paired with lecture 22 - e3
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8/13/2019 Paired With Lecture 22 - E3
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8/13/2019 Paired With Lecture 22 - E3
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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
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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. $.8! Callister 7e.
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Corrosion"
-- the destructive electrocheical attack of a aterial. --#l Capone9s ship! /apona! off the coast of :iini.
Cost" -- 8 to ; of the ross 5ational )roduct &5)'=
-- this aounts to >ust over ?8++ 2illion@yr==
= A.A. Bhlig and .7. 7evie! Corrosion and Corrosion Control: An Introduction toCorrosion Science and Engineering! ,rd ed.! Dohn iley and /ons! 3nc.! 1%$.
==Econoic 7eport of the )resident &1%%$'.
)hotos courtesy 4.M. Maestas! /andia5ational 4a2s. Bsed with perission.
AE CG/ GF CG77G/3G5AE CG/ GF CG77G/3G5
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hat is CG77G/3G5Hhat is CG77G/3G5H
Corrosion is a natural event
It represents a return of metals to their
more natural state as minerals (oxides)
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Metal IantsJ to 2e (irtMetal IantsJ to 2e (irt
ENERGY
METALORE
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:asics of Corrosion:asics of Corrosion
Corrosion is essentially the oxidation of metal
Need:
1. #n #node &where oKidation is taking place'. # Cathode &where reduction is taking place',. Conductive electrolyte8. Electrical contact 2etween the #node and Cathode
Source: Moore, .. Chemical Metallurgy
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ElectrocheistryElectrocheistry
Corrosion is an electrochemical reactionCorrosion is an electrochemical reaction reaction at the anode reaction at the anode:: M MM Mn+n++ ne-+ ne-
Possible reactions at the cathode:Possible reactions at the cathode:
!!+++ e+ e-- ! !
"cid #olutions:"cid #olutions: !!$ + e$ + e-- ! !
+ $!+ $!--
$ $+ !+ !++ + e+ e-- $! $!--
Important thing to note is the flow of electronsImportant thing to note is the flow of electrons
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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
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8/13/2019 Paired With Lecture 22 - E3
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(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
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(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
=
+=
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herodynaics Continuedherodynaics Continued
5ernst 36uation:5ernst 36uation:
'!3 7asic'!3 7asice6uation ,hich describese6uation ,hich describes "%%"%%corrosion reactionscorrosion reactions
)ln(QnF
RTEE o =
/or $ur 3xample:
= +
+
2
2
][
][ln
H
Fe
nF
RTEE o
5ote: p! 2 -lo*089!+
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)our2aiK (iagra)our2aiK (iagra
Potential vs p!Potential vs p!
p! is the measurep! is the measure
of 9!of 9!++ ions in ions in
solutionsolution Map re*ions ofMap re*ions of
thermodnamicthermodnamic
stabilit for metal4sstabilit for metal4s
a6ueous chemicala6ueous chemical
speciesspeciesSource: !!!.corrosionsource.com
http://www.corrosionsource.com/http://www.corrosionsource.com/ -
8/13/2019 Paired With Lecture 22 - E3
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/#5(#7( EMF /E73E//#5(#7( EMF /E73E/
EMF series
#uCu)2/n
5iCoCdFeCr
n#lMg5aN
O1.8+ PO+.,8+- +.16- +.1,6
- +.+- +.- +.8+,- +.88+- +.88
- +.6,- 1.66- .,6,- .18- .%8
etal"
etal
o
oreano
dic
ore
cathodic
Metal with saller
"o
metal corrodes. EK" Cd-5i cell
" *+.1,P
o
-
1.+ M5iOsolution
1.+ MCdOsolution
O
QC 5iCd
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alvanic /eriesalvanic /eriesAB535G5 C3R #E7! AB535G5 C3R #E7! CC
Polts" /aturated Caloel Aalf-Cell 7eference Electrode
O+.8
O+.,
O+.
O+.1 +
-+.1
-+.
-+.,
-+.8
-+.
-+.6
-+.
-+.$
-+.%
-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$el %ase Alloys Conference &roceedings ' ASM ()*+
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Ninetics (escri2es 7ate of 7eactionNinetics (escri2es 7ate of 7eaction
EvanTs (iagraEvanTs (iagra
CORRE
CORRi
CURRENT DENSITY, A/cm
B
B
A
0
0
E
E
ioFe AN
ODIC
ANOD
IC
FeFe
+2 +2e
-
H2H
+ +2e-
2
POTENTIALVOLTS
(SHE)
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
10 10 10 10 10 10 10 10 10-10 -9 -8 -7 -6 -5 -4 -3 -2
CATHODIC
CATHO
DIC
F
e+2 +2e-
Fe
2H+ +2e-
H2
A
for H2on Fe
io
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#rea Effects#rea Effects
MM
+ +e-
ia O
2
Ac
io H+
Aa
O2+H
2O+2e-2OH-
Aaio O2
CreviceEffect
No CreviceEffect
PLUS CreviceEffect
icorrin very
aggresive environment
Log
E
EM/M+
EO
2/OH +
* #rea 3nside Crevice nodic'
* #rea Gutside Crevice &Cathodic'
Aa Ac
AaAc
i
+oi HA c
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8/13/2019 Paired With Lecture 22 - E3
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Effect of GKidi0er Concentration &e.g.! GKygen' on theEffect of GKidi0er Concentration &e.g.! GKygen' on the
Electrocheical :ehavior of an #ctive - )assive MetalElectrocheical :ehavior of an #ctive - )assive Metal
Log i
MM+
[ontanna and Greene! Corrosion Engineering! M"Gra#$%ill! &'()*
3ncreasing GKidantConcentration
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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$el %aseAlloysConference &roceedin's-AS() *+5,
./0 ./1./2./
)
.-./)-./2 -./1-./0-.
/5
-./-./3-.
/+
-./*-)/.-
)/)
-)/2-)/1-)/0-)/5-)/ -)/3-)/+
(a'nesium(an'aneseAlumi num4incCadmiu meadAlloy25567erralium8Hi'h&urity9ronCo::erAl loy&E2Alloy2-)"2-));0Ca r!onSteel(
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ypes of #queous Corrosion Cellsypes of #queous Corrosion Cells
1eneral Corrosion1eneral Corrosion %ocali.ed Corrosion%ocali.ed Corrosion
Pittin*Pittin*
Crevice CorrosionCrevice Corrosion;nder-deposit Corrosion;nder-deposit Corrosion
MICMIC
'uberculation'uberculation 1alvanic Corrosion1alvanic Corrosion
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eneral Corrosioneneral Corrosion
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eneral Corrosioneneral Corrosion
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eneral Corrosioneneral Corrosion
Griginal /urface
)enetration due to Corrosion
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4ocali0ed Corrosion4ocali0ed CorrosionCar2on /teelCar2on /teel
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4ocali0ed Corrosion4ocali0ed CorrosionCar2on /teelCar2on /teel
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4ocali0ed Corrosion4ocali0ed Corrosion
#tationar 3lectrodes#tationar 3lectrodes
"ll of the dissolution occurs"ll of the dissolution occurs
in one locationin one location
ei*ht loss measurement ei*ht loss measurement
not usefulnot useful
%ocal Penetration%ocal Penetration
#ometimes local ,ea&enin*#ometimes local ,ea&enin*
Ma or ma not =eopardi.eMa or ma not =eopardi.e
structural inte*ritstructural inte*rit etermines >failure?etermines >failure?
Volts:S aturatedCalomelHalf-CellR eferenceElectr ode
Galvan icSeries-ConcentratedHydro chloricAcidat2 5CCrumandS car!erry"Corrosionof#ic$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(
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)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(
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