SIST EN ISO 204:2011

SLOVENSKI oSIST prEN ISO 204:2005

PREDSTANDARD
november 2005
Kovinski materiali – Preskušanje nesoosnega lezenja pri nategu – Metoda
preskušanja (ISO/DIS 204:2005)
Metallic materials - Uniaxial creep testing in tension - Method of test (ISO/DIS
204:2005)
ICS 77.040.10 Referenčna številka
oSIST prEN ISO 204:2005(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

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EUROPEAN STANDARD
DRAFT
prEN ISO 204
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2005
ICS

English Version
Metallic materials - Uniaxial creep testing in tension - Method of
test (ISO/DIS 204:2005)
Matériaux métalliques - Essai de fluage uniaxial en traction
- Méthode d'essai (ISO/DIS 204:2005)
This draft European Standard is submitted to CEN members for parallel enquiry. It has been drawn up by the Technical Committee
ECISS/TC 1.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same
status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN ISO 204:2005: E
worldwide for CEN national Members.

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prEN ISO 204:2005 (E)




Foreword

This document (prEN ISO 204:2005) has been prepared by Technical Committee ISO/TC 164
"Mechanical testing of metals" in collaboration with Technical Committee ECISS/TC 1 "Steel -
Mechanical testing", the secretariat of which is held by AFNOR.

This document is currently submitted to the parallel Enquiry.

Endorsement notice

The text of ISO/DIS 204:2005 has been approved by CEN as prEN ISO 204:2005 without any
modifications.

2

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DRAFT INTERNATIONAL STANDARD ISO/DIS 204
ISO/TC 164/SC 1 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2005-09-08 2006-02-08
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Metallic materials — Uniaxial creep testing in tension — Method
of test
Matériaux métalliques — Essai de fluage uniaxial en traction — Méthode d'essai
[Revision of first edition (ISO 204:1997)]
ICS 77.040.10

ISO/CEN PARALLEL ENQUIRY
The CEN Secretary-General has advised the ISO Secretary-General that this ISO/DIS covers a subject
of interest to European standardization. In accordance with the ISO-lead mode of collaboration as
defined in the Vienna Agreement, consultation on this ISO/DIS has the same effect for CEN
members as would a CEN enquiry on a draft European Standard. Should this draft be accepted, a
final draft, established on the basis of comments received, will be submitted to a parallel two-month FDIS
vote in ISO and formal vote in CEN.
In accordance with the provisions of Council Resolution 15/1993 this document is circulated in
the English language only.
Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est distribué
en version anglaise seulement.
To expedite distribution, this document is circulated as received from the committee secretariat.
ISO Central Secretariat work of editing and text composition will be undertaken at publication
stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
© International Organization for Standardization, 2005

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ISO/DIS 204
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the
unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
Copyright notice
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under the applicable laws of the user's country, neither this ISO draft nor any extract from it may be
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Violators may be prosecuted.
©
ii ISO 2005 – All rights reserved

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ISO/DIS 204
Contents Page
Foreword .v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols and designations.4
5 Principle.6
6 Apparatus.6
6.1 Testing machine.6
6.2 Elongation measuring device .6
6.3 Heating device.7
6.3.1 Permissible temperature deviations.7
6.3.2 Temperature measurement.8
6.3.3 Calibration of the thermocouples and temperature measuring system.8
7 Test pieces.9
7.1 Shape and dimensions.9
7.2 Preparation.10
7.3 Determination of the original cross-sectional area .11
7.4 Marking of the original gauge length (L ).11
o
7.5 Determination of the reference length (L ).11
r
8 Test procedure.12
8.1 Heating of the test piece.12
8.2 Application of the test force.12
8.3 Test interruptions.12
8.3.1 General.12
8.3.2 Multiple test piece machine with several test pieces in line.12
8.3.3 Accidental interruption of the test.12
8.4 Recording of temperature and elongation.12
8.4.1 Temperature.12
8.4.2 Elongation.12
8.4.3 Elongation time diagram.13
9 Determination of results .13
10 Test validity.13
11 Accuracy of the results.13
11.1 Expression of the results.13
11.2 Final uncertainty.14
12 Test report.14
Annex A (informative) Information concerning different types of thermocouples .5
Annex B (informative) Information concerning methods of calibration of thermocouples
(see Bibliography) .6
Annex C (informative) Creep Testing using test pieces with V or blunt circumferential notches .7
C.4 References.10
Annex D (informative)  Method of estimating the uncertainty of the measurement in accordance
with the ISO "Guide to the expression of uncertainty in measurement" (GUM).11
D.1 Introduction.11
© ISO 2005 – All rights reserved iii

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ISO/DIS 204
D.2 Statements of uncertainty.11
D.2.1 Background.11
D.2.2 Statement of uncertainty : Creep testing .13
D.3 A reference material for creep testing.14
D.3.1 General.14
D.3.2 Using the CRM 425 for assessing uncertainty.14
Annex E (informative) Normative, references and symbols for strength values.17
Preamble.17
E.1 Normative references and symbols for strength values.17
E.1.1 Strain .17
E.1.2 Creep rupture strength .17
E.1.3 Stress-to-specific-plastic-strain.17
E.2 Specimens.18
E.2.1 Shape and dimension of smooth specimens .18
E.2.2 Shape and dimension of notched specimens .18
E.3 Evaluation .20
E.3.1 Logarithmic creep diagram .20
E.3.2 Creep rupture diagram.2
E.3.3 Creep rupture elongation diagram .2
E.3.4 Creep diagram with linear scales .2
E.3.5 Extrapolation.2
E.3.6 Test report, recommended additional information.3
Bibliography .6

iv © ISO 2005 – All rights reserved

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ISO/DIS 204
Foreword
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. Each 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, governmental 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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 204 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 1, and by Technical Committee ECISS/TC1, Steel testing - Mechanical testing in collaboration.
This second edition cancels and replaces the first edition (EN ISO 204:1997).

© ISO 2005 – All rights reserved v

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DRAFT INTERNATIONAL STANDARD ISO/DIS 204

Metallic materials — Uniaxial creep testing in tension — Method of
test
1 Scope

This International Standard specifies the method for the uninterrupted and interrupted creep tests and defines the
properties of metallic materials which can be determined from these tests, in particular the creep elongation and the
time of creep rupture, at a specified temperature.
NOTE The stress rupture test is also covered by this standard, as is the testing of notched test pieces.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only
the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
ISO 286-2, ISO system of limits and fits — Part 2: Tables of standard tolerances grades and limit deviations for holes
and shafts.
ISO 783-1999, Metallic materials — Tensile testing method at elevated temperature
ISO 7500-2, Metallic materials — Verification of static uniaxial testing machines — Part 2: Tensile creep testing
machines — Verification of the force applied.
ISO 9513, Metallic materials — Calibration of extensometers used in uniaxial testing.
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply:
3.1
reference length (L )
r
base length used for the calculation of elongation
NOTE A method to calculate this value is given in 7.5.
Distinction is made between :
3.1.1
original reference length (L )
ro
reference length determined at ambient temperature before the test
3.1.2
final reference length (L )
ru
reference length determined at ambient temperature after rupture, with the pieces carefully fitted back together with
their axes in a straight line
© ISO 2005 – All rights reserved 1

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ISO/DIS 204
3.2
original gauge length (L )
o
length between gauge length marks on the test piece measured at ambient temperature before the test
3.3
final gauge length after rupture (L )
u
length between gauge length marks on the test piece measured after rupture, at ambient temperature, with the pieces
carefully fitted back together with their axes in a straight line
3.4
parallel length (L )
c
length of the parallel reduced section of the test piece
3.5
extensometer gauge length (L )
e
distance between the measuring points of extensometer
NOTE In some cases, L = L .
e o
3.6
original cross-sectional area (S )
o
cross-sectional area of the parallel length as determined at ambient temperature prior to testing
3.7
minimum cross-sectional area after rupture (S )
u
minimum cross-sectional area of the parallel length as determined at ambient temperature after rupture, with the
pieces carefully fitted back together with their axes in a straight line
3.8
initial stress (σ )
o
applied force divided by the original cross-sectional area (S ) of the test piece
o
3.9
elongation (ΔL )
r
increase of the reference length (L ), see 6.2
r
3.10
percentage elongation (A)
elongation expressed as a percentage of the original reference length L , see Figure 1
ro
NOTE In the case of the terms for elongation in 3.10 (except A , in 3.10.6), the symbol “ε ” may replace “A”.
u
However, when “ε" is used, the following convention should apply :
- ε % = percentage strain/elongation ;
- ε = absolute strain.
3.10.1
percentage initial plastic elongation (A )
i
non-proportional increase of the original reference length L due to the application of the test force
ro
3.10.2
percentage creep elongation (A )
f
increase in reference length at time t (ΔL ) at a specified temperature expressed as a percentage of the original
rt
reference length (L ):
ro
∆L
rt
A = x100 (1)
f
L
ro

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ISO/DIS 204
NOTE 1 A may have the specified temperature (T) in Celsius degrees as superscript and s the initial stress (σ ) in megapascals
f o
1)
and time t (in hours) as subscript.
NOTE 2 By convention the beginning of creep elongation measurement is the time at which the initial stress (σ ) is applied to
o
the test piece (see Figure 1).
3.10.3
percentage plastic elongation (A )
p
non-proportional increase of the original reference length (L ) at time t :
ro
A = A + A (2)
p i f
3.10.4
percentage anelastic elongation (A )
k
non-proportional decrease of the original reference length (L ) at time t due to unloading
ro
3.10.5
percentage permanent elongation (A )
per
total increase of the original reference length (L ) at time t determined after unloading :
ro
A = A – A (3)
per p k
3.10.6
percentage elongation after creep rupture (A )
u
permanent increase of the original reference length (L ) after rupture (L - L ) expressed as a percentage of the
ro ru ro
original reference length (L ) :
ro
L −L
ru ro
A = x100 (4)
u
L
ro
NOTE A may have the specified temperature (T) in Celsius degrees as superscript and the initial stress (σ ) in megapascals
u o
as subscript.
3.11
percentage reduction of area after creep rupture (Z )
u
maximum change in cross-sectional area measured after rupture (S - S ) expressed as a percentage of the original
o u
cross-sectional area (S ) :
o
S −S
o u
Z = x 100 (5)
u
S
o
NOTE Z may have the specified temperature (T) in Celsius degrees as superscript and the initial stress (σ ) in megapascals .
u o
3.12
creep elongation time (t )
fx
time required for a strain test piece to obtain a specified percentage creep elongation (x) at the specified temperature
(T) and the initial stress (σ ).
o
EXAMPLE t
f0,2
3.13
plastic elongation time (t )
px
time required to obtain a specified percentage plastic deformation (x) at the specified temperature (T) and the initial
stress (σ ).
o

2
1
) 1 MPa = 1 N/mm .
© ISO 2005 – All rights reserved 3

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ISO/DIS 204
3.14
creep rupture time (t )
u
time to rupture for a test piece maintained at the specified temperature (T) and the initial stress (σ ).
o
NOTE The symbol t may have as superscript the specified temperature (T) in Celsius degrees and as subscript the initial
u
stress (σ ) in megapascals
o
3.15
Single test piece machine
a testing machine that permits straining of a single test piece
3.16
multiple test piece machine
a testing machine that permits straining of more than one test piece simultaneously at the same temperature
4 Symbols and designations
The symbols and corresponding designations are given in Table 1.
Table 1 — Symbols and designations
b
Reference Symbol Unit Designation
a
number
1 D mm Diameter of the cross-section of the parallel length of a cylindrical test
piece
2 B mm Width of the cross-section of the parallel length of a test piece of square
or rectangular cross-section
3 L mm Reference length
r
4 A mm Thickness of a test piece of square or rectangular cross-section
- L mm Original reference length
ro
- L mm Final reference length
ru
- mm Elongation
ΔL
r
ΔL mm Increase in reference length at time t
rt
5 L mm Original gauge length
o
- L mm Final gauge length after rupture
u
L
6 mm Parallel length
c
7 L mm Extensometer gauge length
e
8 R mm Transition radius
2
9 S mm Original cross-sectional area of the parallel length
o
2
S
- mm Minimum cross-sectional area after rupture
u
10 σ MPa Initial stress
o
continued

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ISO/DIS 204
Table 1 — Symbols and designations (continued)
b)
Reference Symbol Unit Designation
a)
number
c
11 A % Percentage elastic elongation
e
c
12 A % Percentage initial plastic elongation
i
c
13 A % Percentage anelastic elongation
k
c
14 A % Percentage plastic elongation
p
c
15 A % Percentage permanent elongation
per
c
16 A % Percentage creep elongation :
f
∆L
rt
A = x100
f
L
ro
NOTE As an example, the symbol may be completed as follows :
375
A : percentage creep elongation with an initial stress of
f
50 / 5000
50 MPa after 5 000 h at the specified temperature of 375 °C.
c
23 A % Percentage elongation after creep rupture :
u
L −L
ru ro
A = x100
u
L
ro
NOTE As an example, the symbol may be completed as follows :
375
A : percentage elongation after creep rupture with an initial stress
u
50
of 50 MPa at the specified temperature of 375 °C.
- Z % Percentage reduction of area after creep rupture :
u
S −S
o u
Z = x100
u
S
o
NOTE As an example, the symbol may be completed as follows :
375
Z : percentage reduction of area after creep rupture with an initial
u
50
stress of 50 MPa at the specified temperature of 375 °C.
t
h Creep elongation time
fx
t h Plastic elongation time
px
24 t h Creep rupture time
u
NOTE As an example, the symbol may be completed as follows :
375
t : creep rupture time with an initial stress of 50 MPa at the
u
50
specified temperature of 375 °C.
- t h Creep rupture time of a notched test piece
ue
continued
© ISO 2005 – All rights reserved 5

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ISO/DIS 204
Table 1 — Symbols and designations (end)
b)
Reference Symbol Unit Designation
a)
number
- T °C Specified temperature
T
- °C Indicated temperature
i
- x % Specified percentage creep or plastic elongation
- n Creep exponent
a
See Figures 1 and 2.
b
The main subscripts (r, o and u) of the symbols are used as follows :
r corresponds to reference ;
o corresponds to original ;
u corresponds to ultimate (after rupture).
c
See note in 3.10.
5 Principle
The test consists of heating a test piece to the specified temperature and of straining the test piece by means of a
constant tensile force or constant tensile stress (see note) applied along its longitudinal axis for a period of time to
obtain any of the following :-
 a specified creep elongation (uninterrupted test),
 values of permanent elongation at suitable intervals throughout the test(interrupted test),
 The creep rupture time (uninterrupted and interrupted test)
NOTE "Constant stress" means that the ratio of the force to the instantaneous cross-section remains constant throughout the
test. The results obtained with constant stress are generally different from those with constant force.
6 Apparatus
6.1 Testing machine
The testing machine shall apply a force along the axis of the test piece while keeping inadvertent bending or torsion of
the test piece to a minimum.
NOTE 1 The force should be applied to the test piece without shock.
NOTE 2 The machine should be isolated from external vibration and shock. The machine should be equipped, with a device
which minimizes shock when the test piece ruptures.
The machine shall be verified and shall meet the requirements of at least class 1 in ISO 7500-2.
6.2 Elongation measuring device
In uninterrupted tests, the elongation shall be measured using an extensometer, which meets the perf
...

SLOVENSKI STANDARD
oSIST prEN ISO 204:2008
01-marec-2008
Kovinski materiali - Preskušanje nesoosnega lezenja pri nategu - Metoda
preskušanja (ISO/DIS 204:2007)
Metallic materials - Uniaxial creep testing in tension - Method of test (ISO/DIS 204:2007)
Metallische Werkstoffe - Einachsiger Zeitstandversuch unter Zugbeanspruchung -
Prüfverfahren (ISO/DIS 204:2007)
Matériaux métalliques - Essai de fluage uniaxial en traction - Méthode d'essai (ISO/DIS
204:2007)
Ta slovenski standard je istoveten z: prEN ISO 204
ICS:
77.040.10
oSIST prEN ISO 204:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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EUROPEAN STANDARD
DRAFT
prEN ISO 204
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2007
ICS 77.040.10

English Version
Metallic materials - Uniaxial creep testing in tension - Method of
test (ISO/DIS 204:2007)
Matériaux métalliques - Essai de fluage uniaxial en traction Metallische Werkstoffe - Einachsiger Zeitstandversuch
- Méthode d'essai (ISO/DIS 204:2007) unter Zugbeanspruchung - Prüfverfahren (ISO/DIS
204:2007)
This draft European Standard is submitted to CEN members for second parallel enquiry. It has been drawn up by the Technical Committee
ECISS/TC 1.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN ISO 204:2007: E
worldwide for CEN national Members.

---------------------- Page: 2 ----------------------
prEN ISO 204:2007 (E)
Contents Page
Foreword.3

2

---------------------- Page: 3 ----------------------
prEN ISO 204:2007 (E)
Foreword
This document (prEN ISO 204:2007) has been prepared by Technical Committee ISO/TC 164 "Mechanical
testing of metals" in collaboration with Technical Committee ECISS/TC 1 “Steel - Mechanical testing” the
secretariat of which is held by AFNOR.
This document is currently submitted to the second parallel Enquiry.
Endorsement notice
The text of ISO/DIS 204:2007 has been approved by CEN as a prEN ISO 204:2007 without any modification.

3

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DRAFT INTERNATIONAL STANDARD ISO/DIS 204.2
ISO/TC 164/SC 1 Secretariat: AFNOR
Voting begins on: Voting terminates on:
2007-11-29 2008-01-29
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Metallic materials — Uniaxial creep testing in tension — Method
of test
Matériaux métalliques — Essai de fluage uniaxial en traction — Méthode d'essai
[Revision of first edition (ISO 204:1997)]
ICS 77.040.10

ISO/CEN PARALLEL ENQUIRY
The CEN Secretary-General has advised the ISO Secretary-General that this ISO/DIS covers a subject
of interest to European standardization. In accordance with the ISO-lead mode of collaboration as
defined in the Vienna Agreement, consultation on this ISO/DIS has the same effect for CEN
members as would a CEN enquiry on a draft European Standard. Should this draft be accepted, a
final draft, established on the basis of comments received, will be submitted to a parallel two-month FDIS
vote in ISO and formal vote in CEN.
To expedite distribution, this document is circulated as received from the committee secretariat.
ISO Central Secretariat work of editing and text composition will be undertaken at publication
stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
©
International Organization for Standardization, 2007

---------------------- Page: 5 ----------------------
ISO/DIS 204.2
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
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ISO/DIS 204.2
Contents Page
Foreword .v
Introduction.vi
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols and designations.4
5 Principle.6
6 Apparatus.6
6.1 Testing machine .6
6.2 Elongation measuring device .7
6.3 Heating device .7
6.3.1 Permissible temperature deviations.7
6.3.2 Temperature measurement .8
6.3.3 Calibration of the thermocouples and temperature measuring system.9
7 Test pieces .10
7.1 Shape and dimensions .10
7.2 Preparation.10
7.3 Determination of the original cross-sectional area .11
7.4 Marking of the original gauge length (L ).11
o
7.5 Determination of the reference length (L ).12
r
8 Test procedure.12
8.1 Heating of the test piece.12
8.2 Application of the test force.12
8.3 Test interruptions.13
8.3.1 General .13
8.3.2 Multiple test piece machine with several test pieces in line.13
8.3.3 Accidental interruption of the test.13
8.4 Recording of temperature and elongation.13
8.4.1 Temperature.13
8.4.2 Elongation .13
8.4.3 Elongation time diagram.14
9 Determination of results .14
10 Test validity.14
11 Accuracy of the results.14
11.1 Expression of the results .14
11.2 Final uncertainty.14
12 Test report.15
Annex A (informative) Information concerning different types of thermocouples .21
Annex B (informative) Information concerning methods of calibration of thermocouples .22
Annex C (informative) Creep testing using test pieces with Vee or blunt circumferential notches .23
C.1 General.23
C.2 Vee notched test pieces.23
C.3 Blunt Circumferential Notches.24
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ISO/DIS 204.2
Annex D (informative) Method of estimating the uncertainty of the measurement in accordance
with the ISO "Guide to the expression of uncertainty in measurement" (GUM). 26
D.1 General. 26
D.1.1 Test Conditions. 26
D.1.2 Test Results. 26
D.2 General. 26
D.3 Statements of uncertainty. 27
D.3.1 Background. 27
D.3.2 Statement of uncertainty: creep testing. 29
D.4 A reference material for creep testing. 30
D.4.1 General. 30
D.4.2 Using the CRM 425 for assessing uncertainty . 31
D.5 Uncertainties in creep testing of single crystal nickel-base superalloy at 1100 °C. 31
Annex E (informative) Representation of results and graphical extrapolation. 33
E.1 General. 33
E.2 Symbols for strength values and their calculation . 33
E.2.1 Strain. 33
E.2.2 Creep rupture strength. 33
E.2.3 Stress-to-specific-plastic-strain. 33
E.3 Specimens. 33
E.3.1 Shape and dimension of smooth specimens . 33
E.3.2 Shape and dimension of notched specimens . 34
E.4 Evaluation. 37
E.4.1 General. 37
E.4.2 Logarithmic creep diagram. 38
E.4.3 Creep rupture diagram . 38
E.4.4 Creep rupture elongation diagram. 39
E.4.5 Creep diagram with linear scales. 39
E.5 Extrapolation. 39
E.5.1 Graphical extrapolation and creep rupture diagram. 39
E.5.2 Extrapolation by means of time-temperature-parameters. 39
E.6 Test report, recommended additional information . 40
Bibliography. 43

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ISO/DIS 204.2
Foreword
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. Each 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, governmental 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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 204 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 1, and by Technical Committee ECISS/TC ECISS/TC 1, Steel testing - Mechanical testing in
collaboration.
This second edition cancels and replaces the first edition (EN ISO 204:1997), that has been technically
revised.

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ISO/DIS 204.2
Introduction
This Standard is an extensive revision of the first edition of EN ISO 204:1997 and incorporates many
recommendations developed through the European Creep Collaborative Committee (ECCC).
New informative Annexes have been added concerning temperature measurement using thermocouples and
their calibration, creep testing test pieces with circumferential Vee and blunt (Bridgman) notches, estimation of
measurement uncertainty and methods of extrapolation of creep rupture life.
NOTE Information is sought relating to the influence of off-axis loading or bending on the creep properties of various
materials. Consideration will be given at the next revision of this Standard as to whether the maximum amount bending
should be specified and an appropriate calibration procedure be recommended. The decision will need to be based on the
availability of quantitative data.
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DRAFT INTERNATIONAL STANDARD ISO/DIS 204.2

Metallic materials — Uniaxial creep testing in tension — Method
of test
1 Scope

This International Standard specifies the method for the uninterrupted and interrupted creep tests and defines
the properties of metallic materials which can be determined from these tests, in particular the creep
elongation and the time of creep rupture, at a specified temperature.
The stress rupture test is also covered by this standard, as is the testing of notched test pieces.
NOTE In stress rupture testing elongation is not generally recorded during the test, only the time to failure under a
given load, or to note that a predetermined time was exceeded under a given load.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 286-2, ISO system of limits and fits — Part 2: Table of standard tolerances grades and limit deviations for
holes and shafts. – check the number for this standard.
ISO 783, Metallic materials — Tensile testing method at elevated temperature.
ISO 7500-2, Metallic materials — Verification of static uniaxial testing machines — Part 2: Tensile creep
testing machines — Verification of the force applied.
ISO 9513, Metallic materials — Calibration of extensometers used in uniaxial testing.
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply:
3.1
reference length (L )
r
base length used for the calculation of elongation
NOTE A method to calculate this value is given in 7.5.
3.2
original reference length (L )
ro
reference length determined at ambient temperature before the test
3.3
final reference length (L )
ru
reference length determined at ambient temperature after rupture, with the pieces carefully fitted back
together with their axes in a straight line
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ISO/DIS 204.2
3.4
original gauge length (L )
o
length between gauge length marks on the test piece measured at ambient temperature before the test
3.5
final gauge length after rupture (L )
u
length between gauge length marks on the test piece measured after rupture, at ambient temperature, with
the pieces carefully fitted back together with their axes in a straight line
3.6
parallel length (L )
c
length of the parallel reduced section of the test piece
3.7
extensometer gauge length (L )
e
distance between the measuring points of extensometer
NOTE In some cases, L = L .
e o
3.8
original cross-sectional area (S )
o
cross-sectional area of the parallel length as determined at ambient temperature prior to testing
3.9
minimum cross-sectional area after rupture (S )
u
minimum cross-sectional area of the parallel length as determined at ambient temperature after rupture, with
the pieces carefully fitted back together with their axes in a straight line
3.10
initial stress (σ )
o
applied force divided by the original cross-sectional area (S ) of the test piece
o
3.11
elongation (∆L )
r
increase of the reference length (L )
r
NOTE see 6.2
3.12
percentage elongation (A)
elongation expressed as a percentage of the original reference length L , see Figure 1
ro
NOTE In the case of the terms for elongation in 3.10 (except A , in 3.10.6), the symbol “ε ” may replace “A”.
u
However, when “ε" is used, the following convention should apply:
ε % = percentage strain/elongation;
ε = absolute strain.
3.13
percentage initial plastic elongation (A )
i
non-proportional increase of the original reference length L due to the application of the test force
ro
3.14
percentage creep elongation (A )
f
increase in reference length at time t (∆L ) at a specified temperature expressed as a percentage of the
rt
original reference length (L ):
ro
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ISO/DIS 204.2
∆L
rt
A = × 100
f
L
ro
NOTE 1 A may have the specified temperature (T) in Celsius degrees as superscript and s the initial stress (σ ) in
f o
1)
megapascals and time t (in hours) as subscript.
NOTE 2 By convention the beginning of creep elongation measurement is the time at which the initial stress (σ ) is
o
applied to the test piece (see Figure 1).
3.15
percentage plastic elongation (A )
p
non proportional increase of the original reference length (L ) at time t:
ro
A = A + A
p i f
3.16
percentage anelastic elongation (A )
k
non-proportional decrease of the original reference length (L ) at time t due to unloading
ro
3.17
percentage permanent elongation (A )
per
total increase of the original reference length (L ) at time t determined after unloading:
ro
A = A – A
per p k
3.17
percentage elongation after creep rupture (A )
u
permanent increase of the original reference length (L ) after rupture (L – L ) expressed as a percentage of
ro ru ro
the original reference length (L ):
ro
L −L
ru ro
A = × 100
u
L
ro
NOTE A may have the specified temperature (T) in Celsius degrees as superscript and the initial stress (σ ) in
u o
)
megapascals as subscript.
3.18
percentage reduction of area after creep rupture (Z )
u
maximum change in cross-sectional area measured after rupture (S – S ) expressed as a percentage of the
o u
original cross-sectional area (S ):
o
S −S
o u
Z = ×100
u
S
o
NOTE Z may have the specified temperature (T) in Celsius degrees as superscript and the initial stress (σ ) in
u o

megapascals
3.19
creep elongation time (t )
x
time required for a strain test piece to obtain a specified percentage creep elongation (x) at the specified
temperature (T) and the initial stress (σ )
o
EXAMPLE t
0,2

2
1) 1 MPa = 1 N/mm .
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ISO/DIS 204.2
3.20
plastic elongation time (t )
px
time required to obtain a specified percentage plastic deformation (x) at the specified temperature (T) and the
initial stress (σ )
o
3.21
creep rupture time (t )
u
time to rupture for a test piece maintained at the specified temperature (T) and the initial stress (σ )
o
NOTE The symbol t may have as superscript the specified temperature (T) in Celsius degrees and as subscript the
u
initial stress (σ ) in megapascals.
o
3.22
single test piece machine
testing machine that permits straining of a single test piece
3.23
multiple test piece machine
testing machine that permits straining of more than one test piece simultaneously at the same temperature
4 Symbols and designations
The symbols and corresponding designations are given in Table 1.
Table 1 — Symbols and designations
Reference
b
a Symbol Unit Designation
number
1 D mm Diameter of the cross-section of the parallel length of a cylindrical test
piece
D mm Diameter of gauge length containing a notch
n
d mm Diameter of gauge length without a notch in a combined notched / un-
notched test piece, see Figure C1.
d mm Diameter across root of circumferential notch. For combined notched /
n
un-notched test piece d = d
n
2 b mm Width of the cross-section of the parallel length of a test piece of square
or rectangular cross-section
3 L mm Reference length
r
4 a mm Thickness of a test piece of square or rectangular cross-section
- L mm Original reference length
ro
- L mm Final reference length
ru
- mm Elongation
∆L
r
  (continued)
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ISO/DIS 204.2
Table 1 (continued)
Reference b
Symbol Unit Designation
a
number
Increase in reference length at time t
∆L mm
rt
5 L mm Original gauge length
o
L
n mm Parallel gauge length containing an notch
- L mm Final gauge length after rupture
u
6 L mm Parallel length
c
7 L mm Extensometer gauge length
e
R
8 mm Transition radius
r mm Notch root radius
n
2
9 S mm Original cross-sectional
...