Metallic materials - Uniaxial creep testing in tension - Method of test (ISO 204:2018)

This document specifies the methods for
a)    uninterrupted creep tests with continuous monitoring of extension,
b)    interrupted creep tests with periodic measurement of elongation,
c)    stress rupture tests where normally only the time to fracture is measured,
d)    a test to verify that a predetermined time can be exceeded under a given force, with the elongation or extension not necessarily being reported.
NOTE       A creep test can be continued until fracture has occurred or it can be stopped before fracture.

Metallische Werkstoffe - Einachsiger Zeitstandversuch unter Zugbeanspruchung - Prüfverfahren (ISO 204:2018)

Matériaux métalliques - Essai de fluage uniaxial en traction - Méthode d'essai (ISO 204:2018)

Le présent document spécifie les méthodes pour:
a)    les essais de fluage ininterrompu avec surveillance continue de l'extension,
b)    les essais de fluage interrompus avec mesurage périodique de l'allongement,
c)    les essais de rupture sous contrainte lorsque seul le temps jusqu'à la rupture est normalement mesuré,
d)    un essai pour vérifier qu'un temps prédéterminé peut être dépassé sous une force donnée, sans que l'allongement ou l'extension n'ait été nécessairement rapporté.
NOTE       Une essai de fluage peut se poursuivre jusqu'à la rupture effective ou peut être arrêté avant la rupture.

Kovinski materiali - Preskušanje nesoosnega lezenja pri nategu - Metoda preskušanja (ISO 204:2018)

Ta dokument določa metode za:
a) neprekinjene preskuse lezenja z neprekinjenim spremljanjem razširitve,
b) prekinjene preskuse lezenja s periodičnimi meritvami raztezka,
c) preskuse zloma zaradi obremenitve, pri katerih se običajno meri samo čas do preloma,
d) preskus za potrditev, da je mogoče pri dani sili preseči predhodno določeni čas, pri čemer se ne poroča nujno o raztezku ali razširitvi.
OPOMBA: Preskus lezenja je mogoče nadaljevati, dokler ne pride do preloma, mogoče pa ga je tudi ustaviti pred prelomom.

General Information

Status
Published
Publication Date
09-Oct-2018
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
10-Oct-2018
Completion Date
10-Oct-2018

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SLOVENSKI STANDARD
SIST EN ISO 204:2018
01-december-2018
1DGRPHãþD
SIST EN ISO 204:2011
Kovinski materiali - Preskušanje nesoosnega lezenja pri nategu - Metoda
preskušanja (ISO 204:2018)

Metallic materials - Uniaxial creep testing in tension - Method of test (ISO 204:2018)

Metallische Werkstoffe - Einachsiger Zeitstandversuch unter Zugbeanspruchung -
Prüfverfahren (ISO 204:2018)

Matériaux métalliques - Essai de fluage uniaxial en traction - Méthode d'essai (ISO

204:2018)
Ta slovenski standard je istoveten z: EN ISO 204:2018
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
SIST EN ISO 204:2018 en,fr,de

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

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SIST EN ISO 204:2018
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SIST EN ISO 204:2018
EN ISO 204
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2018
EUROPÄISCHE NORM
ICS 77.040.10 Supersedes EN ISO 204:2009
English Version
Metallic materials - Uniaxial creep testing in tension -
Method of test (ISO 204:2018)

Matériaux métalliques - Essai de fluage uniaxial en Metallische Werkstoffe - Einachsiger Zeitstandversuch

traction - Méthode d'essai (ISO 204:2018) unter Zugbeanspruchung - Prüfverfahren (ISO

204:2018)
This European Standard was approved by CEN on 12 August 2018.

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. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists 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-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 204:2018 E

worldwide for CEN national Members.
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SIST EN ISO 204:2018
EN ISO 204:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 204:2018
EN ISO 204:2018 (E)
European foreword

This document (EN ISO 204:2018) has been prepared by Technical Committee ISO/TC 164 "Mechanical

testing of metals" in collaboration with Technical Committee ECISS/TC 101 “Test methods for steel

(other than chemical analysis)” the secretariat of which is held by AFNOR.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by April 2019, and conflicting national standards shall be

withdrawn at the latest by April 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 204:2009.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 204:2018 has been approved by CEN as EN ISO 204:2018 without any modification.

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SIST EN ISO 204:2018
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SIST EN ISO 204:2018
INTERNATIONAL ISO
STANDARD 204
Third edition
2018-08
Metallic materials — Uniaxial creep
testing in tension — Method of test
Matériaux métalliques — Essai de fluage uniaxial en traction —
Méthode d'essai
Reference number
ISO 204:2018(E)
ISO 2018
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SIST EN ISO 204:2018
ISO 204:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 204:2018
ISO 204:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and designations .......................................................................................................................................................................... 6

5 Principle ........................................................................................................................................................................................................................ 8

6 Apparatus ..................................................................................................................................................................................................................... 8

7 Test pieces ................................................................................................................................................................................................................12

7.1 Shape and dimensions ...................................................................................................................................................................12

7.1.1 Shape and dimension of smooth test pieces .........................................................................................12

7.1.2 Shape and dimension of notched test pieces ........................................................................................13

7.2 Preparation .............................................................................................................................................................................................13

7.3 Determination of the original cross-sectional area ..............................................................................................14

7.4 Marking of the original gauge length, L .........................................................................................................................

o 14

7.5 Determination of the reference length, L .....................................................................................................................

r 14

8 Test procedure .....................................................................................................................................................................................................15

8.1 Heating of the test piece...............................................................................................................................................................15

8.2 Application of the test force ......................................................................................................................................................15

8.3 Test interruptions ..............................................................................................................................................................................16

8.3.1 Planned interruptions of the test ...................................................................................................................16

8.3.2 Multiple test piece machine with several test pieces in line ...................................................16

8.3.3 Combined test..................................................................................................................................................................16

8.3.4 Accidental interruption of the test ................................................................................................................16

8.4 Recording of temperature and elongation or extension ..................................................................................16

8.4.1 Temperature .....................................................................................................................................................................16

8.4.2 Elongation and extension ......................................................................................................................................16

8.4.3 Elongation-time diagram or extension-time diagram ..................................................................17

9 Determination of results ...........................................................................................................................................................................17

10 Test validity .............................................................................................................................................................................................................17

11 Accuracy of the results ................................................................................................................................................................................17

11.1 Expression of the results .............................................................................................................................................................17

11.2 Final uncertainty ................................................................................................................................................................................18

12 Test report ................................................................................................................................................................................................................18

Annex A (informative) Information concerning drift of thermocouples .....................................................................23

Annex B (informative) Information concerning methods of calibration of thermocouples ....................26

Annex C (normative) Creep testing using test pieces with V or blunt circumferential notches ..........27

Annex D (informative) Method of estimating the uncertainty of the measurement in

accordance with the Guide to the expression of uncertainty in measurement (GUM) ............31

Annex E (informative) Representation of results and extrapolation...............................................................................38

Annex F (informative) Computer compatible representation of standards .............................................................48

Bibliography .............................................................................................................................................................................................................................49

© ISO 2018 – All rights reserved iii
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SIST EN ISO 204:2018
ISO 204:2018(E)
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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals,

Subcommittee SC 1, Uniaxial testing.

This third edition cancels and replaces the second edition (ISO 204:2009), which has been technically

revised. The main changes compared to the previous edition are as follows:

— Some of the symbols have been changed to achieve harmonization with the ISO 6892 series.

— For the purpose of this document, the terms “fracture” and “rupture” are interchangeable.

— The term “indicated temperature”, T , has been replaced by “corrected measured temperature”,

T , with errors from all sources being taken into account and any systematic errors having been

corrected. The terms “elongation” and “extension” have been clarified and aligned with the terms

used in the ISO 6892 series. Elongation refers to the test piece deformation measured manually

either during deliberate test interruptions or after fracture, whilst extension is determined by

continuous measurement using an extensometer.

— Some information relating to the calibration of thermocouples has been transferred from an

informative annex into the main body of the document.

— Some changes have been made to Table 1 and formulae have been amended using reference length, L .

— Equation E.1 (now Formula C.1) has been corrected.

— A new informative annex relating to computer compatible representation of standards has been added.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved
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SIST EN ISO 204:2018
ISO 204:2018(E)
Introduction

Creep is the phenomenon exhibited by materials which slowly deform when subjected to loading at

elevated temperature. This document is concerned with the method used to measure such material

behaviour.

Annexes are included concerning temperature measurement using thermocouples and their

calibration, creep testing test pieces with circumferential V and blunt (Bridgman) notches, estimation

of measurement uncertainty, methods of extrapolation of creep rupture life and information about

computer compatible representation of standards.

NOTE 1 Information is still sought relating to the influence of off-axis loading or bending on the creep

properties of various materials. Based on the future availability of quantitative data, consideration might be given

as to whether the maximum amount of bending should be specified and an appropriate calibration procedure be

[43]

recommended. The decision will need to be based on the availability of quantitative data .

NOTE 2 Information concerning the benefit of standards being produced in a computer compatible format is

given in Annex F.

This document incorporates many recommendations developed through the European Creep

Collaborative Committee (ECCC).

NOTE 3 Several different gauge lengths and reference lengths are specified in this document. These lengths

reflect custom and practice used in different laboratories throughout the world. In some cases, the lengths are

physically marked on the test piece as lines or ridges; in other cases, the length can be a virtual length based

upon calculations to determine an appropriate length to be used for the determination of creep elongation. For

some test pieces, L , L and L are the same length (see 3.1, 3.2 and 3.3). “Extension” is used for uninterrupted

r o e

creep test with continuous measurement of the increase of the length of the test piece by using an extensometer.

“Elongation” is mainly used for interrupted creep test with the manual measurement of the increase of the length

of the test piece.
NOTE 4 For many applications, the term “strain” is synonymous with extension.
© ISO 2018 – All rights reserved v
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SIST EN ISO 204:2018
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SIST EN ISO 204:2018
INTERNATIONAL STANDARD ISO 204:2018(E)
Metallic materials — Uniaxial creep testing in tension —
Method of test
1 Scope
This document specifies the methods for
a) uninterrupted creep tests with continuous monitoring of extension,
b) interrupted creep tests with periodic measurement of elongation,
c) stress rupture tests where normally only the time to fracture is measured,

d) a test to verify that a predetermined time can be exceeded under a given force, with the elongation

or extension not necessarily being reported.

NOTE A creep test can be continued until fracture has occurred or it can be stopped before fracture.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature

ISO 6892-2, Metallic materials — Tensile testing — Part 2: Method of test at elevated temperature

ISO 7500-2, Metallic materials — Verification of static uniaxial testing machines — Part 2: Tension creep

testing machines — Verification of the applied force

ISO 9513, Metallic materials — Calibration of extensometer systems used in uniaxial testing

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
reference length

base length used for the calculation of either percentage elongation or percentage extension

Note 1 to entry: A method to calculate this value is given in 7.5.
3.2
original gauge length

length between gauge length marks on the test piece measured at ambient temperature before the test

Note 1 to entry: In general, L ≥ 5D.
© ISO 2018 – All rights reserved 1
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SIST EN ISO 204:2018
ISO 204:2018(E)
3.3
extensometer gauge length
distance between the measuring points of the extensometer
3.4
parallel length
length of the parallel reduced section of the test piece
3.5
final gauge length after fracture

length between gauge length marks on the test piece measured after fracture, at ambient temperature,

with the pieces carefully fitted back together with their axes in a straight line

3.6
original cross-sectional area

cross-sectional area of the parallel length as determined at ambient temperature prior to testing

3.7
minimum cross-sectional area after fracture

minimum cross-sectional area of the parallel length as determined at ambient temperature after

fracture, with the pieces carefully fitted back together with their axes in a straight line

3.8
initial stress
applied force divided by the original cross-section area, S , of the test piece
3.9
extension
increase of extensometer gauge length, L , at time t and at test temperature
Note 1 to entry: For further information, see 6.2.
3.10
elongation
increase of original gauge length, L , at time t
Note 1 to entry: For further information, see 6.2.
3.11
percentage extension

extension at test temperature expressed as a percentage of the reference length, L , as given in Formula (1)

e =×100 (1)
Note 1 to entry: See Figure 1.
2 © ISO 2018 – All rights reserved
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SIST EN ISO 204:2018
ISO 204:2018(E)
3.12
percentage elongation

elongation expressed as a percentage of the reference length, L , as given in Formula (2)

A =×100 (2)
3.13
percentage elastic extension

extension at test temperature expressed as a percentage of the reference length, L , which is proportional

to the initial stress, R

Note 1 to entry: This value can be calculated from the stress/percentage extension values during loading. See 8.4.2.

Note 2 to entry: See Figure 1.
3.14
percentage initial total extension

extension at test temperature expressed as a percentage of the reference length, L , at end of loading

with the initial stress, R
Note 1 to entry: See Figure 1.
3.15
percentage initial plastic extension

extension at end of loading and at test temperature with the initial stress, R , expressed as a percentage

of the reference length, L , and determined as the difference between the percentage initial total

extension, e , and the percentage elastic extension, e , as given in Formula (3)
ti e
e = e − e (3)
i ti e
Note 1 to entry: See Figure 1.

Note 2 to entry: This value represents the plastic extension during the loading phase.

3.16
percentage total extension

extension at the test force at time t and at test temperature, expressed as a percentage of the reference

length, L
Note 1 to entry: See Figure 1.
3.17
percentage plastic extension

extension at time t and at test temperature determined as the difference between the percentage total

extension, e , and the percentage elastic extension, e , expressed as a percentage of the reference length,

t e
L , as given in Formula (4)
e = e − e (4)
p t e
Note 1 to entry: See Figure 1.
© ISO 2018 – All rights reserved 3
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SIST EN ISO 204:2018
ISO 204:2018(E)
3.18
percentage total ultimate extension

total extension at rupture and at test temperature, expressed as a percentage of the reference length, L

3.19
percentage creep extension

extension at loading determined and at test temperature as the difference between the percentage

plastic extension, e , and the percentage initial plastic extension, e , expressed as a percentage of the

p i
reference length, L , as given in Formula (5)
e = e − e (5)
f p i
Note 1 to entry: See Figure 1.
Note 2 to entry: Suffix f originates from “fluage”, “creep” in French.
3.20
percentage anelastic extension

negative extension at end of unloading at test temperature, expressed as a percentage of the reference

length, L
Note 1 to entry: See Figure 1 and 8.4.
3.21
percentage permanent extension
per

extension at end of unloading and at test temperature determined as the difference between the

percentage total extension, e , and the sum of percentage elastic extension, e , plus the percentage

t e

anelastic extension, e , expressed as a percentage of the reference length, L , as given in Formula (6)

k r
e = e – (e + e) (6)
per t e k

Note 1 to entry: In the case of e ≈ 0, the following relationship may be used: e ≈ e .

k per p
Note 2 to entry: See Figure 1.
3.22
percentage permanent elongation
per

elongation expressed as a percentage of the reference length, L , at end of unloading and at room

temperature
3.23
percentage elongation after creep fracture

permanent elongation after fracture, L − L , expressed as a percentage of the reference length, L , as

u o r
given in Formula (7)
LL−
A = ×100 (7)

Note 1 to entry: A may have the specified temperature, T, in degrees Celsius as superscript and the initial stress,

R , in megapascals as subscript; see the example in Table 1.
4 © ISO 2018 – All rights reserved
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SIST EN ISO 204:2018
ISO 204:2018(E)
3.24
percentage reduction of area after creep fracture

maximum change in cross-sectional area measured after fracture, S − S , expressed as a percentage of

o u
the original cross-sectional area, S , as given in Formula (8)
SS−
Z = ×100 (8)

Note 1 to entry: Z may have the specified temperature, T, in degrees Celsius as superscript and the initial stress,

R , in megapascals as subscript; see the example in Table 1.
3.25
creep extension time

time required for a strained test piece to obtain a specified percentage creep extension, x, at the

specified temperature, T, and the initial stress, R
EXAMPLE t
f0,2
3.26
plastic extension time

time required to obtain a specified percentage plastic extension, x, at the specified temperature, T, and

the initial stress, R

Note 1 to entry: An example for t is given in Figure E.2 a) (t = 100 000 h corresponds to e = 1 % at

p1 p1 p
R = 120 MPa).
3.27
creep rupture time

time to rupture for a test piece maintained at the specified temperature, T, and the initial stress, R

Note 1 to entry: The symbol t can have as superscript the specified temperature, T, in degrees Celsius and as

subscript the initial stress, R , in megapascals; see the example in Table 1.
3.28
single test piece machine
testing machine that permits straining of a single test piece
3.29
multiple test piece machine

testing machine that permits straining of more than one test piece simultaneously at the same

temperature
© ISO 2018 – All rights reserved 5
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SIST EN ISO 204:2018
ISO 204:2018(E)
4 Symbols and designations
The symbols and corresponding designations are given in Table 1.
Table 1 — Symbols and designations
Symbol Unit Designation
D mm Diameter of gauge length of a cylindrical test piece
D mm Diameter of gauge length containing a notch
d mm Diameter of gauge length without a notch in a combined notched/unnotched
test piece (see Figure C.1)
d mm Diameter across root of circumferential notch
For a combined notched/unnotched test piece d = d

b mm Width of the cross-section of the parallel length of a test piece of square or rec-

tangular cross-section
L mm Reference length

a mm Thickness of a test piece of square or rectangular cross-section [see Figure 2 b)]

ΔL Increase of extensometer gauge length at time t
ΔL mm Increase of original gauge length at time t
L mm Original gauge length
L mm Parallel gauge length containing a notch
L mm Final gauge length after fracture
L mm Parallel length
L mm Extensometer gauge length
r mm Transition radius
r mm Notch root radius
S mm Original cross-sectional area of the parallel length
S mm Minimum cross-sectional area after fracture
R MPa Initial stress
e % Percentage extension
e % Percentage elastic extension
e % Percentage creep extension:
e =×100
...

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