Evaluation of resistance of stainless stabilized steels to intergranular corrosion

Evaluation of resistance of stainless stabilized steels to intergranular corrosion

Materials Chemistry and Physics,19 (1988)447-461 EVALUATION OF RESISTANCE INTERGRANULAR A. KARAS, FOLD1 V. 447 OF STAINLESS STABILIZED STEE...

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Materials Chemistry and Physics,19 (1988)447-461

EVALUATION

OF

RESISTANCE

INTERGRANULAR

A.

KARAS,

FOLD1 V.

447

OF STAINLESS

STABILIZED

STEEtS

TO

CORROSION

CfHAL

and

V.

[
27.2

62,

V.

SONP,

VANEK (C.S.S.R.)

CfHAL

State

Research

Praha

9,

Institute

Bechovice

of

190

11

the

Protection

of

Materials,

(C.S.S.R.)

Received September 7, 1987; accepted October 14, 1987

ABSTRACT Relationships and

the

between

parameter

of

susceptibility relying

of

on

the

CrNi

their

applicability

culary

ateels,

suited can

integrity

to

of

discussed

in

stabilized

use

at

the

to

modify

the

not steel

the

final

as

Obviously,

the

In

that

the

case

normal

appears value

the

of

including

the the

stabilization

0254-0584/88/$3.50

accurate data

coefficient

in

the

is

to parti-

since

trimming before

the

continuity

steelmaking by

would

evaluation

of

high.

effect

relation

auste-

composition

products test

indicating

treatment

surprisingly

in method

Furthermore, of

the

low-carbon

steelmaking,

II.

this

efficiency

solution

paper The

assess

corrosion to

chemical

final

to

contents

and

making

be

the

carried

the

test out

on

prescribed.

most

includes

this

disturbed

into

corrosion;

carbon

derived

applied

of

the

parameter be

intergranular product

stage

and

intergranular

steels.

made to

were

to and

be

the

that

analysis,

for

calculation

k

chromium

steels

for

would

processing

resistance

were

referring

teeming, and

effective

stainless

chemical

nitic

additions

the

On of

of

contrast

the

degree

of

obtained

if

chemical

analysis.

stabilization

and

sensitizing

at

the

other

the

efficiency

nitrogen to

is

complete

the

is

hand, for

significant

other

tramp

the

the

for

650°C/l

h/air

relatively

calculation for element-

lower without

the

degree the

of

sulphur,

0 Elsevier Sequoia/Printed in The Netherlands

448

INTRODUCTION Stainless and

such

steels

with.which

hazard

several and

power

not

of

only

in

contents

carbon

and

corrosive

balanced

loads to

corrosion

factory,

or

if

structurally changes

ments

are

can

be

chemical is

their

also

take

with

guaranteeing to

the

chemical

the

CrNi

Eauations

at

of

of

satisin

that

hardly

These

require-

steelmaking methods

which to

The

make

modify

present

procedures

the

paper

proposed

corrosion

with

stainless

a

of

chemical

is

incidence

paramet.er

a

resistance

of

on

for

reference

austenitic

the

steels,

[1,21.

point

and

stepwise

complemented

elements

in

alloying

susceptibility

specially to

intergranular

low-carbon the and

resistance

Taking

as the

with

of

type and

limit

on

to

/i/ of

the

the

Crl8Ni.10

determined

and

chromium

from

/ii/

the

inter-

chromium

basis

effects

molybdenum, corrosion

a

of

contents

the

steels and

both

indicating

contents

between

stainless nickel

corrosion

corrosion,

effective

dependence

Cr17Ni12Mo2,

of

equations

sufficient

proven

carbon,

interaranular

intergranular

indicating with

to

composition

based

starting

of

so

stage.

stabilized

re-

are

measures

the

me-

their

those

suitable

intergranular

empirically

of

of

severe

drawings.

only

inspection

one

stabilized

that

grades

and

not

steelmaking

to

analysis

corrosion, as

proven

design

of

which

with

of

heavy-duty

properties

corrective

the

use

and

provided

with

contents

in

identical

appropriate

the

steels

conditions

carbon

using

on-the-spot

specification

granular

the

by

determinina

stabilized

of

and

modified

type.

for

The

are

elements

steels

reduced

in

only

mechanical

in

resistance

of

value

and

composition

concerned

and

them

properties

possibly

low-carbon

applications

to

tramp

stabilized

application

on

needed

to

find

mi-

in

given

and

with

in

established

but

possible

in

The

can

and

satisfied

technologies, it

types,

also

and

engineering

therefore

CrNi

corrosion

required

chemical

is

steels

and

guaranteed

alloying

imposed

their well

in

composition

are

in

of

composition. steels

are

sistance

or

is

incurred,

attention

but

carbon,

environments

chanical

is

content

nitrogen,

stainless

service

especially

low-carbon

and of

a

austenitic

chemical properties

failure

balanced

austenitic

normal

any

and

Maximum

suitably

molybdenum

optimized

in

industry,

engineering. a

with

reliability

damage

branches

seeking

with

of

alloys

physico-metallurgical

mechanical,

resistance nimal

and

rest and

the by

degree the

449

corresponding ship

k

was

=

-

this

resistance

the

100,

content reliably k =

k

Cr.

=

Cr

+

c*

=

C +

The

coefficient

1.0

and

kl

is

CrNi

of

The

of

in

may

be

the

the

parameter

equal

to

inter-granular

to

in

the

in a value

when

of

appear

addition

corrosion,

has

data,

is

mild may

factors

niobium, d,

value

silicon,

16; attack

steels

having

effect

of

decisive

for

and

include

they

the

degree grain

relationships chromium

and

are carbon

satisfied (in

wt.

for %),

the

respectively:

(2) (3)

in

eqn.

molybdenum

in

taken,

with and

and

is

(2)

for

CrNiMo

on

to

the

the

this

288OC

[ill

oxygen

at

100

H2S04, h/air

110

the to

1.7

with

the of

be

equal

passivating

was

used

ranging The

value

test

in

2.2 the

current in for

a

Cu;

a

sensibilization

this

standard of

(see

Fig.

effect

of

density

solution

water

. g CuS04.5H20,

between of

evaluations

to to

measurements value

values

results

referring

critical

111;

up

conditions.

steels,

than

take

comparison

potentiokinetic

% KSCN

may

different

reference

lower

polarization

ml

and

thermodynamic

factors

effective and/or

constant

resistance,

16,

the

of

etc.

general

[l,g,lO]

and

650°C/1

% [7,8].

intergranular

b

1.7

value

x)

0.05

is

nickel

titanium the

chromium,

(Ni-kZ)

The

of

the

C*

of

of

improvement

b MO

coefficient

0.01

with

and

the

and

[4-6]

other

14

contents

solution

relation-

corrosion.

content

effect

occurrence of

deformation,

following

to

these

to

cold

effective

+

limited

between

the

sufficient

composition;

The

carbon

around

the

sensitivity

size,

general

(:

on

elements,

harmony

Effects

of

chemical

a

intergranular

effective

corrosion, by

ensures

14,

to

molybdenum

According

is

tolerated. value

the

of

stabilizing

in

carbon

is

modified

steels.

k

of

Cr.

intergranular

and

that

‘I,

parameter

resistance

effect

carbon

stabilized

a

the

the

to of

to

the

I31

(1)

also

nitrogen

solution

indicating

relationship

content

is

for

indicates

including

when

standard

&C‘

value

equal

in

derived

Cr.

whose In

test

containing

lowI).

chromium in

of

H2S04 36

+ ppm

0

lCL473BC

13<

ICL167 CN EL 167F

$ + traces m*

susceptible

C’I%l

-

1. Results of testing steel grades ICL 473 BC sentitized at Fig. 7OOoC/30 min/5OoC/h and steel gradfs ICL 167 CN and ICL 167 F with optimized chemical sensitized at 725oC/30 min/50°C. h for resistince to intergranular corrosion composition (see below), in standard solution (10 % H SO + 10 % CuSO . 5 H 0, 70 h, plottins: dependence of4the ef?ective content boiling) ; bend test; of chromium on the effective content of carbon (in wt. %) according to the equations with coefficient b = 1.2. The lines for the parameter k demarcate the incidence of low-intensity intergranular corrosio’;;. The parameter below which the steel is not safe against intergranular corrosion is equal to 25.7 according to the set of melts investigated. chemical

grade Creusot-Loire

C

ICL 473 BC ICL

0.04

167 CN

ICL 167 F

Mn

Si

1.0

2.0

analysis,

% by

weight

Cr

Ni

MO

18.5 20.0

9.0 10.0

/0.15/

N

B

0.08

-

max.

0.045

1.0

2.0

17.0 18.2

11.5 12.5

2.3 2.8

0.08 max.

0.03

0.5

1.6 2.0

17.0 18.0

12.0 12.5

2.3 2.7

0.06 0.08

0.015 0.0035

Bearing in mind the statistical nature of the testing [5, 121 done to validate the constants k, and k2 in eqn. (31, the value of kl will be 0.002; for chromium of

carbon

content

is

the

following

= C + 0.002

(Ni-3.0)

a about

constant 19

%,

relationship

k2 so

it

will

that is

for used

be

around

the

for

effective

20

when

the

content

non-stabilized

steels: c.

(4)

451 The

value

melts

of

of

treatment 1

than

h/air;

to

the

see

141, a

tionship

1.

of

that

and

contents

to

the

is

of

on

the

of

a

Ti

in

where

Ti

tanium

content

can

the

is

the

titanium

solid

solution. be of

fairly

stable

since

do

differ

not

carbides

at

sulphur

in

Using bound

TiTiN

where

to

steel

nitrogen

3.43

N

is

of

in

bound

extent the

of

high

titanium)

niobium.

the

Relying

total in

content

this

to

carbon,

a

parti-

manner. bound

nitrogen

nitrides

dissolve

to

be

to

indicate

bound

to in

much

Roughly

a

to

S tg

is 7 total

is

free

of

is

Ti2S

content

steels

readily the

ti-

niobium

nitrogen

less

the

nitro-

stabilized

half

the

the

Ti

the

similar

TiTi

bound

and of

element

and

of

steel,

titanium

distribution

of

means

of

the

stabili-

what

excess

titanium

contents

by

niobium

(5)

the

rated

or

follows:

the

temperatures. is

staand

exceeding

titanium

is

in

relationship

in

of

16.2.

rela-

carbon

to

of

i.e.

TiTiN

stabilizing

much, higher

the

=

a

carbon

to

+ Tir

The

indicated

content

the

degree

that

distribution

limited

into

Furthermore,

to

content

sulphur,

the

(i.e.

as

is

titanium

deciding

titanium

steel,

+ TiTiC

total

as

for

expressed

to

could

The

be

of

111,13,

15.7

both

heat

650°C/

=

contents

contrast

the in

bound

TiTiC in

in

of

bind

ratio

to

k

included

their

at

steels

content

mass

of

demanding

these

perfection.

with

el.ement

more

niobium

(or

industrial

conditions

parameter

be

referred

media,

+ TiTiN

is

titanium

or

reliable

knowledge,

instance,

= TiTi2S

gen,

some

in of

effective

approaches

present

zone

inspecting

sensitizing

rather

values

the

by

stricter

normal

shall

also

completely

stabilizing

cular

the

content

stabilization

adverse

thus

elements,

stabilization

degree

the

the

ratio, not

to

titanium

carbon

to

is

stabilization

other

stoichiometric is

to

Since

the

determined

apply

transition

indicates

steels.

zation)

The

pertaining

nitrogen

k,

steels,

corresponds

effect

bilized

parameter

sensitization

Fig.

range

The

the

low-carbon

than

content

[15,16]. of

titanium

I171

(N-0.001)

the

content

of

(6)

of

nitrogen

(in

wt.

%)

then,

for

titanium

452

bound

to

TiTiC

=

and

carbon,

Ti

-

we

1.5

thence,

=

f

where the

f”,

the

and

upon

of

nitrogen

is

The

not not

and

for

be

equal

C.

=

heating

paper

is

S

concerned

efficiency; content

determining

the

with

of

only

of

content

the

content

of

of

sulphur

in

finding

out

the

are

necessary

for

Ti-stabilized

k

-

the

the

of

wt.%.

values

carbon

of

for

resistance

to

stabilization-annealed would

that

parameter

k,

relationships

non-stabilized

steels;

for

the

values

of

the

carbon

will

values

contents

coefficient

chemical

of be

roughly

never

of

-

CTiC

C. = C + 0.002

(Ni_10)

_

f

Data

are

lacking

and

other

still

elements,

on and

unequivocally

the

of

the

occurs

will

of

the

effective

these bound

efficiency,

expressed,

composition

(Ni-10)

included

compo-

the

values

in

the

C +

if

if

efficiency

phenomenon

content

chemical

f

in-

content

parameter

is

coefficients

0.002

be

the

these

effective

a

f”

is

TiC

titanium

of with

including

carbide

and

compared

coefficient

It

of

period

and

of

(8)

efficiency,

incompleteness f*

-

of

dissociation

the

content the

the

the

and

unity

(N-0.001)

coefficients

determine

respective

of

S-3.43

approach, in

a metal

treatment.

derived

the

Ti-1.5

of

either);

to,

(7)

carbon,

to

contain

Tir

bound

order

carbon been

the

known,

the

solution In

are

corrosion.

that

f

-

4

known

the

intergranular

after

f

of

calculating

or

S =

(coefficient

present

steels

of

and/or

coefficient

grades

content

temperature,

steel is

sulphur

(N-0.001)

understanding

solution,

sition

3.43

4

f‘

solid

write

f*Ti-1.5

of

dependence

the

-

-;;_ =

lack

in

S

for

NaTi CTiC

can

be

used

depending as

of

that

had

relationships carbon

so

steel,

content

will

together

that

the

upon

with

effective the

knowledge

follows:

(9)

Ti

-

the

1.5

effect changes

into

the

S 4

of in

3.43

(N-O-01)_

manganese, their

relationships

(10)

silicon,

contents

can

discussed

boron hardly in

the

453

foregoing.

However,

negligible

within

stabilized

austenitic

steels

with

effect

of

of

tests

used the

to

nular

the

corrosion

present stabilized

-

steels

chromium to

obtain

or

f”

and

are

not

silicon,

be in

Ti-

apply

where

the

of

the

to

the

melts

in

possibility

mind

for

k

-

the

18

were to

the

of

sus-

intergra-

subject to

the

values,

[3]

Ti-stabi-

the

between

of

standard

corrosion

resistance

of

the

of

stainless

Having

parameter

determinant

of

these

for

ranges

and

intergranular

relationships

or

occur

does

analyses

grades

Out

I).

and

will

titanium

to

four

test

Table

using

or

chemical

assessment

values,

which

of

steels.

carbon,

the

with of

standard

the

normally this

manganese

resistance

(see

paper

they

effect

ignored.

melts

CrNi

after

their

Still,

stabilized

232

that

which

of

be

indicate

austenitic

ceptible

in

accumulated

of

assumed

steels.

contents

steels

basis

lized

limits

cannot

were

be

CrNi

higher

Results

may

the

these

Evaluation

on

it

of

contents

prime

of

concern

was

coefficients

efficiency

of

the

evaluate

f,

the

f‘

degree

of

stabilization. First,

effective

melts,

and

tationally basis

of

were

rosion

for

f

these.

parison

the

of

lected all

fairly

Table

included

I);

those

in

further

Effective

content

melts,

ferent

values

and

to

a

the

accuracy

amitted. susceptible

obtained,

intergranular

melts

degree of

A

were

corThis

to

calculations

86

of melts

values

coeffiwere

intergranular since

the

high

stabilization

values of

com-

of

with

of

the

total

the

indicating

calculations f:

high

on

attack.

further

the

calculated

14-16,

corrosive

all orien-

which

=

efficiency

with

of

of

the

0.5

sulphur,

were

included.

comparison values

to

of of

5

was was

coefficient

from

limit

carbon

parameter

starting

A

k

for

calculated

se-

corrosion

their

number

was

small.

lected

its

of

for

of

were

then

parameter

this

point

calculated was

susceptible to

to

efficiency,

was

carbon & was

this

steels

those

i.e.

of

values

resistant

contribute

(see

were

of

limit

starting

k,

cannot

cients

values the

coefficients

parameter

that

chromium

parameter

between

the

of content

unity;

The

steels

was of

=

with

points and

values of

effective

compared

breaking

content

the

unity;

the the

then also

of the

calculated resistance

calculated

efficiency

content

values

for

calculated

of

of

pertaining

for f

both

at

the the

.lO

nitrogen

rhe

parameter to

individual

sedif-

steps and

k

with

08Crl8NilOTi

0.08

1.5

2.0

0.10

09Crl8NilOTi

417248

2.0

0.12

lCrl8NilOTi

Mn max.

number

C max.

the

austenitic

2.0

417246

&N

and

of

0.12

lCrl8Ni9Ti

types)

Specification

grade

321

(AISI

type

I.

Table

0.8

1.0

0.8

1.0

.

;;‘;

.

17.0 lg . o

17.0 19.0

;;‘;

Cr

investigated

Si max.

of

stainless

.

;;‘;

1;‘:

.

.

9.0 11.0

l;‘;

Ni

of

5.C/O.6

5.C

5.C/O.8

5(C-0.03)

0.035

0.045

0.035

0.045

P max.

these

stabilized

Ti min/max

heats

steels

0.012

0.030

0.020

0.03

S max.

steels

with

78

14

50

90

total

titanium

%)

18

9

23

26

number of selected

(wt.

1

5

4

8

melts susceptible

455

09Crl8NilOTi lCrl8NilOTi lGrl8NI

l

9Ti

08Crl8NilOTi susceptible 4.

+ A

0

+e

c

*A+:;;

t

l

+A A

l

A A

.

+ ++

A

A: l

+ A

l l

0

0.04

-

0.08

0.04

___)

c' [%I

Results of testing resistance of stabilized steels to Fig. 2. intergranular corrosion (selected melts) after testing according to CSN 03 8169 in standard solution for the value of the coefficient of efficiency of the degree of stabilization f = 0.98 and constant b = 1.2, plotted to show the dependence of the effective content of chromium on the effective content of carbon with reference to the transition zone for the incidence of susceptibility to intergranular corrosion with k = 14-16 coefficients the

known

of

The

comparison

ing

point

Fig.

2).

the

line

terms

of

dependences (see

two

melts,

granular limit

of with

f

=

lies To

the

effective

the

for Fig.

the 3).

of of

value

in (steel

of

the

k =

the of

14.

of

of

test

of the

the break(see

out

from

corrosion of

f

=

of

0.96; f

for

resistance

to come

in

chromium

presented

coefficient

type)

calculated,

where

the

lCrl8NilOTi

comple-

values

stand

content

efficiency

is

corrosion

melts

are

(IO)

0.96;

thus

intergranular

sections

of

carbon

optimal

some

a

0.94;

intergranular

effective

value

0.92;

position

to

carbon,

the

satisfactory corrosion

to degree

coefficients As

the

resistance

dependence content

give

to

eqn.

composition

Therefore, =

content

resistance what

f

(,

to

chemical

unity.

values

relation

to

according

the

and

for

parameter in

demarcates

the

0.9

made

the

that,

where

between

0.98 for

that

showed

was

illustrate

effective

0.92

the

lay

values

coefficient

f,

coefficient,

calculation

0.98.

the

efficiency

this

completely,

mentary

on

of

value

on these

0.94;

decreases, interdown

below

456

+ lCrl8NiSTi

$ 19 . 6

I 18

17

0

0.02

0.04 0

Fig. 3. Comparison of transition zone; three ciency f are shbwn.

0

0.02

a04

results lower

0

oQ2 from values

0.02

aD4 Fig. of

0

oD2 -

2 in the vicinity the coefficient of

a04

0

O-02 -

Fig. 4. Comparison of results from Fig. of efficiency f‘ in the vicinity of 0.7; is not included.

0.04 C' [O/o]

3 for three the effect

of the effi-

004

c’ [Vol coefficients of nitrogen

The

calculations

plotter. on

the

chemical

contents

of

nitrogen

of

efficiency

content

of

(coefficient and

inc;luded.

mutual parameter of

In

2

will

efficiency

and

is

f‘

not

show

that

0.7

the

the

(see

optimal

Fig.

chemical

For

analysis both

the

f”)

are

calculations

having

value

4).

coef-

which

efficiency

the

melts

the in

where

of

HP 9862A data

sulphur,

instances

both

heats

and

include

instances

in

for

instance

selected

the

indicated

9810A

always even

for

or

HP

not

(coefficient

former

of

=

do

sometimes

f‘),

contents

the

comparison

computer

calculated

efficiency

sulphur

using

analyses

was

nitrogen

of

nitrogen not

made

the

ficient the

were

Since

of

the

and

limit

a

values

the

of

coefficient

value

of

f”

=

0.72

one of the unsatisfactory melts closely approaches the value of parameter E = 16, although none of the satisfactory melts is below the limit for the parameter k = 14. In the latter instance the value of the coefficient f" ficiency for

of

the

stabilization

resistance

mical

The

and

in

it

and

the

the

stabilizing

These

to

only

steels.

Since

lected

values

of

stabilization carbon

will

doubtedly

be

Neglecting content

for of

the of

be

used,

added

the

effect

chromium

che-

The

both

is

given

molybdenum

produces

an

obtained

much in

essential

the

of

steels

the

with

the

degree

will

val.ue

seof of

be

MO-modified

effect

manners,

stabilized

content

attention

of

directly.

complete, of

and

required.

quantity

also

effective

knowledge

Nb-stabilized

latter of

the

or

not

efficiency

the

will

quickly

a variety

but is

where

calculated

in steels

composition

steels this

available or

be

the

austenitic

soon,

must

re-

in

teeming;

made

[7,8,11-141,

where

metal

composition

modified

the

susceptibility

the

be

low-carbon

reduced

to

inducing

before

very

coefficient be

and

complete

composition

stabilized

must

to

chemical the

the

chemical

be

calculated.

useful

evaluation

the

stainless

will

their

ef-

possibility

calculated

chemical

conditions

composition

the

a

referring

the of

calculated

can

chemical

be

heat-affecting

analysis

element

not

on

enable

trim

be

relationships

assess

by

chemical k

to

studies

based

zone,

parameter

optimized

these

industrial

realistic

offers

although

principles

in

the

steels

are

corrosion

assessed

0.66

known,

that

temperature

be

to

exactly,

physico-metallurgical

Obviously,

The

not

obtained above,

intergranular

make

to

is

results

critical to

austenitic

no-t. quite

composition

lationships

to

of

though

evaluated,

is lower (see Fig. 5). The

equal

f”

un-

grades. at

present.

of

the

affective

on

the

final

the

458

a OBCrl8NilOTi

i

18

0.02

Fig. 5. Comparison of the effects of neither

of

more than or

the

content

of

less

original tuated of

steel

steels

are

these

equations

and carbon.

a tramp element. the

Obviously, calculation the

case

normal

the is the

the

significant

other

efficiency

On the of for

tramp element parameter

other

of the

5 does

of

their

of

hand, f‘

nitrogen degree

- the not

these

of

sulphur. greatly

the

= 0.7 is

of

types

kept

fluc-

being

somewhat

the

of close

if

chemical

composition.

of

the

steels

for - 1050°C/

- appears

relatively

Omitting

contents

effect

obtained

the

lower calculation

an indication

reduce

to the

contents

stabilization

h/air

stabilization

on

in a quantity is

for

contents

effective

include

complete

f”;

detrimental.

form the

degree

of

furthermore,

authors

evaluation the

nickel

nickel

indicate

at 650°C/1

efficiency

effect

the

when present

of

treatment

of

equally

the

indicating

and sensitizing

high.

coefficient

including

data

solution

30 min/water prisingly

the

beneficial

most accurate

includes

is

The calculations

which

In that

is

spite well

to

for

0.02 0.04 C’ [%I

-

depends,

[II,

in which

molybdenum, that

effects

concerned,

equations

8 and 12 %; in

between

chromium

different

than 10 %, which in

empirical

complicated,

the

chromium

Where stabilized

"0

results from Fig. 3 for three values nitrogen nor sulphur are included.

I201 . Neglecting

result

0.02

-0

0.04

of in

of

without

how nitrogen

contrast

sulphur

the value

survalue

to

the

in calculating of

the

coef-

459

ficient

of

efficiency,

negligible, =

as

although

is

documented

the

effect

the

fact

basis

of

by

of

sulphur

that

the

is

not

value

of

f”

=

0.66. The

results

equations made

obtained

were

according

However,

to

this

sistance

to

tents

of

on

the

orientationally

compared

equation

equation

based

is

not

intergranular

titanium

on

apt

a

to

corrosion

and

other

the

above

empirical

with

the

calculations

statistical

analysis

reliably where

elements

is

indicate the

range

of

1211. the

re-

the

con-

wide.

CONCLUSION Relationships

between

carbon

and

the

assess

the

susceptibility

corrosion

relying

carbon

austenitic

relation

to

The

of

bound

content

of

carbon.

(or

f‘,

a

f”, of

study

from

of

according and of

as

232

the

to

melts

the

in

the

of

nitrogen

CSN

the

to

neither value

The results

of

range

content the

not of

0.7

types

their

the

to

is

to

of

of

to

the

of

chemical

nitrogen

coefficient

of

re-

Where

the

calculation,

the

CSN

quoted).

and

is

the

completbasis 18

its

value

the

is

of

in

sulphur even

content into

study

as

of

are

employed

under

that

is

stipulated

included

composition

value

coefficient

was

steels

melts

sulphur

coefficient value

of

corrosion

If

not

f

the

this

conditions

efficiency

the

the

both

unity: of

the

nor

of

steels;

test.

This

stabilized

these

intergranular

efficiency

of

on

for

known

level.

in

stabilization

stabilized

values

valid

value

upon

depends constructed

approaches

according

the

reference

is

steel

decreases individual

the

0.98

low-

paper

effective

that

in

stepped

terms

the of

standard

efficiency

of

coefficients

grades

included

to

this

in

value

susceptible

8169

for

test

in

compare

-

applied

steels;

indicated

were

be

are

value

calculation,

below

03

results

standard

bilization

be

four

to

of

the (the

may

of

found

coefficient

assessed

If

case

composition),

to

steels.

total

efficiency

contents

after

the

the

were

nitrogen

0.98

The

the

and

derived intergranular

in

stabilized

was

in

and

discussed

to

chromium

were to

analysis,

these

stabilization

of

that

steels

were

for

carbon

chemical

these

chemical

applicability

of

&

stainless

steels,

validated

content

eness

the

contents

resistance

of

on

were degree

effective

of

CrNi

their

lationships

the

parameter

lower,

stato

with

standards. are

known, i.e.

0.7. following obtained:

recommendations the

procedure

can

be

made

discussed

in

with the

regard present

to

the

paper

concerning

the

evaluation

intergranular suited

corrosion

for

ditions

use

can

at

be

made

nuity

and

integrity

into

final

for the

to

of

the

the

k.

trimming

composition

and

not

be

the

test

ad-

before the

conti-

processing

of

disturbed

this

to

particularly

Furthermore,

steelmaking would

as

is

steels

since

chemical

corrosion;

product

and

parameter

products

stabilized

steelmaking,

modify

of

of

practicable,

the

intergranular final

resistance

stage

to

steel test

is

the

referring

teeming,

on

of

by

would

making

be

the

the

carried

out

prescribed.

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