alloys for corrosive environments nickel

7/26/2019 Alloys for Corrosive Environments Nickel

1/6

NICKEL

Alloys for

Corrosive

Environments

Awide range

of

nickel-base alloys

Copper,

molybdenum, and tungstenall increase

the

inherent

corrosionresistance ofnickel. In addi-

tion, mo y enum and tungsten are significant

in highly aggressive environments, strengthening agents, dueto their largeatomic sizes.

The

compositions of a fewnickel alloys are given

____________________________________________ in

Table

1.

These

are all wrought alloys, available

Rcnil B

Rebak*

in the formof plates, sheets, bars,pipes,tubes, forg-

P 1

~ ings, and

wires.

u~ roo ~

The

role of chromium is the

same

as that in the

Haynes

International Inc. stainless steels:

it

enhances the formation of pas-

Kokomo,Indiana sive surface films, in the

presence

of oxygen. These

passive

films impede

the

corrosion process.

Iron,

if added to the

nickel alloys,

also

affects

passiva

-

ickel-base

alloys provide outstanding tion. Silicon is

beneficial

at

high

corrosionpoten-

resistance

to specific chemicals, and tials,

where chromium-rich

passivefilms cannot be

some

are extremelyversatile and

able maintained.

It offers

extended protection through

-

to handle complex

process

andwaste the

formation

of protective (silicon-rich)oxides.

streams. In particular, the versatile

alloys

are much

less subject than stainless

s~.eels

ostresscorrosion Nickel

alloy metallurgy

cracking

pitting, andcrevice attack inhot chloride-

Most

of the corrosion-resistant nickel alloyshave

b e a r i n g s o l u t i o n s . A l s o , nickelalloys are among the a single-phaseatomic structure. In

common

with

fewmaterials able towithstand

hot

hydrofluoric the austenitic stainlesssteels, this is face-centered

acid, a chemical

that

is

very

corrosive to the reac- cubic. To optimize performance, designers of the

tive

metals titanium, zirconium,

niobium,

and nickel alloys

have

taken advantageof the fact

that

tantalum).

greater quantities

of elements such as chromium

The aim of this article is to describe the general and molybdenumare soluble in this face-centered

characteristicsof nickel-base alloysand to examine cubicstructure at temperatures in excess of 1000C

the effects of different

aggressive

environmentson (1830F) than at lower temperatures. Furthermore,

the corrosion behaviorof these alloys, added elements can

be

retainedwithin this phase

if thematerialsare water-quenched from the high

temperatures.

Therefore,

such alloys are

solution

a n n e a l e d todissolve anyunwantedsecond phases,

and water quenched to freeze-in thehigh-tem-

perature structure.

Second

phases arepossible, if they are subjected

to elevated

temperature

excursions, for example

during

welding. The

kinetics of second-phasefor-

Table

1

Nominal

compositions

of

nickel alloys

Nickel

alloy

t y p e s

The nickel alloys

canbe

categorized

according

to the

main alloying

elements, as follows:

Nickel: primarily forcaustic solutions.

Nickel-copper: primarily for

mild,

reducing

solutions,

especially

hydrofluoric a c i d .

Nickel molybdenum: primarily for strong,

reducingmedia.

Nickel-iron-chromium:

primarily for oxidizing

solutions.

Nickel-chromium-silicon:

primarily

for

super-

oxidizing

media.

Nickel-chromium-molybdenum:versatile

alloys

for all

environments.

The

terms reducing and

oxidizing

refer to

the nature of the reaction at cathodic sites

during

corrosion. Reducing solutions such as hydrochloric

acid

generally

induce

hydrogen evolutionat

ca

-

thodic

sites. Oxidizing

solutions such as nitric acid

induce

cathodic reactions

with higher

potentials.

*Merliber

ofASMInternational

Group

Alloy

Ni

Cu

Mo

Fe

Cr

Others

Ni

200 99.5

Ni-Cu

400 67

31.5

1 .2

Ni-Mo B -3

68.5

28.5

1.5 1.5

Ni-Fe-Cr 82 5

43 2 .2 3 30 2 1 .5 0.9 Ti

N i - F e - C r G-30 44 2

5 1 5 3 0

2 . 5 W ,

4Co

Ni-Cr-Si D-205

65

2 2 .5 6

20

5

S i

Ni-Cr-Mo

C-2 7 6 57 16 5 16

4W

Ni-Cr-Mo C- 4 68 16 16

Ni-Cr-Mo

C-22 56

13

3 2 2

3W

Ni-Cr-Mo

C-2000 60 1 .6 16 23

H2l 1 6

Reprinted from the February 2000 issue ofAdvanced Materials & Processes


2/6

mation

depend critically on the amount of over-

alloying

and the contentof minor elements, such

as carbon

and

s i l i c o n

Carbon iskeptas low aspos-

sible

in

th ewrought alloysby

special

melting

tech-

niques. Silicon is also held at

low levels

in

most

of

the

wrought

alloys,

since

it is a

strong promoter

of

second

phases. Indeed, this iswhy the

Ni-Cr-Si

ma-

terials are not

more

highly

alloyed.

In

cast

nickel

alloys, a small quantity of silicon is necessary for

fluidity during pouring. However, it heightens the

importance of the solution annealing and

quenching

processes

with

c a s t i n g s .

Nickel

alloyperformance

Although

the

numberof environmentsencoun-

tered

within

the chemical

processindustries

is

vast,

the

performance

of m e t a l l i c materials is

most often

based on

their resistance

to a few

aggressive

inor-

ganic chemicals.

These are predominantly hy-

drochloric acid, sulfuric acid, and hydrofluoric acid.

Also

very important

are the effects of residuals such

as ferric ions.

Caustic solutions:

The

most common caustic

so

-

lutions

are sodium hydroxide or

caustic soda

NaOH) andpotassium hydroxide

or

causticpotash

KOH).

Whencontamination

with

ironor

stress

corrosion

cracking is

not

a

problem,

these

sub

-

stances are sometimes handled

in

carbon

s t e e l ;

how-

Fig.

T he

higher the

content

of

nickel,

the lowerthe

cor

-

rosion rate in caustic solutions.

Fig.

Corrosion rateof three nickel alloys

in 30 NaOH

as afunction of the temperature.

ever, nickel and nickel alloys are the

metals

that

offer the

highest

resistance to corrosion in caustic

solutions.

F i g u r e

shows the corrosion rateof

sev

-

eral alloys in

boiling

50

NaOH solution.

The

higher thenickel content in the a l l o y , the lower

th e

corrosion rate.

The

corrosionresistanceofnickel is

a

consequence of the

formation

of

insoluble

metal

hydroxides

and salts,which slow down the

disso

-

lution rateof the alloy.

Figure 2 shows the corrosionrateof

three

alloys

in 30

NaOHas a function ofthe temperature.Ni-

200

o f f e r s

the

best resistance to corrosion,especially

at the

higher

temperatures.

Sodium h y p o c h l o r i t e

b l e a c h

can be

considered

a

m i l d l y

oxidizing

alkaline salt

that

canalso be

suc

-

c e s s f u l l y handledby

a nickel

a l l o y ,

e s p e c i a l l y

of

th e

Ni-Cr-Mo

group

(C-276

or C 2000 alloys).

Hydrochloric

acid:

Hydrochloric acid

HC1) is

very corrosive, and its

aggressiveness

can change

drastically depending on the

acid

concentration,

temperature, and

contamination

of the

acid e.g.

ferric ions). In general, steels, stainlesssteels, and

copper alloys

cannot

tolerate HCI .

O f

the

reactive

metals,

titanium does

notresist HC1

well

zirco-

nium is s a t i s f a c t o r y forpure acid, and

tantalum

of

-

fers

excellent

performance.

F i g u r e

3

shows

the

cor

-

Chemical

processes

most

often

involve

a few

aggressive

chemicals.

_I~ss

~oing ~15oc~

100- ~O/~OH

10- C-22

4

8250 06

Ni20060 0 0l0~

276 0 --2 0

1-

- 0

0.01

V

20 40 60 80 10 0

Nickel Content

Weight )

1

E+ 6

~ -T ~ 1

E+ 4

E Boiling Solutions

1E 5 316SS ~ 1E 3~

1E 4-~ lE 2~

lE 3-~-

18+2~

1E+0~

2

15 1 ~ IE-1

15 0

r I

~__~ ~702 0 -

15 .2

:c1~

Thnlalom.,

1E-1 T

~~

~1~

8

12 16 20

4 -

Hydrochloric

Acid

)

Fig. 3 Thisgraph

shows

the corrosion of

commercial

alloys

of stainless steel titanium nickel and zirconium

in boiling HCI solution.

5zi, UCI

s C-2000

~

3l6t~S

9 ~33

C276

4 400

023

1563 ~ 30 ~F 3 I

~ 54-200

1 E O 1

,5- 625

15 2 ~ / /

1E*0~

.5

1 1 5

~

15*1

~

isle

o

6~

0

3 1E*0

E-2

0

1E-1 ~ i 3

100 150 20 0 250 30 0

Temperature C)

1E+4

1E+3 ~

0~

S

5 15*2

Ct

0

15*1

50

15*0

15+2

a

5

1E*l

I

15-1 Ct

0

IE- 2

12 0

IC-I

0 40 80

Temperature

CC )

Fig. 4

Effect

oft/ic

temperature

on t he co rros ion rate of

nickel-basealloys and

316L

stainless s teel i n 5 HC1.


3/6

Temperature

0 to5

HC1

5 to 10

HC1

10

to

20 HC1

79C

to

B.P.

(175F toB.P.)

Ni-Mo

(B-3) Ni-Mo

(B-3) Ni-Mo (B-3)

52C to 79C

(125F to 175F)

Ni-Mo (B-3)

Ni-Cr-Mo

(C-2000)

Ni-Cu

(400)

Ni-Mo

(B-3) Ni-Mo (B-3)

RT to52C

(RT

to

125F)

Ni-Mo (B-3)

Ni-Cr-Mo

(C-2000)

Ni-Fe-Cr (G-30)

Ni-Cu (400)

Ni-Mo

(B-3)

Ni-Cr-Mo

(C-2000)

Ni-Mo (B-3)

Ni-Cr-Mo

(C-2000)

For

each

alloy group,

on e example

isgiven.

BP.

boiling

point, RT

=

room temperature.

Oxidizing

impurities

rosion behavior ofseveral alloys in boiling solu- Table

2

Nickel alloy selection forpure HC1*

tions of pure hydrochloric acid. At intermediate

acid concentrations, the corrosion rateof 316SS can ________________________________________________________

bemore than four ordersofmagnitude higher than

the corrosionrate of zirconiumor

B -3

alloy. ___________________________________________________________

Figure 4 shows the effect of

temperature

on the

corrosion

rate

of several nickel-base

a l l o y s and 316L

SS.

Formostof the alloys, the

corrosion

rate

grad

-

ually

increases as the temperature increases.

For C-2000 alloy, a threshold temperature is

reached,

below which the corrosion rate

isnegli

-

gible

due to passivation

of

the

alloy;

above the

threshold temperature, the corrosionrate increases

rapidly

as the temperature increases.

However, forthe

B -3 alloy,

the corrosion ratedoes

not

depend

strongly on temperature. The fact that

the corrosion

rate

ofthe

B -3

alloy at the boiling

tem

-

p e r a t u r e is

lower than the corrosion rateat temper- centrations

and

temperatures, whereas

316L

stain

-

atures below the

boiling

point, could

be related to less steel is

generally unsuitable forhydrochloric

the

amount

of dissolved

oxygen

at

each tempera- acid

service.

Alloys 4 00

and

82 5 may

be

adequate

ture

(which decreasesas the

temperature

increases). at

room

temperature.

The

nickel alloys

that

should be

considered for TitaniumGrade2, as well as the stainless steels

service in pure hydrochloric

acid

are

shown

in containing 6 molybdenum (such as

254SM0) ,

are such as

Table 2, a nine-segment chart organized by

con- resistant

to

low

concentrations ofHCI.

Theresis-

ftrric ions

centration and temperature. The selections are tance of ,irconium r-702 alloy) to

pure

hy- are

based

on

evidence that alloys from the chosen

drochioric

add

is

exceptional;however, in

the

pres

-

groups exhibit

rates

of 0.5

mm/y

(2 0 mpy)

or

less ence of ferric ions Zr-702

would be

subjected to

detrimental

over significant concentration

and temperature

pitting corrosion. Tantalum also

exhibitsexcellent to

Ni Mo

ranges,

within

those

segments.

Table 2 covers

only resistance

to

pure

HO solutions

up

to175C (350F),

concentrations up

to2 0

wt ,

the

maximum that

but it is

unacceptable

if

the HC1

solution is

conta-

an i U

can

be

sustained in aboiling solution. It indicates minatedwith fluorides.Fluoride ion impuritiesare allot~s.

that, of the nickel alloys, only those from the nickel- also damaging to titanium and zirconium alloys.

molybdenum

group are suitable at

high

concen-

Su~fitric

acid:

Sulfuric acid is the

mostwidely

trations

and

temperatures. used

acid

in

all

branches

of

industry. Sulfuric

acid is

In fact,molybdenum is

the

mostimportant al less

corrosive thanhydrochloric

acid, and its ag-

loying

element forgood

performance

of nickel-base

gressiveness

is highly

dependent

on acid concen-

alloys

in pure

hydrochloric

acid

educing condi-

tration, temperature, and the

presence

of impuri-

tions). The

corrosion

ratein boilingHO decreases ties. Figure 6 shows the corrosion rate of several

asthe content of

molybdenum i n

the alloy increases, alloys inboiling pure

sulfuric

acid. Sulfuric

acid

Oxidizing impurities

in

hydrochloric

acid,

such

aqueous

solutions up to

96

wt are

stable

at

the

as

ferric ions

(F ), are

detrimental

to

the

perfor- boiling

point.

mance of the nickel-molybdenum and nickel- However, theseboilingpoints increase

dramati

-

copper alloys.Under suchconditions, the nickel- cally at themedium and high concentrations. For

chromium-molybdenum

alloys constitute the

best

example, at 20 sulfuric acid, the boiling point is

choice,

because they

aretolerant of residuals, al- 104C (220F), at 50 is

123C

(253F), and at

80

is

though

they

are temperature-limited at the higher 202C

(395F).

TitaniumGrade 2 and 316L stain-

acid

concentrations. less steel are notadequate forsulfuric

acid

service.

Figure 5 shows the corrosion rateof several

al

-

loys inboiling 2.5 HC1 solution as a function of

theconcentration

of ferric

ions in the solution. The

corrosion rates of 316L SS and alloy

82 5

are

high,

and are not affected significantly by the presence

of

f e r r i c

ions.

Thecorrosion

rate

of

the

B -3

alloy

in

the pure boiling

acid

is

low,

but

it

gradually in-

creases as the

content

of ferric

ions

in the solution

increases. Thecorrosionrate of C-2000 in pureacid

is higher

than that

ofthe B -3 alloy;however,a con-

tent

ofonly 3 ppm Fe

3~

produces a decline in its

corrosion

rateby almost

two

orders of

magnitude.

The oxidizing ferric ions

promote the

passivation

of C-2000 by the formation of a chromium-rich

oxide film that reduces the uniform

dissolution

rate.

Figures

3, 4,

and

5 show

t h a t

the

nickel

chromium-molybdenum alloys suchas

C-2000

are

resistant to

HO in

a

moderately broadrange

of

con-

Fig. 5 Corrosion rate ofcommercial alloys in a solution of

I I C l contaminatedwithferric

ions.


4/6

Figure

6

shows that

theB -3 alloy has the

lowest

corrosionrate ofthe nickel alloys inboilingsulfuric

acid. Only at the highest acid concentration (>70 )

does

the

corrosion

rateof B -3

start

to increase.

The

strongconcentration effecton the

corrosion

rateof

zirconium alloy 7 02

is

also revealed.

Figure 7 shows the effectof

temperature

at a

con

-

stant

acid

concentration.As in the case of HC1

so

-

lutions

(Fig. 4 ) , the

temperature

has a

strong

influ-

ence on the

corrosion rate of Ni-Cr-Mo and

Ni-Cr-Mo-Fe

alloyssuch

as

C-2000

and G-30; how-

ever,

the

corrosion

rate

of a

Ni-Mo

alloy

(B-3)

is

al

-

mostunaffected by the temperature

low

activa-

tion

energy).

Table 3 shows the types of nickel

alloy

that

should be considered for service in pure

sulfuric

acid, depending on the acid concentration and

tem

-

perature.

The

selections are basedon evidence

that

alloys from the chosen groups exhibit

rates

of 0.5

mm/y

(2 0 mpy) or less over significantconcentra-

tion and temperature

ranges, within

those

seg

-

ments. The

important

revelationsof this

chart

are

the excellent

corrosion

resistance of the

nickel-

molybdenum

a l l o y s in

pure

sulfuric

acid,

thegood

resistance of

thenickel-chromium-molybdenum

materials,

and

the usefulness

of

several

groups

at

lower

concentrations

and temperatures.

Fig. 7

Th is g raph

shozos the effect of tens

perature

on the

corrosion

rate

of

several

nickel

base alloys.

The

presence of contaminants in

sulfuric

acid

could change the corrosionrate ofthe a lloys . F igure

8 shows the corrosion rateof alloysB -3 and C-2000

inpure sulfuric

acid

and in

sulfuric acid

contami-

nated with 2 00 ppm

chloride

ions s NaCl). The

corrosion rate of

both

alloys increases if the

solu

-

tion

is contaminated;

however, the effect seems

more pronounced for

the

Ni-Cr-Mo

alloy.

Hydro,fluoric

acid: Hydrofluoric

acid

is extremely

corrosive and unique in its corrosion behavior.

Many industriesuse it as anaqueous solution, as

a

fluorinating

agent,

for

metal pickling,

and in

the

manufacturing

of semiconductors.

Nickelalloysare the

only

alloys that arewidely

chosen forhandling aqueous solutions ofhydro-

fluoricacid,

because

stainless steels, titanium, zir-

conium,and tantalum are

not

adequate for this ap-

plication.

The

most

common alloy for handling

aqueous

hydrofluoric

acid iswroughtMonel 400.

This alloy has excellent corrosion resistance in the

absence ofair or

otheroxidizing

species; however,

if

oxygen is present, itis subject toaccelerated inter-

granular attack,

especially

in thevapor phase.

Figure

9

shows

the

corrosionrate

of three nickel

alloys in the liquidphase immersed conditions),

and in

the

vapor phasewherevapor condenses

on

the

coupons

(forthese tests, the ingress of air to the

testingkettles

was

not restricted).

Alloy 400 corrodes athigh rates in the vapor

phase,

because

of intergranular attack.

The

corro-

sionrate of alloy 4 00

is

higher at

thehigher

tem-

perature,

both

for the liquid andvaporphases.

Thecorrosion

rate

of theB -3 alloy

is

lowerin the

vapor phase

than

in the liquid phase. Moreover, at

thehigher temperature, its

corrosion rate

inboth

phases

is

lower. In general, thecorrosion rateof B -

3 is

not

highlyinfluenced by the temperature;

there

-

fore, the lowercorrosionrate at the

higher

temper-

ature

can

be

the result of

a

lower

availability

of

oxygen

both

in the liquid and vapor phases. The

B -3 alloy is subject to

pitting

corrosion inHFenvi-

ronments,bothin

the liquid

and vapor

phases.

The C-2000

alloy

showed

the lowest corrosion

rate in all the

tested

conditions.

Laboratory

testing

hasalso shown

that

the

corrosion

rate of C-2000 in

Fig. 8

This

graph

shows the

effect

ofcontamination by

chlorides

in sulfuric acid on a llo ys B -3 and C-2000..

Hydrofluoric

acid is

extemely

corrosive.

20 40 60

Sulfuric

Acid

Concentration C /

Fig. 6

Corrosion

rate in boiling sulfuric acid.

1E*3 ~

Immersion

r sts

Boiling Solutions

Full

Syrnbols~

Mded

200

ppm C1

s

is-I

v C

2000

1E+3 ~--- --------- - i

60

i-i

2

so

4

lE+l

~ C2000

1E+2 ~

~g

:H-u B-I

5

4 1 0

L

1El

Ct

0

I- -

1E+0 -

I

B. P

I

IE-1 ~ ~ ~- C~

0 40 80 120 180

Femperature

C)

t

a

15+0

I

1E-l ~

0

St

0

to

15*1

-C

1 E C 2

1E-l

3

C

It

1E*0

I

1E-l ~

if

0

C

N

-rr

l

1F-2

IE-l--

1

I 3 ~

0

20

40

H

2

S0

4

Concentration ~

60


5/6

Table3 Nickel alloys forpure

sulfuric

acid*

thevaporphase

is

time

dependent;

that

is,

the rate

decreases

as the

test

duration in-

creases.

Thisisprobably dueto the

gradual

development of a protective

film

on the

surface.

The

corrosion rates of alloys 4 00

and C-2000 in the liquidphase do

not

depend on

the testing time.

Nickel-base alloysare

susceptible

tostress

corro

-

sioncracking in

the

presence

of

aqueous solutions

ofhydrofluoric acid.

Not

all

nickel alloysare equally

susceptible toSCC

under

thesame conditions; that

is,

cracking isstronglydependenton several variables,

such as alloy composition, temperature, presence

of

o x y g e n , and

liquid vs.vaporphase.

Mixtures

of

hydrofluoricandnitricacid

are typ-

ical in

themetal industryforpickling

processes. In

a solution of 20

HNO

3

containing different

amounts of h y d r o f l u o r i c acid, the lowestcorrosion

rate corresponds to G-30 , a Ni-Cr-Fe

alloy

con-

taining30 chromium,

The

high

chromium

con-

tentpromotes

the

formation

of a

passive

film in the

oxidant nitric acid, and

does

notseem tobe readily

attacked

by thehydrofluoricacid.

Other acids:

Phosphoric acid (H

3

PO

4

)

is

not

highly

corrosive

to

nickel

alloys.

Two distincttypes

of

phosphoric acid

are

encountered

in

the industry.

The

pure

reagent

grade) acid ismade from ele-

mental phosphorus, derived fromphosphate rock.

This is oxidized, then

reactedwith water.

Onthe

otherhand, the preferred

type

ofphosphoric acid in

the

agrichemical

industriesis madeby reacting

phos

-

phate rock

with sulfuric acid.

This

containsseveral

impurities, notably sulfuricacid, s i lica, and chloride

and fluoride ions,

which

markedlyaffect the corro-

sionbehavior

of the acid. The

levels

of these impu-

rities

vary

dependingon the source of the rock, and

differentbatchesof this so-called wetprocessacid

can

vary

considerably in their corrosivity.

The

G-30

alloy is

generallypreferred to handle

the wetprocess phosphoric acid. Forpure phos-

phoric acid, Ni-Mo (B-3), Ni-Cr-Mo (C -276 , C -2000)

and Ni-Fe-Cr (G-30) alloys can function in up to

85 acidup to theboiling point.

The

corrosion

behavior of hydrobromic acid

HBr)

is

similar

to

that

of

hydrochloric

acid;

how

-

ever,HBr is less

aggressive. Therefore,

when

pure

and hot,HBr isbest

handled by

a Ni-Mo alloy

such

as the B -3 alloy. -A

Ni-Cr-Mo

alloy

such

as C-2000

isversatileand is s u i t a b l e for

most

applications

con

-

taining HBr, especiallyin solutions contaminated

Temperature

0 to 30 H

2

S0

4

30 to 70 H

2

S0

4

70

to96 H

2

S0

4

79C toB .

P.

175F to B.P.)

Ni-Mo (B-3)

Ni-Cr-Mo C - 2 0 0 0

Ni-Fe-Cr

G - 3 0

Ni-Cr-Si (D-205)

Ni-Cu

(400)

Ni-Mo (B-3) Ni-Mo (B-3)

52C to 79C

(125F to

175F)

-

Ni-Mo (B-3)

Ni-Cr-Mo (C-2000)

Ni-Fe-Cr (G-30)

Ni-Cr-Si

(D-205)

Ni-Cu (400)

Ni-Mo (B-3)

Ni-Cr-Mo

(C-2000)

Ni-Fe-Cr (G-30)

Ni-Cr-Si

(D-205)

Ni-Cu (400)

Ni-Mo (B-3)

Ni-Cr-Mo (C-2000)

RT

to

52C

(RT to 125F)

Ni-Mo (B-3)

Ni-Cr-Mo (C-2000)

Ni-Fe-Cr

(G-30)

Ni-Cr-Si

(D-205)

Ni-Cu

(400)

Ni-Mo (B-3)

Ni-Cr-Mo C - 2 0 0 0

Ni-Fe-Cr (G-30)

Ni-Cr-Si (D-205)

Ni-Cu

(400)

Ni-Mo (B-3)

Ni-Cr-Mo

(C-2000)

Ni-Fe-Cr

(G-30)

Ni-Cr-Si (D-205)

For each al loy

group,

on e example is given.

withoxidizing species.

Organic acids

such

as formicand acetic

acids

are

nothighly corrosive for

nickel

alloys.

At

tempera-

tures

higher than 100C (212F) , the B -3 alloy

Ni-

Mo) would offer the lowestcorrosion

rate.

N i t r i c

acid

is a

strong oxidizing

acid

which be

sides zirconium and titanium alloys, can

behan

-

dled

with

stainlesssteelsornickel alloys

containing

at least 15 chromium othernickel alloyssuch as

B-3, Ni-200, andMonel 4 00 cannot

be

used in nitric

acid). For

mostpurposes,

anickel alloy

isnot

re-

q u i r e d

to

handle

nitric acid;however,nickel alloys

resist corrosionbetter

than

s t a i n l e s s steels in cases

where the

nitric

acid

is

contaminated

with

chlorides. R

Fo r

more

information: D r. Rail

B .

R e b a k

(765/456-6262) ,

is a

Corrosion

Engineer;Paul Crook ( 7 6 5 / 4 5 6 - 6 2 4 1 )is

Manager, Technical Services,

at

Haynes

Intemational,

1020

W.

Park

Ave., Kokomo, IN 46904 ; e-mail:

[email protected]; [email protected];

Web

site:

www.haynesintl.com.

References

1. Corrosion Engineering, by MG.

Fontana:

McGraw-Hill ,

Inc.,

New

York , N .Y . ,

1986.

2.

Process

Industries Corrosion Theory

and

Practice, by

J .K.

N e l s o n :

NACE

Intemational, Hou ston,

Texas,

1986.

3.

Corrosion

Control

in the Chemica l Process

Industries,

by

C.P.

Dillon:

NA CE International , Houston, Texas, 1994.

Corrosion

Resistance

Tabie,~,by P.A. Schweitzer, (New

York,

NY ; Marcel D ekker ,

Inc.,

1995.

5

T a p e r

382, by

JR .

Crum

G.D. Smith,M.J.

McNallan,

and

S H i r n y j : C o r r o s i o n / 9 9 ,

N E International,

Houston, Texas, 1999.

Phosphoric

acid is

not

highly

corrosive

to nickel

alloys.

12

U

400

Nickel-base

alloy

Fig. 9

Corrosion

ofnickel alloys in hydrofluoric

acid

liquid

an d vapor.


6/6

A n a h e i m

C a l i f o r n i a

9 2 8 0 6

S t a d i u m

P l a z a

1 5 2 0

South

Sinclair Street

T e l : 714-978-1775

8 0 0 - 5 3 1 - 0 2 8 5

F A X : 714-978-1743

Houston, Texas 77041

The Northwood Indus tr ial Park

1 22 41 FM 52 9

T e l : 713-937-7597

800-231-4548

F A X : 713-937-4596

Arcadia, Louisiana7 1001-9701

3786

Second

Street

Tel:

318-263-9571

800-648-8823

F A X : 318-263-8088

C h e c k o u t o u r w e b s f t e : w w w

0

h a y u e s n t i c o m

I

ter,Ml 2ER FAX: 39-2 2 82 82 73

T e l :

4 4 -1 6 1 2 3 0- 7 77 7

F A X

4 4

16 1 2 2 3 2412

France

HaynesInternational, S.A.R.L.

S w i t z e r l a n d

Nickel Contor AG

Zl des Bethunes

10 ru e de Picardie

95310 Saint-Ouen LAumone

T e l : 33-1-34-48-3100

F A X 33-1-30-37-8022

Hohlstrasse 534

CH-8048 Zur ich

T e l : 41-1-434-7080

F A X : 41-1-431-8787

ll

t r e m r ks

a re o w n e d b y a y n e s I n t e r n a t i o n a l I n c

alloys for corrosive environments nickel

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