Nickel-based alloys - Determination of resistance to intergranular corrosion (ISO 9400:1990)

Includes four methods: iron(III) sulfate - sulfuric acid test, copper - copper-sulfate - sulfuric acid test, hydrochloric acid test and nitric acid test. ISO 9400 defines the term nickel-based alloy. Specifies apparatus, test specimens, procedure and evaluation.

Legierungen auf Nickelbasis - Bestimmung der Beständigkeit gegen interkristalline Korrosion (ISO 9400:1990)

Die vorliegende Internationale Norm legt für Nickelbasislegierungen vier Verfahren zur Bestimmung der Anfälligkeit gegen interkristalline Korrosion fest. Diese Methoden sind nur zur Ermittlung der Empfindlichkeit gegen interkristalline Korrosion unter Laborbedingungen geeignet und eine Übertragbarkeit auf tatsächliche Betriebsbedingungen muß nicht gegeben sein, wenn nicht Betriebs- und Prüfmedium übereinstimmen.

Alliages à base de nickel - Détermination de la résistance à la corrosion intergranulaire (ISO 9400:1990)

La présente Norme internationale prescrit quatre méthodes pour la détermination de la sensibilité des alliages à base de nickel à la corrosion intergranulaire. Ces méthodes ne sont utilisables qu'en laboratoire, et il n'est pas possible d'établir une corrélation directe avec la corrosion intergranulaire en service normal, à moins que le milieu ambiant en service ne soit le même qu'en essai. Les méthodes couvertes sont les suivantes: -- Méthode A: Essai au sulfate de fer(III) et à l'acide sulfurique (section 2). -- Méthode B: Essai au cuivre, au sulfate de cuivre et à l'acide sulfurique à 16 % (section 3). -- Méthode C: Essai à l'acide chlorhydrique (section 4). -- Méthode D: Essai à l'acide nitrique (section 5). La méthode la meilleure à utiliser pour un alliage donné, le choix du traitement de sensibilisation et les critères de réception utilisés pour l'évaluation quelle qu'elle soit, doivent être convenus entre l'acheteur et le vendeur de l'alliage. Les méthodes prescrites dans la présente Norme internationale, à titre indicatif, sont applicables aux alliages à base de nickel employés en milieu corrosif, énumérés dans ISO 6207.

Zlitine na osnovi niklja – Ugotavljanje odpornosti proti interkristalni koroziji (ISO 9400:1990)

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SIST EN ISO 9400:1999

Zlitine na osnovi niklja – Ugotavljanje odpornosti proti interkristalni koroziji (ISO


Nickel-based alloys - Determination of resistance to intergranular corrosion (ISO


Legierungen auf Nickelbasis - Bestimmung der Beständigkeit gegen interkristalline

Korrosion (ISO 9400:1990)

Alliages a base de nickel - Détermination de la résistance a la corrosion intergranulaire

(ISO 9400:1990)
Ta slovenski standard je istoveten z: EN ISO 9400:1995
77.060 Korozija kovin Corrosion of metals
SIST EN ISO 9400:1999 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 9400:1999
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SIST EN ISO 9400:1999
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SIST EN ISO 9400:1999
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SIST EN ISO 9400:1999
First edi tion
----- Pp-__p-I_P-
Nickel-based alloys - Determination of
resistance to intergranular corrosion
Alliages 5 base de nicke1 - D6terniination de la resistance ;i la
in tergranulaire
Reference number
ISO 9400: 199O(E)
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SIST EN ISO 9400:1999
ISO 9400:199O(E)
ISO (the International Organization for Standardization) is a worldwide
federation of national standards bodies (ISO member bodies). The work
of preparing International Standards is normally carried out through ISO
technical committees. Esch member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an lnter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard ISO 9400 was prepared by Technical Committee
ISO/TC 156, Corrosion of mefals and alloys.
Annex A of this International Standard is for information only.
0 ISO 1990

All rights reserved. No part of this publication may be reproduced or utilized in any form

or by any means, electronie or mechanical, including photocopying and microfilm, without

Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
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SIST EN ISO 9400:1999
Nickel-based alloys - Determination of resistance to
intergranular corrosion
Section 1: General
NOTE 1 This definition is consistent with that given in
1.1 Scope
ISO 6372-1123.
This International Standard specifies four methods
for determination of the susceptibility of nickel- 1.3 Apparatus
based alloys to intergranular corrosion.
The recommended apparatus is shown in figure 1.
These methods are for laboratoty testing of suscep-
The cold-finger type of condenser with Standard
tibility only, and a direct correlation with inter-
Erlenmeyer flasks should not be used except for
granular corrosion in actual seivice may not occur
method D.
unless the Service medium is the Same as the test
The following items are required.
The methods covered are as follows:
1.3.1 Four-bulb Allihn or Soxhlet condenser with
45/50 qround glass joint.
- Method A: iron(lll) sulfate - sulfuric acid test
(section 2);
1.3.2 Erlenmeyer flask, capacity 1 dm3, with
45/50 ground glass joint.
- Method B: topper - topper-sulfate - f6 %
sulfuric acid test (section 3);
NOTE 2 The use of round flasks with a heating jacket is
also acceptable.
- Method C: hydrochloric acid test (section 4);
1.3.3 Glass cradle or other equivalent means of
- Method D: nitric acid test (section 5);
specimen support, such as glass hooks or stirrups.
The appropriate method for use with a given alloy,
The cradle should have three or four holes in it, to
the selection of sensitizing treatment, and the ac-
increase circulation of the test Solution around the
ceptance criteria to be used in any evaluation have
specimen (see figure 1).
to be agreed between the buyer and Seller of the
alloy. As a guide, the methods specified in this In-
1.3.4 Boiling Chips to promote uniform boiling and
ternational Standard should be applicable to those
to prevent bumping.
nickel-based alloys used for corrosion Service and
listed in ISO 6207c11.
For method A, these boiling Chips should be made
of pure alundum.
1.3.5 Silicone grease for application to the ground
1.2 Definition
qlass joint of the condenser and flask.
For the purposes of this International Standard, the
A PTFE sleeve for the joint is also acceptable.
following definition applies.
1.3.6 Heating device such as an electrically heated
nickel-based alloy: An alloy which includes nicke1 as
hot-plate, for continuous boiling of the test Solution.
the predominant element.
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SIST EN ISO 9400:1999
ISO 9400:1990(E)
should be tut so that no more than a 13 mm width
1.3.7 Analytical balance capable of weighing to at
of unaffected base metal is included on either side
least the nearest 1 mg (if mass loss is to be deter-
of the weld and heat-affected Zone.
lt is intended to test a specimen representing as
nearly as possible the surface of the material used
1.3.8 Stereoscopic microscope capable of magni-
in Service. Surface finishing should be performed
fication of 5x to 2Ox, with a good light Source, for

examination of the tested specimen (for method 8). only as required to remove foreign material and ob-

tain a Standard, uniform finish to represent the ap-
propriate surface, while maintaining reasonable
specimen size for convenience in testing. Normally,
1.4 Preparation of test specimens
removal of more material than necessary will have

The following requirements for the preparation of little influence on the test results. However, in the

special case of surface carburization (sometimes
test specimens are common to all four test methods.
encountered, for instance, in tubing when
Additional requirements are given, where necess-

ary, in the section describing the particular method. carbonaceous lubricants are employed), it may only

be possible to remove the carburized layer com-
A speci men having a total surface area of 20 cm* to
pletely by heavy grinding or machining. Such treat-
30 (31772 is recomme nded . As-welded specimens
in mill
Dimens imetres
Cooling water out
Allihn condenser
i i
4 bulbs, 45/50 joint
’ \
’ /
\i (
i! k
1 \
\ I
I (
i \
1 \
\ I
\ (
Cooling water in
Use Silicone stopcock grease
or a PTFE sleeve on the
ground glass joint
Erlenmeyer flask (1 dm3)
with 45/50 joint
Glass cradle
Boiling Chips
a) Assembled apparatus b)
Figure 1 - Recommended apparatus
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SIST EN ISO 9400:1999
ISO 9400:1990(E)

ment of non-carburized test specimens is not of the pick .ling bath o n the sp ecimen be te sted Prior

permissible, except in tests undertaken to demon- to the envi ronmental exposur *e.

strate specific surface effects. When samples are tut
by shearing, the deformed metal shall be removed
1.5.2 Spetimens of alloys to be‘ given a
by grinding or machining Prior to testing.
sensitization treatment Prior to testing shall be
placed in a furnace at the required temperature and
Prior to testing, the test spec imens sha II be de-
and shall then be water
for the required time,
ed with a c hlorine-free sol vent a nd ri nsed.
quenched. The use of a sensitization treatment shall
be agreed upon between buyer and seller-.
1.5 Sensitiration of test specimens
1.5.3 Spetimens of alloys that are not given a

1.51 Spetimens to be given a thermal treatment sensitization treatment shall be tested in a condition

Prior to testing shall be clean of carbonaceous ma- simulating end-use conditions. Spetimens from ma-

terial Prior to the thermal treatment. Otherwise, terial that is intended to be welded or heat treated

carburization may invalidate the test results. A light shall be welded or heat treated in nearly the Same

surface grinding or pickling followed by washing and manner as the material will experience in fabri-

rinsing in a non-chlorinated solvent should provide cation or Service. The specific treatment shall be

a clean surface. lt is recommended that the effect agreed upon between buyer and Seller.

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SIST EN ISO 9400:1999
ISO 9400:1990(E)
Section 2: Method A - Iron(lll) sulfate - Suifuric acid test
taneously. The number is limited only by the number
2.1 Scope
of glass cradles that tan be fitted into the flask
(usually three or four). In no case shall different al-
This section describes the procedure for conducting
loys be tested together. Esch specimen shall be in
the boiling iron(lll) sulfate - sulfuric acid test to de-
a separate cradle so that the specimens do not
termine the susceptibility of nickel-based alloys to
intergranular attack.
Mark the liquid level on the flask with a heat-
resistant marker to provide a check on vapour loss.
2.2 Iron(lll) sulfate - sulfuric acid test
If there is an appreciable Change in the level, repeat
the test with fresh Solution and a new specimen.
Prepare 600 cm3 of test Solution as follows.
Continue immersion of the specimen for a period of
24 h or 120 h, then remove the specimen, rinse in
Measure 400 cm3 of distilled water into a 500 cm3
water and acetone, and dry. For alloys containing
graduated cylinder and pour into the Erlenmeyer
less than 18 % chromium the exposure time is typi-
flask (1.3.2).
cally 24 h. For alloys containing more than 18 %
chromium the exposure time is 120 h.
Measure 236 cm3 of reagent grade 95 to
98 % (r7z/m) sulfuric acid into a 250 cm3 graduated
Weigh the specirnen and subtract the mass from the
cylinder. Add the acid slowly to the watet- in the
original mass.
Erlenmeyer flask to avoid boiling by the heat
evolved. (Loss of vapour results in an increase in
the acid concentration.)
3 No intermediate weighings are usually necessary. The
Weigh 25 g of reagent grade iron(lll) sulfate
tests tan be run without interruption; however, if prelimi-
nonahydrate [ Fe,(SO,),.SH,O, containing about
nary results are desired, the specimen tan be removed
and add it to the sulfuric acid sol- at any time for weighing.
75 % Fe,(SO,), 1,
ution. A trip balance may be used.
4 Not hanges in the test Solution are necessary during
the test period.
Drop several boiling Chips (1.3.4) into the flask.
5 Additional iron(lll) sulfate inhibitor may have to be
Lubricate the ground glass joint with Silicone grease
added during the test if the corrosion rate is unusually
high, as evidenced by a Change in the colour of the sol-
ution. More iron(lll) sulfate has to be added if the total
Fit the flask to the condenser (1.3.1) and circulate
mass loss of all specimens exceeds 2 g [during the test,
cooling water.
iron(lll) sulfate is consumed at a rate of approximateiy
10 g for each 1 g of dissolved metal].
Boil the Solution until all the iron(lll) sulfate is dis-
6 During testing, there is some deposition of iron oxides
on the upper part of the Erlenmeyer flask. This tan be
readily removed, after completion of the test, by boiling
2.3 Preparation of test specimens
a 10 % (H@I) Solution of hydrochloric acid in the flask.
See clause 1.4.
2.5 Evaluation
2.4 Procedure
Measure the dimensions of the specimen to the
2.5.1 The effect of the test Solution on the material
nearest 0,5 mm, including the inner dimensions of
tan be measured by determining the loss of mass
any holes, and calculate the total exposed surface
of the specimen. Calculate the corrosion rate as fol-
Degrease the specimen using a non-chlorinated k x Am
corrosion rate = Y------
solvent, dry and then weigh to the nearest 1 mg. Axfxp
Place the specimen in a glass cradle (1.3.3) and im-
merse it in boiling test Solution (clause 2.2).
k is a constant (see note 7);
Testing of a Single specimen in a flask is preferred.
is the exposure time, in hours;
However, several specimens may be tested simul-
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SIST EN ISO 9400:1999
ISO 9400:1990(E)
8,76 x 107
micrometres per year (rlm/y)
n is the exposed area, in Square centi-
metres, of the sp ecime
picometres per second (pmls) 2,78 x 106
is the mass loss, in grams;
2.5.2 The presence of intergranular attack is usu-
is the density, in gram s per cubic centi-
ally determined by comparing the calculated corro-
m etre, of the spe cimen
sion rate to that for properly annealed material.
Even in the absence of intergranular attack, the rate
NOTE 7 Using the above units for t, A, Am and p, the
of general or grain-face corrosion of properly
corrosion rate tan be calculated in a variety of units using
annealed material will vary from one alloy to an-
the appropriate value of k:
other. The corrosion rate considered acceptable
shall be determined between buyer and Seller.
Corrosion rate units desired Value of k to be used
mils [milliinches] per year (mpy) 3,45 x 106
As an alternative or in addition to calculating
a corrosion rate from mass loss data,
inches per year (ipy) 3,45 x 103
metallographic examination may be used to evalu-
inches per month (ipm) 2,85 x 102
ate the degree of intergranular attack. The depth of
attack considered acceptable shall be determined
millimetres per year (mmly) 8,76 x 104
between buyer

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