Corrosion 1

82 CORROSION TESTING

HYPOTHETICAL CATHODIC AND ANODIC POLARIZATION DIAGRAM - + -

8 OBSERVED POLARIZATION PLOT

CORROSION

ANODIC BRANCH

OPEN CIRCUIT POTENTIAL

W L

5 - I

LOG CURRENT DENSITY

Source: ASTM, Q 3, Fig. 3 (2000 Edition). Reprinted, with perm~ssion, copyright ASTM.

CORROSION TESTING 83

TYPICAL CATHODIC AND ANODIC POLARIZATION DIAGRAM

POLARIZATION BEHAVIOR OF STEEL IN 1.ON Na, SO,

100 10’ 1 02

CURRENT DENSITY (pAkrn2)

Source: R. Baboian


HYPOTHETICAL CATHODIC AND ANODIC POLARIZATION PLOTS FOR A PASSIVE ANODE

LOG CURRENT DENSITY

Source: ASTM, 0 3, Fig. 4, (2000 Edition). Reprinted, with permission, copyright ASTM.


TYPICAL STANDARD POTENTIOSTATIC ANODIC POLARIZATION PLOT

1.60

1.40

1.20

1 .oo

G 0.80 8 9 0.60

$ 0.40 v - g 0.20

g 0.00 3

-0.20

-0.40

Type 430 Stainless Steel (543000)

1 N H2SO4,3OoC

Potentiostatic 50 mV each 5 min

-0.60 I 1 1 1 1 1

0.1 1 .o 10 lo2 103 104 lo5 Current Density (pA/cm2)

Source: ASTM, 0 5, Fig. 4 (2000 Edition). Reprinted, with permission, copyright ASTM


DATA FOR TAFEL EQUATION CALCULATIONS i

q=p10g- 10

Temwratun P 10 ‘I Metal “C Solution volts A/m2 [I mA/cm* MI’

Pt (smooth)

Pd Mo Au Ta w Ag Ni

Bi Nb Fe

c u

Sb Al Be Sn Cd Zn Hg

Pb

Pt (smooth)

AU

Zn c u Fe Ni

20 25 20 20 20 20 20 20 20 20 20 20 16 25 20 20 20 20 20 20 16 20 20 20 20 20

20 20 20

25 25 25 25

Hydrogen Overvoltage

I N HCI 0.1N NaOH O.6N HCI I N HCi I N HCI 1N HCI 5N HCI

0. lN HCI 0.1N HCI

0.12N NaOH 1N HCI I N HCI I N HCI

4% NaCl pH 1-4 0.1 N HCI

0.15N NaOH 2N HzS04 2N H2S04

I N HCi I N HCI 1N HCI

1 N H2S04 0.IN HCI

0.1N H2S04 0.1N NaOH 0.01-8N HCI

0.03 0.11 0.03 0.04 0.05 0.08 0.11 0.09 0.10 0.10 0.10 0.10 0.15 0.10 0.12 0.12 0.10 0.10 0.12 0.15 0.20 0.12 0.12 0.12 0.10 0.12

Oxygen Overvoltage

0.1N H2S04 0.10 0.IN NaOH 0.05 0.1 N NaOH 0.05

Metal Overvoitage (deposition)

1 M &SO4 0.12 1M CuS04 0.12 1 M FeSO, 0.12 1 M NiS04 0.12

‘1 rnA/cm2 = 10 A h 2

Source: H. H. Uhlig, Corrosion and Corrosion Control, 3rd ed., p. 44, John Wiley 8 Sons. Copyright 01985. This material is used by permission of John Wiiey 8 Sons, Inc.

10 0.68

2 10-2 10-2 lo-’ lo-’

5 10-3 8 10-3 4 10-3

10-3 10-3 10-2 10-3

2 10-3 1 x 10-2

10-5 10-6 10-5 i 0-4 10-3

1.6 10-7 7 10-9 2 10-9 3 x lo - ” 2 10-9

9 x 10-8 4 x 10-8 5 10-9

0.2 0.2

10-4 2 10-5

0.00 0.13 0.02 0.12 0.15 0.16 0.22 0.30 0.31 0.34 0.40 0.40 0.45

0.44 0.36 0.60 0.70 0.72 0.75 0.80 0.94 1.10 1.16 1.15 1.16

0.40 (Stern)

0.81 0.47 0.47

0.20 (Bockris) 0.20 (Bockris) 0.60 (Bockrls) 0.68 (Bockris)


HYPOTHETICAL POLARIZATION RESISTANCE PLOT

4 h

v _ _ + i

4 : I I

(4

/'

Source: ASTM. G 3, Fig. 2 (2000 Edition). Reprinted, with permission, copyright ASTM


POLARIZATION RESISTANCE METHOD FOR DETERMINING CORROSION RATES

Defining the polarization resistance R, as

and combining the constants as

B= b.b, P.303(ba + b,)

the corrosion current icon can be calculated as

The dimension of R, as determined from a potential-current plot is ohms (a). In order to obtain a value of R,, which is independent of the electrode surface and which can be converted into Corrosion rates, polarization resistance values should be reported in R .om2 (e.g., mV/mA/cm2).

See following page for typical values for constant B.

Source: F, Mansfieid in Electrochemical Techniques for Corrosion. R. Baboian, Editor, NACE, pp. 18-26,1977.


VALUES OF THE CONSTANT B FOR THE POLARIZATION RESISTANCE METHOD

Theoretical (Values of 8 calculated from arbitrary b. and b, values using formula on previous page: b, and b, values can be interchanged.)

Iron, 4% NaCI, pH 1.5 Iron, O.5N H2S04, 30 C Iron, IN H2S04 Iron, I N HCI Iron, 0.02M citric acid, pH 2.6. 35 C Carbon steel, seawater Carbon steel. 1N Na2S04, H2, pH 6.3,30 C 304L SS, 1N HzSOI, 0 2

304 SS, lithiated water, 288 C 304 SS, 3% NaCI, 90 C 430 SS. I N HzSOl, HP, 30 C 600 alloy, iithiated water, 268 C A1 1199. I N NaCI, pH 2,30 C Aluminum, seawater Zircaloy 2, lithiated water, 288 C OFHC Copper, I N NaCI, HP, pH 6.2. 30 C

30 30 30 30 30 60 60 60 60 60 90 90 90 90 120 120 180 180

57

inf. 65 inf.

82

45 inf.

30 60 120 180 m 60 90 120 160 ‘x 90 120 180

120

180 m

m

s

m

50 160 50

160

600 186

6.5 9 10 1 1 13 13 16 17 20 26 20 22 26 39 26 52 39 78 17 17

10-20

12 25 19 22 24 22 20 24 44 18 81 26

I a23

Source: Adapted from a collection of literature values compiled by Florian Mansfeld, Electrochemical Techniques for Corrosion, R. Baboian, Editor, NACE, pp, 18, 26, 1977.


HYDROGEN OVERVOLTAGE ON VARIOUS ELECTRODE MATERIALS

2

1

0

-1

t -2

NE -3 Y 9 8 - 4

8 -I

-5

-6

-7

-8

-9 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0

11 (4 - Source: C. A. Hampel.


STANDARD REFERENCE POTENTIALS AND CONVERSION TABLE

REFERENCE POTENTIALS

Potential M 0 25%

Electmde

Thermal Temperature Coefficient'

(mVPC)

(R)/Hz (a = 1)/H + (a = 1) (SHE) Ag/AgCI/l M KCI Ag/AgC1/0,6M CI-

(seawater) Ag/AgCI/O.l M CI- Hg/HgzCIz/sat KCI (SCE) HS/HgzCIz/l M KCI Hg/HgzCl2/0.1M KCI Cu/CuS04sat Hg/HgzSOdHzSO,

0.000 ... +0.235 ... +0.25 ... +0.288 ... t0.241 t0.244 +0.280 +0.283 +0.334 +0.336 +0.30 ... +0.616 ...

f0.87 +0.25 ... +0.22 f0.22 +0.59 +0.79 +0.90 +0.09

(')To convert from thermal to isothermal temperature coefficients, subtract 0.87 mV/°C.

(b)E' is the standard potential for the half cell corrected for the concentration of the ions. (c)E" also includes the liquid junction potentials for a saturated KCI salt bridge.

Thus the isothermal temperature coefficient for Ag/AgCVlM KCi is -0.62 mV/'C.

CONVERSION FACTORS")

From (E') To SHE Scale To SCE Scale ( E )

Hz/H+ Ag/AgCVl M KCI Ag/AgCVOBM CI-

(seawater) Ag/AgCVO.lM CI- Hg/HgzClz/sat KCI (SCE) Hg/HgzClz/IM KCI Hg/Hg2Clz/O.lM KCI cu/cuso4 sat Hg/Hgz SOdHz SO4

... +0.235 +0.25

f0.288 +0.241 +0.280 +0.334 +0.30 +0.616

-0.241 -0.006 +0.009

+0.047

+0.039 +0.093 i-0.06

...

... (d)To convert from one scale to another, add the value indicated.

Example: An electrode potential of +l.OOOV versus SCE would be (1,000 + 0.241) = +1.241V versus SHE. An electrode potential of -1 .OOOV versus SCE would give (-1.000 + 0.241) = -0.759V versus SHE.

Source: ASTM, G 3, (2000 Edition). Reprinted, with permission. copyright ASTM

(0 h) ELECTROCHEMICAL SERIES

REDUCTION REACTIONS HAVING E" VALUES MORE POSITIVE THAN THAT OF THE STANDARD HYDROGEN ELECTRODE a Reaction E",V Reaction

2 H+ +2e$H2 Cul- +e$Cu+21- Ge'+ + 2 e $ G$+ NO; +Hz0+2e$NO;+2H0 n203 + 3 H20 + 4 e $ 2 n+ + 6 0 H S e - +H20+2e:%0- +20H- UW +e$UO; Pd(0Hk + 2 e $ Pd + 2 OH- AgBr+e $ Ag + Brr s,@- + 2 e: 2 s.&- AgSCN + e - Ag + SCN- NZ +2H20+6Ht +6e$2NH40H HgO + H20 + 2 e $ Hg + 2 OH- lr203 + 3 H20 + 6 e $ 2 lr + 6 0 H 2 NO + 2 e $ N2@- [Co(NH~)s13' + e $ [CO(NH3!&+ Hg20 + H20 + 2 e $2 Hg + 2 OH Ge4+ + 4 e $ G e HgzBr2 + 2 e s 2 Hg + 2 Br- Pt(OH)2 + 2 e 2 Pt + 2 OH- S + 2 H+ + 2 e $ H2S(aq) Np4+ + e $ Np3+ AgdFe(CN)d + 4 e $ 4 Ag + [Fe(CNkI4 Mn(OH)3 + e $ Mn(OH)2 + OH- 2 NO; + 3 H20 + 4 e $ N20 + 60H- Sn4' +2e$Sn2+ SbO, + 6 Hf + 6 e $ 2 Sb + 3 H20 Cu2+ + e : Cut

o.ooooo 0.00 0.00 0.01 0.02 0.05 0.062 0.07 0.07133 0.08 0.8951 0.092 0.0977 0.098 0.10 0.108 0.123 0.124 0.13923 0.14 0.142 0.147 0.1478 0.15 0.15 0.151 0.152 0.153

BiOC1+2 H+ + 3 e $ & + CI- +HzO Bi(CI); + 3 e $ Bi + 4 CI- WOHh + e S Co(0Hk + OH- S@- + 4 H+ + 2 e $ H2S03 + Hz0 SbO+ + 2 H+ + 3 e $ Sb + 2 H20 AgCl + e $ Ag + CI- As20,+6H+ + 6 e z 2 A s + 3 H 2 0 Calomel electrode, Saturated NaCl (SSCE) &++2e:Ge Calomel electrode. saturated KCI PbOz + HzO + 2 e $ PbO + 20H- HASO, + 3 H+ + 3, $ As + 2 Hz0 Flu3+ + e $ Ru2+ Re02 + 4 H+ + 4 e z Re + 2 H20 10; + 3 H Z 0 + 6 e $ l - +OH- Hg2Clz + 2 e $ 2 Hg + 2 CI- Calomel electrode, molal KCI Calomel electrode. 1 moVl KCI (NCE) Re3++3e$Re BiO+ +2H+ + 3 e $ B i + H 2 0 UOF + 4 H+ + 2 e = U4+ + 2 H20 CIO; + HZO + 2 e $ CIO; + 2 OH- 2 HCNO + 2 H+ + 2 e $ (CN)2 + 2 H20 Calomel electrode, 0.1 moVl KCI V@+ + 2 H+ + e 2v+ + HZO C u 2 + + 2 e s C u Ag20 + HZO + 2 e $ 2 Ag + 2 OH- Cd+ + 2 e $ Cu(Hg)

E-, V 6 ~

0.1583 3 8 0.16

0.17

0.212 21 0.172 2

2 0.22233 0.234 0.2360 -i

0.2412 Q 0.24 2 0.247 ~~

0.248 0.2487 0.2513 0.26 0.26808 0.2800 0.2801 0.300 0.320 0.327 0.33 0.330 0.3337 0.337 0.3419 0.342 0.345

Reaction

~ g ~ + e s 4 + 1 o ; [Fe(CN)613- + e + [Fe(C&I'- Cloy + H20 + 2 e e CIO; + 2 OH- AgzSeos + 2 e $ 2 Ag + S d 3 - ReO; +8H+ + 7 e e R e + 4 H 2 0 (CNh+2H+ + 2 e e 2 H C N [Ferricinium]+ + e $ fermcene Tc2+ + 2 e $ Tc 02 + 2 HZO + 4 e $ 4 OH- &oCN + e $ Ag + W N - [RhCI6l3- + 3 e S Rh + 6 CI- &~CIO, + 2 e e 2 ~g + c e - H2S& + 4 H+ + 4 e $ S + 3 H20 Flu2+ + 2 e $ R u Ag2Mo04 + 2 e $ 2 Ag + MOO- AgzC204 + 2 e $ 2 Ag + Se- As2W0, + 2 e $ 2 4 + W e - &C03 + 2 e s 2 ~g + Ccf- Td; +8H+ +7e=Te+4H20 10- + H20 + 2 e = I- + 2 OH- ReO; + 4 H+ + 3 e $ Re02 + 2 HZO Hgz(ack + 2 e $ 2 Hg + 2 (ac- Cu+ + e $ Cu l 2 + 2 e $ 2 I - l 3 + 2 e $ 3 I - AgBQ + e$Ag + 610; MnO; + e = Mne- H 3 M 4 + 2 H+ + 2 e- $ HAs02 + 2 H20 10; + 2 H 2 0 + 4 e e I O - +40H- S&+4H++2e$2H2S03 A g N q + e$Ag + NO; Te4+ + 4 e g Te S ~ O 5 + 6 6 + + 4 e $ 2 S b O + + 3 H 2 0 RuO; + e e Rue- FdCLI2- + 2 e $ Pd + 4 CI- T302 + 4 H+ + 4 e = Te + 2 H20

Eo.V

0.354 0.358 0.36 0.3629 0.368 0.373 0.400 0.400 0.401 0.41 0.431 0.4470 0.449 0.455 0.4573 0.4647 0.4660 0.47 0.472 0.485 0.510 0.51 163 0.521 0.5355 0.536 0.546 0.558 0.560 0.56 0.564 0.564 0.568 0.581 0.59 0.591 0.593

Reaction €0. V

MnO; + 2 H20 + 3 e $ Mn02 + 4 OH- Rh2++2e$Rh Rh++e$Rh M e - +2H20+2e$Mn@ +40H- 2 Ago + H20 + 2 e S Ag20 + 2 OH- 610; +3H20+6e=Br r +6OH- UO; + 4 H+ + e $ U4+ + 2 H 2 0 Hg,S04 + 2 e $ 2 Hg + ?O- CIO; + 3 H 2 0 + 6 e S C I - +6OH- Hg2HP04 + 2 e $2 Hg + H P e - A g W + e S Ag + (aW SbOs (valentinite) + 4 H+ + 4 e e Sb& + 2 HzO

CO; + H20 + 2 e $ CIO- +2OH- SbOs (senarmontite) + 4 H+ + 4 e $ SkO3 + 2 H20 [aC16]'- + 2 e $ [p1c14p- + 2 CI- O2 + 2 H+ + 2 e $ H202 pbenzoquincme + 2 H+ + 2 e : hydmquinone H3i06 + 2 e $10; + 3 OH- Ag& + H20 + 2 e = SAgO+ 2 OH- pCL]2- + 2 e = Pt + 4 c i - Rh3+ + 3 e $ Rh CIO; +2H20+4e$CI - + 4 0 H - 2 NO+ H20 + 2 e $ N20+ 20H- B r O - + H 2 0 + 2 e e B r +20H- ReO; + 2 H+ + e $ ReO, + H20 (CNSk + 2 e S 2 CNS- [lrCl6F- + 3e $ lr + 6 CI- Fe3+ + e $ F&+ Ag(F) + e $Ag + F TcO-+4H++3eeTc02+2H20 Hg$ + 2 e S 2 H g Ag++e$Ag 2 NO; + 4 H+ + 2 e $ N20, + 2 H20 CIO- + H20 + 2 e $ CI- + 2 OH- Os04+8H+ + 8 e $ O s + 4 H 2 0

+ 2 e s 2 ~g + .%3-

0.595 0.600 0.600 0.60 0.607 0.61 0.612 0.6125 0.62 0.6359 0.643 0.649 0.654 0.66 0.671 0.68 0.695 0.6992 0 0.7 0.739 0.755 0.758 0.76 0.76 0.761

0.77 0.77 0.771 0.779 0.782 0.7973 0 0.7996 0.803 (D 0.841 0 0.85

B 8

El 3

b

6 0.768 2

(Continued)

ELECTROCHEMICAL SERIES (Continued)

HgZ++2e$Hg AuBr; + 3 e $ Au + 4 Br- SiOz (quattz) + 4 H+ + 4 e $Si + 2 H20 2 HN0z + 4 H+ + 4 e $ H2Nz@ + HzO [lrc16]'- + e orc16]3- Nz04 + 2 e $ 2 NO; HO; + H Z O + 2 e $ 3 0 H 2 Hg2+ + 2 e $ Hg? NO- + 3 H+ + 2 e 2 HNOz + Hz0 Pd2+ + 2 e $ P d CIOZ (aq) + e ClO; NO; +4H+ + 3 e = N O + 2 H 2 0 AuBr; + e 2 Au + 2 Br- HN02 + H' + e $ NO+ HzO H l O + H + + 2 e $ l - +HzO VO; + 2 H+ + e $ V b + + HzO Ru04 + e $ RuO; V(OH): + 2 H+ + e =V@+ + 3 HzO

pd+ + e $ Pd+ AUCI; + 3 e 2 Au + 4 CI-

H6Te06 + 2 H+ + 2 e $TeOz + 4 HzO NzOd + 4 H+ + 4 e 2 NO + 2 HzO p?(phen)3I3+ + e $ [Fe(phen)#' (1 (mol/l H2S04) PuOz(0H)z + H+ + e $ PuOZOH + HzO

Brz(l) + 2 e $ 2 Br- 10; + 6H+ + 6 e $ I- + 3 HzO Srz(aq)+2e$2Br- pu5+ + e $ Pu4+ CuZ+ + 2 CN- + e R ~ O Z + ~ H + + ~ ~ $ R U ~ + + Z H ~ O [Fe@henanthr~lineh]~+ + e 2 [Fe(phen)3I2' .S& + 4 H+ + 2 e $ HzSe03 + HZO ClO; + 2 H+ + e $ CI@ + HzO I++ + 3 e $ l r ClO; + 2 H+ + 2 e e ClO; + HzO

N204 t 2 H + + 2 e = 2 H N O Z

[Cu(CN)2]- pt2' + 2 e $ PI

E', V ~

0.851 0.854 0.857 0.86 0.8865 0.867 0.878 0.920 0.934 0.951 0.954 0.957 0.959 0.983 0.987 0.991 1.00 1 .00 1.002 1.006 1.02 1.035 1.06 1.062 1.065 1.086 1.085 1.0873 1 .w9 1.118 1.120 1.147 1.151 1.152 1.156 1.189

Reaction P . V

2 10, + 12 H+ + 1 0 e e l2 6 H20 C103 +3H++2e$HC102+Hz0 MnOz +4H+ + 2 e $ Mn2+ + 2 HZO 02 +4H+ + 4 e 2 2 H Z 0 CrZ@- + 14 H+ + 6 e $ 2 C+ + 7 H20 O3 + HzO + 2 e $02 + 2 OH- n3+ + 2 e e n + NzH: + 3 H+ + 2 e $ 2 NH: CQ + H+ + e $ HCIOz [PdC!& + 2 e + [PdCI4l2- + 2 CI 2 HN02 + 4 H+ + 4 e$ NzO + 3 HzO P U ~ ~ ( O H ) ~ + 2 H+ + 2 e $ Pu(OH)~ HBrO+ H+ + 2 e $ Br- t H20 HCrO; + 7 H+ + 3 e $ C?+ + 4 H20 Clz(g) + 2 e $ CI- CIO; + 8H+ + 8 e $ CI- + 4 H20 ClO; + 8H+ + 7 e $ 1/2CIz + 4Hz0 Au3++2e$Au+ 2 NH30H+ + Hf t 2 e e NzH: + 2 Hz0 BrO;+6H++6e$Brr+3H20 2HIO+2H++2e$ Iz +2H20 Au(OH)~ + 3 Hi + 3 e s Au- + 3 H20 310; + 6 H + +6e$CI - + 3 H z 0 P a + 4 H- + 2 e $ P b + + 2 HzO CIO; + 6 H+ + 5 e 2 1/2 Clz + 3 H20 BrO; + 6H+ + 5 e 2 1/2 Br2 + 3 H20 HClO + H+ + 2 e 2 CI- + H20 HOZ + H+ + e $ Hz@ Au3+ + 3 e $ Au MnO; + 8 H+ + 5 e s Mn2+ + 4 Hz0 Mn3+ + e $ Mnz' HCIOz + 3 H+ + 4 e + CI- + 2 HzO HBrO + H+ + e $1/2 Br2(aq) + H20 2 NO + 2 Hi + 2 e $ NzO+ H20 Bi201 + 4 H+ + 2 e $ 2 BiO+ + 2 H20 HBrO + H+ + e $ 1/2 BrzV) + HzO

1.195 1.214 1.224 1.229 1.232 1.24 1.252 1.275 1.227 1.288 1.297 1.325 1.331 1.350 1.35827 1.389 1.39 1.401 1.42 1.423 1 .I39 1 .A5 1.451 1.455 1.47 1.482 1 .A82 1.495 1.498 1.507 1.5415 1.570 1.574 1.591 1.593 1.596

Reaction E", V Reaction Eo. V

Hsl06+H+ +2e=10, + 3 H z 0 Ce4+ + e e Ce3+ HClO + Hi + e $ 112 C12 + H20 HC1O2 + 3 Hi +3e: 112 CIS + 2 H20 HCIOl + 2 Hi + 2 e e HClO + H20 NiOz MnO;+4Ht+3e$MnOzt2H20

4 Hi + 2 e : Ni2+ + 2 HzO

PbOz-+ S q - + 4 Hi + 2 e e PbS04 + 2 H20 Au+ +e$Au -OH3' + H' + e $ Ce3+ + H20 N20 + 2 H+ + 2 e e N2 + HZO H20Z + 2 H+ + 2 e e 2 HzO

1.601 1.61 1.61 1 1.628 1.645 1.678 1.679 1.6913 1.692 1.715 1.766 1.776

Co3+ + e : C$+ (2 molN H2S04) A#+ + e e A g + ~ ~ 0 : - + 2 e $ 2 SO:- O H + e e O H O3 + 2 H+ + 2 e g O2 + HzO ad,- +2H' +2e$2HSO: F20 + 2 H+ + 4 e 2 H20 + 2 F- FeO-+8H++3e=Fe3++4H20 O(g)+2H+ +2e:H20 H2N202 + 2 H+ + 2 e e NP + 2 HZO F, + 2 e e 2 F- F2+2H+ + 2 e $ 2 H F

1.83 1.980 2.010 2.02 2.076 2.123 2.153 2.20 ~~

2.421 2.65 2.866 3.053

REDUCTION REACTIONS HAVING E" VALUES MORE NEGATIVE THAN THAT OF THE STANDARD HYDROGEN ELECTRODE

Reaction

2 H ' + 2 e e H z AgCN + e $ Ag + CN- 2 W03 +2H+ + 2 e $ W205 + HzO W205 + 2 H+ + 2 e e2 WOZ + HzO D' + e : 112 D2 AgzS + 2 H' + 2 e : Ag + H2S Fe3+ + 3 e $ F e Hg,12 + 2 e : 2 Hg + 2 I- 2 D + + 2 e $ D 2 TI(OH)3 + 2 e $ TlOH + 2 OH Tt0H3' + H' + e : Ti3' + H20 2 HzS03 + H+ + 2 e e HS20; + 2 HZO P(whlte) + 3 H+ + 3 e : PH3(g) 0; +HzO+2e=HO; +OH- 2 CU(OH)~ + 2 e = Cu20 + 2 OH + H20 WOs + 6 H+ + 6 e e W + 3 HzO P(red) + 3 H+ + 3 e : PH3(g) G d z + 2 Hi + 2 e e GeO + H20

E". V

-0.00000 -0.017 -0.029 -0.031 -0.0034 -0.0366 -0.037 -0.0405 -0.044 -0.05 -0.055 -0.056 -0.063 -0.076 -0.080 -0.090 -0.111 -0.118

Reaction

WO, +4H+ + 4 e $ W + 2 H20 Pbzt + 2 e $ Pb(Hg) Pb" + 2 e $ Pb CrO- + 4 H20 + 3 e $ Cr(OH)3 + 5 OH- Sn2- +2e$Sn In+ + e e In Oz + 2 H20 + 2 e + H2O2 + 20H- Agl + e: Ag + I- 2 NO; + 2 Hz0 + 4 e $ N20: + 40H- H~Ge03 + 4 H+ + 4 e S Ge + 3 H20 Co2 + 2 H' + 2 e $ HCOOH Mo3++3e=Mo 2 S q - + 4 H + + 2 e e S z 0 E +H20 CU(OH)Z + 2 e e Cu + 2 OH- CdSO, + 2 e $ Cd + SO:- '/(OH); + 4 H+ + 5 e $ V + 4 H20 P + e e V 2 + Ni2+ + 2 e g Ni

E", V

0 0

0

2

-0.119 -0.1205 -0.1262 -0.13 -0.1375 -0.14 -0.146 -0.15224 3 -0.18 -0.182 -0.199 -0.200 -0.22 -0.222 -0.246 -0.254

2

2 -0.255 -0.257 8

(Continued)

ELECTROCHEMICAL SERIES (Continued)

Reaction ED. V Reaction

PbCIz + 2 e $ Pb + 2 CI- H3P0.4 + 2 H+ + 2 e e H3P03 + HzO c d t + 2 e e C o PbErz + 2 e s Pb + 2 k- TI+ + e s TI(Hg) ~ ~ + + e e n 1h3+ + 3 e $ In TlOH + e e n + OH-

PbSO, + 2 e e Pb(Hg) + SCi- Cd2+ + 2 e e Cd(Hg) P b W 4 + 2 e e pt, + sG- CuzO + HzO+ 2 e $2 Cu + 2 OH- Eu3+ + e e Eu2+ Pblz + 2 e $ Pb + 2 I- Se:- + 3 H20 + 4 e $ Se + 60H- Ti3+ + e $ Ti* Se + 2 H+ + 2 e $ H,Se(aq) In2+ + e e In+ Cdz+ +Pe+Cd cP + e e C6+ 2 s + 2 e e s$- mzS0, + 2 e in3+ + 2 e $ In+ F$+ + Z e e F e H3P03 + 3 H+ + 3 e + P + 3 H Z 0 Bi203 + 3 HzO + 6 e $ 2 EI + 6 OH- NO; + HzO + e e NO + 2 0 H PbHPOb + 2 e $ Pb + HF'G- S + 2 e s S2- S + H20 + 2 e s HS- +OH- Ni@ + 2 H20 + 2 e + Ni(0Hk + 20H in3+ + e $ In2+ H 3 W 3 + 2 H' + 2 e $ H3PQ + HzO T i 0 2 + 4 H+ + 2 e e Ti2+ + 2 HzO H3P02 + H+ + e g P + 2 HzO

PbFz + 2 e e P b + 2 F -

TI + sQ-

-0.2675 -0.276 -0.28 -0.284 -0.3338 -0.336 -0.3382 -0.34 -0.3444 -0.3505 -0.3521 -0.3588 -0.360 -0.36 -0.365 -0.366 -0.368 -0.399 -0.40 -0.4030 -0.407 -0.42836 -0.4360 -0.443 -0.447 -0.454 -0.46 -0.46 -0.465 -0.47627 -0.478 -0.490 -0.49 -0.499 -0.502 -0.508

Sb+3H4 +3e$SbH3 HPbO; + HzO + 2 e $ Pb + 3 0 H nci + e e n + CI- Ga3+ + 3 e $ Ga Fe(0Hb + e $ Fe(0Hk +OH- TeO- + 3 HZO + 4 e 2 Te + 60H- 2SG$ +3H,0+4es%O?? +60H- PbO + H20 + 2 e s Pb +20H- ReO; + 4 H20 + 7 e $ Re + 8 OH- SbOi + H20 + 2 e e SW; + 2 OH- U4+ + e $ U3+ As+3Ht + 3 e e A s H 3 NbzO, + lOH+ + 10e$ 2 Nb+ 5 H20 TI& + e $TI + Err SbO; + 2 HzO + 3 e $ Sb + 40H- AsO; + 2 H20 + 3 e $ As + 40H- AgzS + 2 e $ 2Ag + Sz- AsO- + 2 Hz0 + 2 e + AsO; + 4 OH- NI(OH)~ + 2 e $ NI + 2 OH- Co(OHk + 2 e $ Co + 2 OH- H,SeO, + 4 H+ + 4 e $ Se + 3 H20 C Z + + 3 e e C r Taz05 + lOH+ + 10e $2Ta + 5 HzO ni + e en + I- Zn2+ + 2 e e Z n Zn2+ + 2 e $ Zn(Hg) Te+2H' +2e$HzTe ZnS04 .7Hz0 + 2 e $ Zn(Hg) + SC?- (Sat'd ZnS04) Cd(OH)z + 2 e e Cd(Hg) + 2 OH- 2 HzO + 2 e + HZ + 2 OH- 2 NO; + 2 HzO + 2 e $ Nz04 + 4 OH- H3B03 + 3 H+ + 3 e e B +3H;0 P + 3 H20 + 3 e e PH3(g) + 3 OH- HSnO; + H20 + 2 e $ Sn +30H- C12++2eeCr Se+ 2 e e se2-

8

n

5

E".V

0 -0.510 -0.537 -0.5568 -0.560 -0.56

-0.571 -0.580 -0.584 -0.59 +0.607 -0.608 -0.W -0.658

-0.68 -0.691 -0.71 -0.72 -0.73 -0.74 -0.744 -0.750 -0.752 -0.7618 -0.7628 -0.793 -0.7993 -0.809 -0.8277 -0.85 -0.8698 -0.87 -0.909 -0.913 -0.924

-0.57 8

2 2

2

-0.66 0

Reaction

Sb,- + H20 + 2 e $ S O - + 20H- Sn(OH): + 2 e + HSNO; + 3 OH- + Hz0 N@z + HzO + Hi + e $ Np(0Hh P q - + 2 H z 0 + 2 e = H P 6 , ~ + 3 0 H - Nb3+ + 3 e $ N b 2 S%- + 2 HzO + 2 e $ SzO:- + 4 OH- Te + 2 e $ Te2- v2+ + 2 e $ V Mnz+ + 2 e $ Mn Cao; + 2 H20 + 3 e $ Cr + 4 OH- ZnO; + 2 HzO + 2 e $ Zn + 4 OH- HzGaO; + HzO + 3 e $ Ga + 4 OH- HzBO; +5H20+8e$BH; + 8 0 H SiF2- + 4 e $ Si + 6 F- Ce'+ + 3 e $ CMHg) U q + + 4 H + + 6 e $ U + 2 H 2 0 ~Zrf0H)~ + 3 e $ Cr + 3 OH- HfO, + 4 H + + 4 e $ H f + 2 H 2 0 Z1oz +4H+ + 4 e $ Z r + 2 H 2 0 Mn(OH)z + 2 e $ Mn + 2 OH- &+ + 2 e $ Ba(Hg) W f + 2 e $ T i HPO;- + 2 Hz0 + 2 e $ HzPO; + OH- A13f + 3 e g N S O - + H20 + 4 e + Si + 6 0 H HPC$ + 2 HzO + 3 e $ P + 50H- Hfb ' + 2 H' + 4 e no2 + 4 H- + 4 e ern + 2 H20 Hz60, + H20 + 3 e e B + 4 OH- SP+ + 2 e $ Sr(Hg) U3' + 3 e $ U HzPO; + e + P + 2 0 H

+ 2 e g Be Np3+ + 3 e $ Np

HI + HzO

E', V

-0.93 -0.93 -0.962 -1.05 -1.099 -1.12 -1.143 -1.175 -1.185 -1.2 -1.215 -1.219 -1.24 -1.24 -1 -4373 -1.444 -1.48 -1.505 -1.553 -1.56 -1.570 -1.630 -1.65 -1 662 -1 -697 -1.71 -1.724 -1.789 -1.79 -1.793 -1.798 -1.82 -1.847 -1.856

Reaction

Th4+ +4e$Th PU3+ + 3 e $ PU AIF; + 3 e $ N + 6 F - SFl+ + 3 e $ Sc HI + 2 e $2 H- HzNO;+HzO+3e$AI+40H- ZrO(0Hk + Hz0 + 4 e $ Zr + 4 OH- Mg2++2e$Mg

Eu3+ + 3 e $ Eu Nd3++3e$Nd Th(OH)., + 4 e + Th + 4 OH Cgl+ +Be+& HfO(0Hk + HzO + 4 e + Hf + 4 OH La3++3e$La Be20;- + 3 Hz0 + 4 e $2 Be + 6 OH Mg(0Hk + 2 e $ Mg + 2 OH- Mgt + e $ Mg Na+ + e $ Na Caz+ + 2 e $ Ca Sr(0H)z + 2 e sZ+ + P e g % La(OH)3 + 3 e + La + 3 OH- Baz++2e+Ba Cs+ +e$Cs K + + e $ K Rb +e$Rb Ba(OHk + 2 e $ Ba + 2 OH- Ca(0Hk + 2 e + Ca + 2 OH- IJ+ + e $ h 3 N2 + 2 H+ + 2 e $ 2 NH3 Ed+ +2e$Eu Ca++e$Ca Sr++e$Sr

Y3++3e$Y

Sr + 2 OH

E', V ~

-1.899 -2.031 -2.069 -2.077 -2.23 -2.33 -2.36 -2.372 -2.372 -2.407 -2.431 - 2.48 -2.483 -2.50 -2.522 -2.63

-2.70 -2.71

-2.690 0

-2.868 4 -2.88 0

2

CI,

-3.09 G)

-2.89

-2.912 -2.92 -2.931 -2.98 -2.99 -3.02 -3.0401 3 -3.395 -3.80 -4.10

-2.90 8 3


EMF SERIES FOR METALS

Electrode Reaction

Standard Potential at 25'C (77T), Volts

versus SHE

Au31 + .W - Au Pd2+ + Pe- + Pd Hg2+ + 2e- - Hg

.................................................................................................

.................................................................................................

................................................................................................. Ag+ + e- + Ag . . , . , . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . , . , . . , . . , . , , . , . . , . , . . . . , . , Hg :+ + 2e- + 2 Hg. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . , , . . Cu' + e- +Cu ................................................................................................. Cu2+ + 2e- + Cu 2 Hi + 2e- + H2

Pb2+ t 2e- + Pb Sn2 + 2e- - Sn Ni2' + 2e- + Ni Co2+ + 2e- + Ni

in3+ + %- + In .................................................................................................. Cd2+ + Pe- + Cd ................................................................................................... Fez+ + 2e- + Fe Ga3+ + 3e- + Ga ........................................................................................ CP+ + 3e- + Cr ..................................................................................................

....................................... , , . , , , , , . . . , , . . . . . . . . . . . . . . . . . . . . .

....................................... , , , . . , . , . . . . . , . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . , . . , . . . . . . . . . . . . . . . , . , . , , . , . , , , , , , , , , , , , , , , , , , , , , , , , , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . , , . , . . ,

..................................................................................................

.. . . , . . , . , . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . TI+ + e- + TI ................................................................

...................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

, , . , , , , . , , . , . . . . . . , . . . . . . . . . . . . . . . .

Mn2+ + Pe- + Mn .................................................................................................. Ze+ +&- + Zr Ti2+ + 2e- + Ti

HVt + 4e- - Hf u3+ + 3e- + u Be2' + 2e- + Be ...................... Mg2+ + 2e- + Mg ........................................................................................ Na+ + e- + Na CaZ+ + 28- + Ca K + + e - - K .................................................................................................. Lit + e- + Li ..................................................................................................

. . , . , , . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . , . . , . , , . . . . , . , , . . . , , . , . . , . , . ...............................................................

~ 1 3 - + 3e- - AI .................................................................................................. ................................................................................................... ......................

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................................................................................................

1.50 0.987 0.854 0.800 0.789 0.521 0.337

(Reference) 0.000

-0.126 -0,136 -0.250 -0,277 -0.336 -0.342 -0.403 -0.440 -0.53 -0.74 -0.91 -0.763 -1.18 -1.53 -1.63 -1.66 -1.70 -1.80 -1.85 -2.37 -2.71 -2.87 -2.93 -3.05

Source: Metals Handbook, 9th ed., Voi. 13, p. 20, ASM, 1987. Reprinted by permission of ASM International@, Materials Park, OH 44073-0002.


TYPICAL POTENTIAL-pH (POURBAIX) DIAGRAM IRON IN WATER AT 25°C

PH

IONIC SPECIES ARE AT ACTIVITIES OF 1V AND 106

Source: M. Pourbaix, Atlas of Electrochemical Equlibria in Aqueous Solutions, NACE, p. 313, 1974.


STANDARD ENVIRONMENTS FOR ENVIRONMENTAL CRACKING TESTS

Temperature Standard Environment "C Materials

NACE TM0177

ASTM G 35

ASTM G 36

ASTM G 37

ASTM G 41

ASTM G 44, G 47

ASTM G 103

ASTM G 123

IS0 9591

is0 9591

IS0 15324

5.0% NaCl + 0.5% Acetic acid, saturated with HzS (1 atm.)

Polythionic acid solution 22-25

21-27

45% MgCIz (boiling) 154-156

Mattsson's Solution. pH 7.2 18-24 (CuS04 + (NH&S04 + NHIOH)

NaCl or other salts or synthetic seawater

3.5% NaCl (at. immersion) 26-28

230-450

6% NaCl Boiling

25% NaCI, pH 1.5 Boiling with phosphoric acid

3.5% NaCI, 25 (alt.immersion)

2.0% NaCl

pH = 3.0 0.5% NazCr04

25

0.1 M NaCl 20-26 Dripped on 300°C specimen

All metals

Stainless steels Related nickel-chromium- iron alloys

Stainless steels Related alloys

Copper-zinc base alloys

All metals

Aluminum alloys Ferrous alloys

A-Zn-Mg alloys

Stainless steels

Aluminum alloys

Aluminum allow

Stainless steels Nickel based alloys

SPECIMEN TYPES USED IN ENVIRONMENTAL CRACKING TESTS

Pmduet Form Used to Determine Loading ylecimen System Type Standard Sheet Bar plate Tube Wim TI om lG- d d d t la

Constant Load

Constant Strain

Slow Strain Rate

Sustained-Loading Crack-Growth

Bent Beam Notched beam Direct tension

U-bend CUP C-ring Bent beam Direct tension Tuning fork Weld bead Rwgh ground Haifpin

Round tensile Tube

DCB

ASTM G 49

ASTMG30

ASTM G 38 ASTM G 39 ASTM G 49

-

- -

x x x x x x X

X X X

x x X x x x x

x x x x x

X X X

x x x X

x x

X X X X X x x X

x x X X X X X X X

X X

X

X

0 0 %

X 8 X

X 5 2

Tf time to failure. at,, threshold stress. Klscc threshold stress intensity. daldt crack growth rate. I1cc index of susceptibility.

2 0

._

Source: See IS0 7539, Palts 2 through 8 and NACE TM0177


TYPICAL HIGH TEMPERATURE/HIGH PRESSURE TEST CONDITIONS

NO. Application Environment Tamp, C Pmssum, MPa (bar)

8 9

10 11 12 13

Nuclear Power

Fluidized Bed Combustion

Deep Sea Oil and Gas

Aerospace Propulsion

Petroleum Refining Compressed Natural

Gas Storage Ammonia Storage Thermodynamic Power

Exhaust Gas Processing Natural Gas Pipeline Geothermal Power Steam Boiler

Production

Generation

high-purity water/steam/Hz air, gas, coal

seawater brine, H2S. COz, S

hydrogen oxygen Hz, HzS, hydrocarbons methane w/trace H2S

NH3. Hz0 NH3, H20

Hz. Nz, CO, COz CH4 wArace H~S/C02/02 brine, steam, HzS waterkteam

280 to 500

600 to 750

0 to 70' 20 to 250

-200 to 900 -200 to 480 350 to 650

0 to 100

0 to 70 100 to 650

(70 560 5370 5300

517 (170)

1 (10)

< 5 (50) 5130 (1300)

0.1 to 67 (1 to 670) 58 (80) 510 (100) (8 (80)

5 4 (40) 1.5 to 11 (15 to 110)

535 (350) (13 (130) 517 (170) 59 (90)

*Pipeline surface temperature.

Source: Manual 20, p. 106, ASTM, 1995. Reprinted, with permission, copyright ASTM.


PLANNED INTERVAL CORROSION TEST Used to Evaluate Effect of Time on Corrosion Rate and to Determine if the Time Effect is Due to Changes in Environment Corrosiveness or in Metal Corrodibility

0 1 Time t t t l

Identical specimens all placed in the same corrosive fluid. Imposed conditions of the test kept constant for entire time t + I. Letters A,, A1, At+, , B, repre- sent corrosion damage experlenced by each test specimen. A? is calculated by subtracting At from At + 1.

Occurrences During Corrosion Test Criteria

unchanged A1 = B Liquid corrosiveness decreased B < A,

increased A, < B

unchanged A2 = B Metal corrodibility decreased A2 < B

increased B < A2

Liquid Corrosiveness

Combinations of Situations Metal Corrodibility Criterla

1. unchanged unchanged A, = A2 = B 2. unchanged decreased A2 < A1 = B 3. unchanged increased A, = B < A2 4. decreased unchanged A2 = 8 < A, 5. decreased decreased A2 < B < Al 6. decreased increased A, 5 B < A2 7. increased unchanged A, < A2 = B 8. increased decreased A, < B > A2 9. increased increased A, < B < A2

Example

Interval, Days Apparent

wt. Loss, Penetration, Corrosion mg mlls Rate, mlldyr.

A1 ............ 0-1 & ............ 0-3 &+I ...... 0-4 B .............. 3-4 A2 ............ calc. 3-4

1080 1430 1460

70 30

1.69 2.24 2.29 0.1 1 0.05

620 270 210

40 18

A2 < B < A, 0.05< 0.11 < 1.69

Therefore, liquid markedly decreased in corrosiveness during test, and formation of partially protective scale on the steel was indicated.

Source: A. Wachtner and R. S. Treseder, "Corrosion Testing-Evaluation of Metals for Pro- cess Equipment," Chemical hgineering Progress, Voi. 43, p. 318, 1947. Reprinted by permission of American institute of Chemical Engineers.


CORROSION RATE CONVERSION FACTORS

Mildyear (mpy) = C x :2;)2tfi: x K

Millimetredyear (mm/y) = 0.0254 mpy

C Factors Weight Loss h a Hour Day Waek Month Year

mg cmZ 437 18.2 2.59 0.598 0.0498

m2 0.0437 1.82 x 1 0 - ~ 2.59 x 5.98 x 4.98 x

ft2 0.470 0.0196 2.79 x 6.44 x 5.36 x

drn2 4.37 0.182 0.0259 5.98 10-3 4.98 10-4

in2 67.7 2.82 0.402 0.0927 7.72 10-3

g om2 437 x 103 182 x 102 2590 598 49.8 dm2 4370 182 25.9 5.98 0.498

inz 677 x 102 2820 402 92.7 7.72 n2 470 19.6 2.79 0.644 0.0536

m2 43.7 1 .82 0.259 0.0598 4.98 10-3

ib cm2 198x lo8 625x 104 118x lo4 271 x lo3 2 2 6 x 102 dm2 198x lo4 625x 102 ll8x 10' 2710 226 rn2 198x loz 825 118 27.1 2.26 in2 307x lo5 128x 104 182x lo3 420x lo2 3500 R2 213 x lo3 8880 1270 292 24.3

EXAMPLE A 5.0 square inch specimen of copper has a weight loss of 218 mg in a 40 hour corrosion test.

218. mpy = 67.7 x - 5,0 4o x 0.68 = 65

mmly = 0.0254 x 65 = 1.65

K is a density factor. K = 1,000 for carbon steel. K factors for other alloys are given on the next page.

Source: Courtesy Aaron Wachter.


UNS

A91 100 A93003 A95052 A96061 A97075 c11000 c22000 C23000 C26000 C27000 C28000 C44300 C46500 C51000 C52400 C61300 '261400 '33000 C65500 C67500 C68700 C70600 C71500 C75200 C83600 C86500 C90500 c92200 C95700 C95800 F10006 F20000 F32800 F41002 F43006 F47003 GI0200 G41300 J91150 J91151 J91540 J92600 J92800 J92900 J94204 J95150 K11597 K81340 L51120 M11311 NO2200 NO4400 NO5500 NO6002

DENSITIES OF COMMON ALLOYS (K = ratio of carbon steel density to that of alloy)

Density CommonName g k m 3 K

Al 1100 2.72 2.89 Ai 3003 2.74 2.67 A15052 2.68 2.93 A6061 2.70 2.91 A17075 2.80 2.81 ETP Copper 8.94 0.88 Commercial Bronze 8.89 0.88 Red Brass 8.75 0.90 Cartridge Brass 8.53 0.92 Yellow Brass 8.39 0.94 Muntz Metal 8.39 0.94 Admiralty brass. As 8.52 0.92 Naval Brass. As 8.41 0.93 Phosphor Bronze A 8.86 0.89 Phosphor Bronze D 8.78 0.90 Aluminum Bronze. 7% 7.89 1.00 Aluminum Bronze D 7.78 1.01 Ni-AI Bronze 7.58 1.04 High-Silicon Bronze 8.52 0.92 Manganese Bronze A 8.36 0.94 Aluminum Brass, As 8.33 0.94 9-10 Copper-Nickel 8.94 0.88 70-30 Copper-Nickel 8.94 0.88 Nickel Silver 8.73 0.90 Ounce Metal 8.80 0.89 Manganese Bronze 8.3 0.95 Gun Metal 8.72 0.90 M Bronze 8.64 0.91 Cast Mn-Ni-Al Bronze 7.53 1.04 Cast NI-AI Bronze 7.64 1.03 Gray Cast Iron 7.20 1.09 Malleable Cast Iron 7.27 1.08 Ductile Iron 7.1 1.11

Ductile Ni-Resist, D5 7.68 1.02 Duriron 7.0 1.12 1020 Carbon Steel 7.86 1 .OO 4130 Steel 7.86 1.00 CA-15 Cast SS 7.61 1.03 CA-15M Cast SS 7.61 1.03 CA-6NM Cast SS 7.7 1.02 CF-8 Cast SS 7.75 1.01 CF-3MN Cast SS 7.75 1.01 CF-8M Cast SS 7.75 1.01 HK-40 Cast SS 7.75 1.01 CN-7M Cast SS 8.00 0.98 1.250-0.5Mo Steel 7.85 1.00 9Ni Steel 7.86 1.00 Chemical Lead 11.3 0.70 Mg AZ31B 1.77 4.44 Nickel 200 8.89 0.88

K-500 Alloy 8.44 0.93 X Alloy 8.23 0.96

Ni-Resist Type 2 7.3 1.08

400 Alloy 8.80 0.89

Density UNS CommonName g/cm3 K

NO6007 G Alloy NO6022 C-22 Alloy NO6030 G-30 Alloy NO6455 C-4 Alloy NO6600 600 Alloy NO6601 601 Alloy N06625 625 Alloy NO6985 G-3 Alloy NO7001 Waspaloy NO7041 Rene 41 NO7718 718Alloy NO7750 X-750 Alloy NO8020 20Cb-3 NO8024 20Mo-4 NO8026 20Mo-6 NO8028 Sanicro 28 NO8366 AL-6X NO8800 800 Alloy NO8625 825 Alloy NO8904 904L Alloy NO8925 25-6M0 NO9925 925 Alloy N10003 N Alloy N10004 W Alloy N10276 C-276 Alloy N10665 8-2 Alloy R03600 Molybdenum R04210 Niobium R05200 Tantalum R50250 Titanium, Gr 1 R50400 Titanium. Gr 2 R53400 Titanium. Gr 12 R56400 Titanium, Gr 5 R60702 Zr702 s20100 201 ss s20200 2025s 530400 30455 530403 304LSS 530900 30955 531000 31055 531254 254 SMO 531500 3RE60 531600 316SS 531603 316LSS 531700 317SS 532100 321 SS 532550 Fermium 255 532950 7 Mo Plus 534700 34755 541000 41055 j43000 430SS 544600 446SS 350100 5Cr-0.5Mo Steel 350400 9Cr-1 Mo Steel

8.34 0.94 8.69 0.90 8.22 0.96 8.64 0.91 8.47 0.93 8.11 0.97 8.44 0.93 8.30 0.95 8.19 0.96 8.25 0.95 8.19 0.96 8.28 0.95 8.08 0.97 8.11 0.97 8.13 0.97 8.0 0.98 8.0 0.98 7.94 0.99 8.14 0.97 8.0 0.98 8.1 0.97 8.05 0.98 8.79 0.89 9.03 0.87 8.89 0.86 9.22 0.85 10.22 0.77 8.57 0.92 16.60 0.47 4.54 1.73 4.54 1.73 4.52 1.74 4.43 1.77 6.53 1.20 7.94 0.99 7.94 0.99 7.94 0.99 7.94 0.99 7.98 0.98 7.98 0.98 8.0 0.98 7.75 1.01 7.98 0.98 7.98 0.98 7.98 0.98 7.94 0.99 7.81 1.01 7.75 1.01 8.03 0.98 7.70 1.02 7.72 1.02 7.65 1.03 7.82 1.01 7.67 1.02


DENSITY OF MATERIALS

Density Density Density Density Material (g/cm3) ( lb/h3) Material (g/cm3) (lb/in.3)

Indium Osmium Platinum Rhenium Tungsten Gold Uranium Tungsten carbide Tantalum Tantalum carbide

Hafnium Ruthenium Rhodium Palladium Thallium Thorium Lead Silver Molybdenum Bismuth Thulium Cast high leaded

tin bronze Nickel-moly

(Hastelloy 5-2) Copper Nickel Copper nickel

Cobalt Nickel silver Brass

(61.5Cu-3Pb-35.5Zn) Bronze

(57Cu, 40.73, 3Pb) Cadmium Niobium (Columbium) Nickel chromium

cobalt alloy Nickel-chromium

(Inconel 718) Copper zinc alloy Maraging steel Austenitic stainless steel Iron-nickel (Invar) Iron

Ir4

(MCu-14Ni-22Zn)

22.65 22.61 21.45 21.00 19.40 19.30 19.07 17.20 16.60

14.53 13.10 12.45 12.41 12.02 11.85 11.50 11 3 4 10.49 10.20 9.80 9.31

9.29

9.20 8.96 8.90

8.85 8.85 8.70

8.70

8.70 8.65 8.57

8.21

8.20 8.19 8.02 8.00 8.00 7.87

0.82 0.82 0.77 0.76 0.70 0.70 0.69 0.62 0.60

0.52 0.47 0.45 0.45 0.43 0.43 0.42 0.41 0.38 0.37 0.35 0.34

0.34

0.33 0.32 0.32

0.32 0.32 0.31

0.31

0.31 0.31 0.31

0.30

0.30 0.30 0.29 0.29 0.29 0.28

Nickel iron superalloy Chromium steel Nonresulfurized carbon steel Stainless steel (17Cr-4Ni) Hot work tool steel Aluminum bronze Babbitt Samarium Manganese

Indium Niobium nitride Tin Cerium dioxide Austempered ductile iron Pewter (Sn, Sb, Cu) Chromium Zinc Neodymium Praseodymium Cerium Chromium carbide

Antimony

Zirconium Lanthanum Vanadium

Nickel alumlnide (NiAi) Gallium Zirconia (partially stabilized)

Germanium

Titanium nitride Titanium carbide Titanium diboride

Titanium

Ti-6Ai-4V Titanium dioxide Aluminum oxide Spinel (Mg0.Ai303) Aluminum nitride Sialon

7.86 7.83 7.83 7.81 7.75 7.64 7.50 7.49 7.43

7.31 7.30 7.30 7.28 7.20 7.20 7.19 7.13 7.00 6.77 6.77 6.70

6.65

6.49 6.15 6.11

6.05 5.91 5.70

5.32

5.29 4.94 4.52

4.51

4.50 4.25 3.98 3.57 3.26 3.20

0.28 0.28 0.28 0.28 0.28 0.28 0.27 0.27 0.27

0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.26 0.25 0.24 0.24 0.24

0.24

0.23 0.22 0.22

0.22 0.21 0.21

0.19

0.19 0.18 0.16

0.16

0.16 0.15 0.14 0.13 0.12 0.12

(Continued)


DENSITY OF MATERIALS (Continued)

Density Density Density Density Material (g/cm3) (Ib/h3) Material (g/cms) ( l b / i~~ .~ )

Silicon nitride Mullite

Silicon carbide Hydroxyapattte Aluminum carbide Wollastonite Aluminum copper alloy Aluminum zinc alloy Aluminum Cordierite E-glass fiber Pyrex glass Boron carbide Boron Silicon PTFE

Graphite

Boron nitride Sulfur Unsaturated polyester Poiyimide thermoset Phenolic resin Beryllium

Phosphorus Carbon fiber

(3Al2 0 3 -2Si02)

(polyietrafluoroethyiene)

3.19

3.16 3.10 3.10 2.99 2.90 2.84 2.78 2.70 2.65 2.62 2.52 2.52 2.40 2.33

2.30 2.26

2.25 2.07 2.00 2.00 1.99 1.85

1.83 1.74

0.12

0.1 I 0.11 0.00 0.11 0.10 0.10 0.10 0.10 0.10 0.10 0.09 0.09 0.09 0.08

0.08 0.08

0.08 0.07 0.07 0.07 0.07 0.07

0.07 0.06

Magnesium PPS

Nylon 6 Acetai resin Epoxy resin C a I c i u m Rubidium Polycarbonate Aramid fiber Aromatic polyamide Bismaleimide resin Silicone PEEK (polyetheretherketone) Cellulose acetate Human Bone

Polyurethane ABS (acrylonitrile

Polysuifone Acrylic Polypropylene Sodium PE (polyethylene) UHMWPE (ultrahigh

Potassium Lithium

(polyphenylene sulfide)

butadiene styrene)

molecular weight PE)

1.74 0.06

1.67 0.06 1.64 0.06 1.57 0.06 1.56 0.06 1.55 0.06 1.53 0.06 1.53 0.06 1.45 0.05 1.44 0.05 1.36 0.05 1.35 0.05 1.32 0.05 1.30 0.05 1.30 0.05

1.27 0.05

1.26 0.05 1.24 0.04 1.19 0.04 1.05 0.04 0.97 0.04 0.95 0.03

0.93 0.03 0.86 0.03 0.53 0.19

Source: GEM 2001, p. 35, ASM, 2000. Reprinted by permission of ASM international@, Materials Park, OH 44073-0002.

EQUIVALENT WEIGHT VALUES FOR METALS AND ALLOYS

Elemenis ~

Common wIConstant Variable Designation UNS Valence Valence

Aluminum Albvs A A l l W AA2024 AA2219 m o o 3 moo4 AA5005 AA5050 AA5052 AA5083 AA5086 AA5154 AA5454 AA5456 AA6061 AA6070

AA6101 AA7072 AA7075

A91100 A92024 A92219 A93003 A93004 A95005 A95050 A95052 A95083 A95086 A95154 A95454 A95456 A96061 A96070

A96161 A97072 A97075

A47079 A97079

AA7178 A97178

copper Alloys CDAllO C l l w O CDA220 C22wO CDA230 C23000

Av3 Au3.MgQ C d l All3 Cull All3 Md2 Av3,Mg/2 M d 2 Au3, Msn Av3, MSn w3. MSn Al3. Mg12 Av3, Mg/2 Au3, Msn M. MSn AV3. Mg/2 Au3. Mg/2 Au3, MSn, w 4 Au3 Av3. w2 All3. Zd2, C d l Mg/2 Au3, M2. MSn Av3.znl2, C d l MQQ

cull Z d 2 Cull Zd2 C d l

Lowest second mi FwM

0

3

Equivalent Variabk Equivalem Element/ Equivalent Element/ Equivalent W i M Weigm Valence weimt Vaknoe Weight B

% $ G!

8.99 9.38 CUE 9.32 9.51 Cd2 9.42 9.07 Md4 9.03 Mn7 8.98

Mn7 9.00 9.09 Mnl4 9.06 9.01

9.05 9.09 9.09 9.08 9.06 9.11 9.01 8.98

9.03 0,

8.99 9.06 9.58

9.37

9.71

63.55 58.07 55.65

Cd2 9.55

cu/2 9.68

Cu/2 31.77 Cu/2 31.86 Cu/2 31.91

Lowest Third Fourlb

common Designation UNS

CDA260 C26OOO CDA280 C28000 CDA444 C44300 CDA687 -700 CDA608 C60800 CDA5lO C51000 CDA524 ‘252400 CDA655 C65500 CDA706 C70600 CDA715 C71500 CDA752 C752W

Stainless Steels 304 s30400 321 s32100 309 530900 31 0 s31000 31 6 s31600 317 531700 41 0 541000 430 S43000 446 s446w 20CEW NO8020

Nickel AlloF 200 NO2200 400 N04400 600 N06600 800 NO8800 825 NO8825

B NlOOOl C-22b N06022

Elements wlconstant

Valence Variable Equivalent Valence Weight

Zd2 Zd2 w 2 w 2 . tw3 Au3

Sif4 Ni/2 Nd2 Ni. zrd2

Ni2 Nil2 Nd2 N i Nd2 Nii2

N i

Nil2 Nil2 Nd2 Nil2

Nil2 Nd2

Cull 49.51 Cull 46.44

Cull, Sd2 50.42 Cull 48.03 Cull 47.114

Cull. Sn/2 63.32 Cull. Sd2 63.10

C d l 50.21 C d l 56.92 Cull 46.69 Cull 46.38

Fd2. Crf3 25.12 F&, Crf3 25.13 F&,Cr/3 24.62 Fd2. Crl3 24.44

F&. Crf3. Mo13 25.50 Fd2, Cr/3. MOB 25.26

F a . Crf3 25.94 Fd2. Crf3 25.30 F&. Crl3 24.22 Fd2. Crf3. 23.98

Mol3, Cull

N i i 29.36 cu l l 35.82

Fd2. Crf3 26.41 Fd2. Crf3 25.10 Fd2. CrD. 25.52 Md3. Cull

Mo/3,F& 30.05 Fd2, Crl3, 26.04 Md3. W14

Variable Equivalent Valance Weight

Cd2 32.04 Cul2 32.11

CUll,sn/4 50.00 Cd2 30.29 Cul2 27.76

Cd l .Sd4 60.11 Cull, Sn/4 57.04

Cd2 28.51 Cd2 31.51 Cul2 30.98 Cu/2 31.46

F&.Cr/3 18.53 Fd3. Crf3 19.08 Fd3, Cr/3 19.24 Fd3, Cr/3 19.73

F a . Crf3. Mof4 25.33 F&. Crf3. Mof4 25.03

Fd3,Cr/3 18.45 F a , Crl3 18.38 Fd3. Crf3 18.28 F&.Cr/3, 23.83

Mo14. Cull

Nil3 19.57 Cd2 30.12

Fd3.Cr/3 25.44 Fd3. Crf3 20.76 F a . Crf3, 25.32 MOf4, C d l

Md4, Fd2 27.50 F a , Crf3. 25.12 Mof4. W14

Element/ Equivalent Element/ Equivalent Valence Weight Valence Weight

Cul2.Sd4 32.W

Cd2.Sd4 31.66 Cd2.Sd4 31.55

Fel3. Crf6 15.72 F a . Crl6 15.78 Fd3. Cr16 15.33 F a : Crl6 15.36

Fd3. Crl6. Ma16 19.14 F a . Crl6. M d 6 19.15

F a . Crf6 16.28 F a . Crf6 15.58 F a : Crf6 14.46 Fd3. Crf3, 18.88

Mof6. Cd2

F a . Crl6 20.73 F a , Crl6 16.59 Fd3, Crf3, 21.70 Md6. Cd2

Mo16. Fd2 23.52 F a . CrB. 23.28 Md6, Wf6

Fd3, Crf6, Md6 16.111 Fd3, Crf6. Md6 15.82

Fd3, Crf6. 15.50 Mo16, Cd2

F a . Crf6. 17.10 Mo16. Cul2

Md6, Fel3 23.23 Fd3, Crl6. 17.88 Md6, W16

(Continued)

EQUIVALENT WEIGHT VALUES FOR METALS AND ALLOYS (Continued ) A A

Fourlh 0

0

Lowest Second Third Elements

Variable Equivalent Element/ Equivalent Element/ Equivalent 0 Common wlConstant Variable Equivalent

n n

5

Designation UNS Valence Vale- Weight Valance Weight Valence Weight Valence Weight

C-276 N10276 Nit2 Fet2. Crt3, 27.09 Crt3, Mot4 25.90 Fd2. Crt3. 23.63 Fel3, Crt6, 19.14

G N06W7 Ni2 (1) 25.46 (2) 22.22 (3) 22.04 (4) 17.03 Carbon Steel Fd2 27.92 Fd3 18.62

$

2 2

Mot3. W14 Mo16, Wt6 Md6, Wt6

2 (1) = Fd2, Crt3, Mot3. Cd l , Nbl4, Md2 (2) = Fd2, Crl3. Mo14. Cd2. Nbt5, Md2

(3) = Fet3, Crt3, MoI6, Cd2. Nbl5. Md2 (4) = Fd3. Cr16, Mot6, Cd2, Nb15, Md4

Other Mews Mg MI4142 Mgt2 12.15 Mo R0360O Mot3 31.98 Mo14 23.98 Mot6 15.99

Ta R05210 Tat5 36.19 Sn L13002 Sd2 59.34 Sd4 29.67 Ti R50400 Tit2 23.95 Ti3 15.97 Tit4 11.98 Zn z19001 Zd2 32.68 zr R60701 Zrt4 22.80 Pb L50045 Pb/2 103.59 Pbl4 51.80

Ag PO7016 Ad1 107.87 Ad2 53.93 GI

aFIegistered trademark Carpenter Technology. bRegistered trademark Haynes International. Note 1 : Alloying elements at concentrations below 1 % by mass were not included in the calculation, for example, they were considered part of the basis metal. Note 2: Midrange values were assumed for concentrations of alloying elements. Note 3: Only consistent valence groupings were used. Note 4: Equation 4 in ASTM G 102 was used to make these calculations.

Source: ASTM, G 102 (2000 Edition). Reprinted, with permission, copyright ASTM

CORROSION TESTING 11 1

where

CORROSION RATE CALCULATION FROM MASS LOSS

Corrosion rate = A W T (A x T x D)

K = a constant (see below), T = time of exposure in hours to the nearest 0.01 h, A= area in cm2 to the nearest 0.01 cm2, W = mass loss in g. to nearest 1 mg (corrected for any loss during cleaning (see 9.4)), and D = density in glcm3,

Many different units are used to express corrosion rates. Using the above units for T, A, W, and D , the corrosion rate can be calculated in a variety of units with the following appropriate value of K:

Constant ( K ) in Corrosion Rate Equation

345 x 106

2.87 x lo2

Conosion Rate Units Desired

miis per year (mpy) inches per year (ipy) 345 103 inches per month (ipm)

millimetres per year (mmly) micrometres per year (&My) picometres per second (pmls)

8.76 104 8.76 107 2.78 x lo6

grams per square metre per 1.00 x 104 x P hour (g/m2 .h)

milligrams per square decimetre per day (mdd)

micrograms per square metre per second (pglmz .s)

2.40 x lo6 x P

2.78 x lo6 x P

aDensity is not needed to calculate the corrosion rate in these units. The density in the constant K cancels out the density in the corrosion rate equation.

Source: ASTM, G 1 (2000 Edition). Reprinted, with permission, copyright ASTM.

11 2 CORROSION TESTING

VALUES OF CONSTANTS FOR USE IN FARADAY'S EQUATION

Calculation of Corrosion Rate-Faraday's Law can be used to calculate the corrosion rate, either in terms of penetration rate (CR) or mass loss rate (MR)

CR=Ki k E W

MR = K2 i,,, EW

where CR is given in mmlyr, i,, in $Afcm2, Ki = 3.27 x mm gl&Acm yr, p =density in g/cm3, MR = g/m2d, and K2 = 8.954 x g cm2/rrA m2 d. EW = Eouivaient weiaht

Other values for KI and K2 for different unit s stems are given in the following table: Aate

A

Penetration Rate Unit (CR) lcm Unit p unit Ki Units of Kls

mpy @hn2 g/cm3 0.1288 mpy gl&A cm mm/yF ,Winzb kg/m3b 327.2 mm ke/A m y mWyP &cm2 g/cm3 3.27 10-3 mm e/$A cm y

B

Mass Loss Rate unit i S M unit Kz Units of K2.

g/m2db N m Z b 0.8953 g/Ad mg/dm2d (mdd) wAfcm2 0.0895 mg crn2/wA dm2 d mg/dm2d (mdd) NmZb 8.953 10-3 mg m2/A dm2 d

aEW is assumed to be dimensionless.

%I unit.

Source: ASTM, G 102 (2000 Edition). Reprinted, with permission, copyright ASTM

Documents

Corrosion 1