

case for#l &typ.'

N* Cycles to failure

1+,

1+

1+

1+%

unsafe

safe

S* stress aplitude


3/27

3proving Fatigue 4ife3proving Fatigue 4ife

1. 3pose a copressive surface stress &to suppress surface cracks fro growing'

5 * Cycles to failure

oderate tensile m4arger tensile m

/ * stress aplitude

near 0ero or copressive m3ncreasing

m

--Method 1" shot peening

putsurface

intocopression

shot--Method " car2uri0ing

C-rich gas

. 7eove stress concentrators. #dapted fro

Fig. $.! Callister 7e.

2ad

2ad

2etter

2etter

#dapted froFig. $.8! Callister 7e.


4/27

Corrosion"

-- the destructive electrocheical attack of a aterial. --#l Capone9s ship! /apona! off the coast of :iini.

Cost" -- 8 to ; of the ross 5ational )roduct &5)'=

-- this aounts to >ust over ?8++ 2illion@yr==

= A.A. Bhlig and .7. 7evie! Corrosion and Corrosion Control: An Introduction toCorrosion Science and Engineering! ,rd ed.! Dohn iley and /ons! 3nc.! 1%$.

==Econoic 7eport of the )resident &1%%$'.

)hotos courtesy 4.M. Maestas! /andia5ational 4a2s. Bsed with perission.

AE CG/ GF CG77G/3G5AE CG/ GF CG77G/3G5


5/27

hat is CG77G/3G5Hhat is CG77G/3G5H

Corrosion is a natural event

It represents a return of metals to their

more natural state as minerals (oxides)


6/27

Metal IantsJ to 2e (irtMetal IantsJ to 2e (irt

ENERGY

METALORE


7/27

:asics of Corrosion:asics of Corrosion

Corrosion is essentially the oxidation of metal

Need:

1. #n #node &where oKidation is taking place'. # Cathode &where reduction is taking place',. Conductive electrolyte8. Electrical contact 2etween the #node and Cathode

Source: Moore, .. Chemical Metallurgy


8/27

ElectrocheistryElectrocheistry

Corrosion is an electrochemical reactionCorrosion is an electrochemical reaction reaction at the anode reaction at the anode:: M MM Mn+n++ ne-+ ne-

Possible reactions at the cathode:Possible reactions at the cathode:

!!+++ e+ e-- ! !

"cid #olutions:"cid #olutions: !!$ + e$ + e-- ! !

+ $!+ $!--

$ $+ !+ !++ + e+ e-- $! $!--

Important thing to note is the flow of electronsImportant thing to note is the flow of electrons


9/27

herodynaic (riving Forceherodynaic (riving Force

%i&e all chemical reactions 'hermodnamics%i&e all chemical reactions 'hermodnamics

hat is the drivin* force for the reactionhat is the drivin* force for the reaction(other,ise stated as ,hat is the electrochemical(other,ise stated as ,hat is the electrochemicalpotential for the reaction)potential for the reaction)

issimilar metalsissimilar metals ifferent cold ,or& statesifferent cold ,or& states

ifferent *rain si.esifferent *rain si.es

ifference in local chemistrifference in local chemistr

ifference in the availabilit of species for a reactionifference in the availabilit of species for a reaction

(concentration cells)(concentration cells) ifferential aeration cellsifferential aeration cells


10/27

(erivation of 5ernst Equation(erivation of 5ernst Equation

+ + eFeFe 22

+=+=

tsreac

productsoo

aaRTGQRTGG

tan

ln)ln(

)(22 2 gHeH + +

/or:

)(2 22

gHFeHFe ++ ++

[ ]

+=

+= +

+

+

+

2

2

2

2

2

][

][ln

)()(

)()(ln

H

FeG

HaFea

HfFeaGG oo

0

0


11/27

(erivation of 5ernst EquationL(erivation of 5ernst EquationL

Introduce: 'he total electropotential isIntroduce: 'he total electropotential is 1 2 -n/31 2 -n/3

here:here: / 2 /arada4s constant (total char*e on "vo*adro4s number of electrons)/ 2 /arada4s constant (total char*e on "vo*adro4s number of electrons)

n 2 the number of electrons transferredn 2 the number of electrons transferred3 2 'he electrode potential3 2 'he electrode potential

)ln(

)ln(

QRTnFEnFE

or

QRTnFEnFE

o

o

=

+=


12/27

herodynaics Continuedherodynaics Continued

5ernst 36uation:5ernst 36uation:

'!3 7asic'!3 7asice6uation ,hich describese6uation ,hich describes "%%"%%corrosion reactionscorrosion reactions

)ln(QnF

RTEE o =

/or $ur 3xample:

= +

+

2

2

][

][ln

H

Fe

nF

RTEE o

5ote: p! 2 -lo*089!+


13/27

)our2aiK (iagra)our2aiK (iagra

Potential vs p!Potential vs p!

p! is the measurep! is the measure

of 9!of 9!++ ions in ions in

solutionsolution Map re*ions ofMap re*ions of

thermodnamicthermodnamic

stabilit for metal4sstabilit for metal4s

a6ueous chemicala6ueous chemical

speciesspeciesSource: !!!.corrosionsource.com
http://www.corrosionsource.com/http://www.corrosionsource.com/


14/27

/#5(#7( EMF /E73E//#5(#7( EMF /E73E/

EMF series

#uCu)2/n

5iCoCdFeCr

n#lMg5aN

O1.8+ PO+.,8+- +.16- +.1,6

- +.+- +.- +.8+,- +.88+- +.88

- +.6,- 1.66- .,6,- .18- .%8

etal"

etal

o

oreano

dic

ore

cathodic

Metal with saller

"o

metal corrodes. EK" Cd-5i cell

" *+.1,P

o

-

1.+ M5iOsolution

1.+ MCdOsolution

O

QC 5iCd


15/27

alvanic /eriesalvanic /eriesAB535G5 C3R #E7! AB535G5 C3R #E7! CC

Polts" /aturated Caloel Aalf-Cell 7eference Electrode

O+.8

O+.,

O+.

O+.1 +

-+.1

-+.

-+.,

-+.8

-+.

-+.6

-+.

-+.$

-+.%

-1.+

-1.1

-1.

-1.,

-1.8

-1.

-1.6

-1.

-1.$

MagnesiuManganese

Cast 3roninc

#luinu#luinu #lloy +

Mild /teelin4ead

5ickel - /ilverCopper

#lloy +C2,#lloy 1$-1$-

:rass #lloys#lloy ,7E6++ - ,+ Copper-5ickel%+ - 1+ Copper-5ickel#lloy EFE6

:ron0e #lloys#lloy 6S#lloy 1-8)A#lloy &ferralliu'#lloy ,+ &Coronel'

#lloy 6-1! 6-1 - 1@8#lloys C6! ! S

#lloy 8 /4SMG5E4 alloys 8++! 78+! N++

#lloy :! )! )( &3lliu'35CG4GR alloy $++! $! $8+

5ickel ++! +/tainless /teel ,+8! ,16! ,1! 8+,

35CG5E4 alloys 6++! 61! 61$! 6! 61! 6%+! +! S+itaniu

#lloy ++ &Dessop'

O+.68 - +.6P )latinu

Source: Crum and Scar#erry, Corrosion of Nic$el %ase Alloys Conference &roceedings ' ASM ()*+


16/27

Ninetics (escri2es 7ate of 7eactionNinetics (escri2es 7ate of 7eaction

EvanTs (iagraEvanTs (iagra

CORRE

CORRi

CURRENT DENSITY, A/cm

B

B

A

0

0

E

E

ioFe AN

ODIC

ANOD

IC

FeFe

+2 +2e

-

H2H

+ +2e-

2

POTENTIALVOLTS

(SHE)

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

10 10 10 10 10 10 10 10 10-10 -9 -8 -7 -6 -5 -4 -3 -2

CATHODIC

CATHO

DIC

F

e+2 +2e-

Fe

2H+ +2e-

H2

A

for H2on Fe

io


17/27

#rea Effects#rea Effects

MM

+ +e-

ia O

2

Ac

io H+

Aa

O2+H

2O+2e-2OH-

Aaio O2

CreviceEffect

No CreviceEffect

PLUS CreviceEffect

icorrin very

aggresive environment

Log

E

EM/M+

EO

2/OH +

* #rea 3nside Crevice nodic'

* #rea Gutside Crevice &Cathodic'

Aa Ac

AaAc

i

+oi HA c


18/27

Effect of GKidi0er Concentration &e.g.! GKygen' on theEffect of GKidi0er Concentration &e.g.! GKygen' on the

Electrocheical :ehavior of an #ctive - )assive MetalElectrocheical :ehavior of an #ctive - )assive Metal

Log i

MM+

[ontanna and Greene! Corrosion Engineering! M"Gra#$%ill! &'()*

3ncreasing GKidantConcentration


19/27

Effect ofEffect of eperatureeperatureand (issolved Gand (issolved G

Vo lts:SaturatedC alomelHalf-C ellRefer enceElectrode

Ga lvanicSeries- ConcentratedH ydrochlor icAcidat25CCruma ndScar!erry"Corrosion of#ic$el %aseAlloysConference &roceedin's-AS() *+5,

./0 ./1./2./

)

.-./)-./2 -./1-./0-.

/5

-./-./3-.

/+

-./*-)/.-

)/)

-)/2-)/1-)/0-)/5-)/ -)/3-)/+

(a'nesium(an'aneseAlumi num4incCadmiu meadAlloy25567erralium8Hi'h&urity9ronCo::erAl loy&E2Alloy2-)"2-));0Ca r!onSteel(


20/27

ypes of #queous Corrosion Cellsypes of #queous Corrosion Cells

1eneral Corrosion1eneral Corrosion %ocali.ed Corrosion%ocali.ed Corrosion

Pittin*Pittin*

Crevice CorrosionCrevice Corrosion;nder-deposit Corrosion;nder-deposit Corrosion

MICMIC

'uberculation'uberculation 1alvanic Corrosion1alvanic Corrosion


21/27

eneral Corrosioneneral Corrosion


22/27



23/27


Griginal /urface

)enetration due to Corrosion


24/27

4ocali0ed Corrosion4ocali0ed CorrosionCar2on /teelCar2on /teel


25/27

4ocali0ed Corrosion4ocali0ed CorrosionCar2on /teelCar2on /teel


26/27

4ocali0ed Corrosion4ocali0ed Corrosion

#tationar 3lectrodes#tationar 3lectrodes

"ll of the dissolution occurs"ll of the dissolution occurs

in one locationin one location

ei*ht loss measurement ei*ht loss measurement

not usefulnot useful

%ocal Penetration%ocal Penetration

#ometimes local ,ea&enin*#ometimes local ,ea&enin*

Ma or ma not =eopardi.eMa or ma not =eopardi.e

structural inte*ritstructural inte*rit etermines >failure?etermines >failure?

Volts:S aturatedCalomelHalf-CellR eferenceElectr ode

Galvan icSeries-ConcentratedHydro chloricAcidat2 5CCrumandS car!erry"Corrosionof#ic$el%aseAlloysCon ference&roceedin's-A S()*+5,

./0./1

./2

./).-./)-./2-./1-

./0

-./5-./-./3-./+-./* -)/.-)/)-)/2-)/1-)/0-)

/5

-)/-)/3-)/+(a'n esium(an'aneseAluminum4incCadmiumeadAlloy25567e rralium8Hi'h&urity9ronCo::erAlloy&E2Alloy2-)"2-)); 0Car!onSteel(


27/27

)otential and Current Fields in Electrolyte in)otential and Current Fields in Electrolyte in

the Picinity of a 4ocali0ed Corrosion /itethe Picinity of a 4ocali0ed Corrosion /ite

Vo lts:SaturatedC alomelHalf-C ellRefer enceElectrode

Ga lvanicSeries- ConcentratedH ydrochlor icAcidat25CCruma ndScar!erry"Corrosion of#ic$el %aseAlloysConference &roceedin's-AS() *+5,

./0 ./1./2./

)

.-./)-./2 -./1-./0-.

/5

-./-./3-.

/+

-./*-)/.-

)/)

-)/2-)/1-)/0-)/5-)/ -)/3-)/+

(a'nesium(an'aneseAlumi num4incCadmiu meadAlloy25567erralium8Hi'h&urity9ronCo::erAl loy&E2Alloy2-)"2-));0Ca r!onSteel(

Paired With Lecture 22 - E3

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