ISO/DIS 12135

Metallic materials -- Unified method of test for the determination of quasistatic fracture toughness

Matériaux métalliques -- Méthode unifiée d'essai pour la détermination de la ténacité quasi statique

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 12135
ISO/TC 164/SC 4 Secretariat: ANSI
Voting begins on: Voting terminates on:
2020-01-31 2020-04-24
Metallic materials — Unified method of test for the
determination of quasistatic fracture toughness

Matériaux métalliques — Méthode unifiée d'essai pour la détermination de la ténacité quasi statique

ICS: 77.040.10
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,
This document is circulated as received from the committee secretariat.
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
Reference number
NATIONAL REGULATIONS.
ISO/DIS 12135:2020(E)
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. ISO 2020
---------------------- Page: 1 ----------------------
ISO/DIS 12135:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 12135:2020(E)
Contents

Foreword ........................................................................................................................................................................ vi

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

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

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

4 Symbols and designations ........................................................................................................................... 2

Table 1 — Symbols and their designations ......................................................................................................... 2

5 General requirements .................................................................................................................................. 5

5.1 General ............................................................................................................................................................... 5

5.2 Fracture parameters ..................................................................................................................................... 6

5.3 Fracture toughness symbols ...................................................................................................................... 7

Table 2 — Fracture toughness symbols ............................................................................................................... 7

5.4 Test specimens ................................................................................................................................................ 7

5.4.1 Specimen configuration and size .............................................................................................................. 7

5.4.2 Specimen preparation ................................................................................................................................11

5.5 Pre-test requirements ................................................................................................................................17

5.5.1 Pre-test measurements ..............................................................................................................................17

5.5.2 Crack shape/length requirements .........................................................................................................17

5.6 Test apparatus...............................................................................................................................................18

5.6.1 Calibration ......................................................................................................................................................18

5.6.2 Force application ..........................................................................................................................................18

5.6.3 Displacement measurement ....................................................................................................................18

5.6.4 Test fixtures ...................................................................................................................................................18

5.7 Test requirements .......................................................................................................................................22

5.7.1 Three-point bend testing...........................................................................................................................22

5.7.2 Compact tension testing ............................................................................................................................22

5.7.3 Specimen test temperature ......................................................................................................................22

5.7.4 Recording ........................................................................................................................................................22

5.7.5 Testing rates ..................................................................................................................................................23

5.7.6 Test analyses ..................................................................................................................................................23

5.8 Post-test crack measurements ................................................................................................................23

5.8.1 General .............................................................................................................................................................23

5.8.2 Initial crack length, a .................................................................................................................................23

5.8.3 Stable crack extension, Δa ........................................................................................................................26

5.8.4 Unstable crack extension ..........................................................................................................................26

6 Determination of fracture toughness for stable and unstable crack extension ....................27

6.1 General .............................................................................................................................................................27

6.2 Determination of plane strain fracture toughness, K ...................................................................27

6.2.1 General .............................................................................................................................................................27

6.2.2 Interpretation of the test record for F ................................................................................................27

6.2.3 Calculation of K ...........................................................................................................................................28

6.2.4 Qualification of K as K .............................................................................................................................29

Q lc

6.3 Determination of fracture toughness in terms of δ .........................................................................29

6.3.1 Determination of F and V , F and V , or F and V .........................................................................29

c c u u uc uc

6.3.2 Determination of F and V ......................................................................................................................30

m m

6.3.3 Determination of V .....................................................................................................................................31

6.3.4 Calculation of δ ............................................................................................................................................31

6.3.5 Qualification of δ fracture toughness value .....................................................................................32

6.4 Determination of fracture toughness in terms of J ..........................................................................33

6.4.1 Determination of F and V or q , F and V or q , or F and V or q .........................................33

c c c u u u uc uc uc
ii © ISO 2020 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/DIS 12135:2020(E)

6.4.2 Determination of F and q ..................................................................................................................... 33

m m

6.4.3 Determination of U .................................................................................................................................... 33

6.4.4 Calculation of J ............................................................................................................................................. 34

6.4.5 Qualification of J fracture toughness value ....................................................................................... 35

7 Determination of resistance curves δ-Δa and J-Δa and initiation toughness δ and J

0,2BL 0,2BL

and δ and J for stable crack extension ................................................................................................ 35

i i

7.1 General ............................................................................................................................................................ 35

7.2 Test procedure ............................................................................................................................................. 36

7.2.1 General ............................................................................................................................................................ 36

7.2.2 Multiple-specimen procedure ................................................................................................................. 36

7.2.3 Single-specimen procedure ..................................................................................................................... 36

7.2.4 Final crack front straightness ................................................................................................................. 36

7.3 Calculation of J and δ .................................................................................................................................. 36

7.3.1 Calculation of J .............................................................................................................................................. 36

7.3.2 Calculation of δ ............................................................................................................................................. 37

7.4 R-curve plot .................................................................................................................................................... 37

7.4.1 Plot construction.......................................................................................................................................... 37

7.4.2 Data spacing and curve fitting ................................................................................................................ 39

7.5 Qualification of resistance curves ......................................................................................................... 39

7.5.1 Qualification of J-Δa resistance curves ................................................................................................ 39

7.5.2 Qualification of δ−Δa resistance curves .............................................................................................. 40

7.6 Determination and qualification of J and δ .......................................................................... 41

0,2BL 0,2BL

7.6.1 Determination of J ................................................................................................................................ 41

0,2BL

7.6.2 Determination of δ ............................................................................................................................... 41

0,2BL

7.7 Determination of initiation toughness J and δ by scanning electron microscopy (SEM) . 42

i i

8 Test report ..................................................................................................................................................... 42

8.1 Organization .................................................................................................................................................. 42

8.2 Specimen, material and test environment ......................................................................................... 42

8.2.1 Specimen description ................................................................................................................................. 43

8.2.2 Specimen dimensions ................................................................................................................................ 43

8.2.3 Material description ................................................................................................................................... 43

8.2.4 Additional dimensions ............................................................................................................................... 43

8.2.5 Test environment ........................................................................................................................................ 43

8.2.6 Fatigue precracking conditions .............................................................................................................. 43

8.3 Test data qualification ............................................................................................................................... 44

8.3.1 Limitations ..................................................................................................................................................... 44

8.3.2 Crack length measurements .................................................................................................................... 44

8.3.3 Fracture surface appearance................................................................................................................... 44

8.3.4 Pop-in ............................................................................................................................................................... 44

8.3.5 Resistance curves ........................................................................................................................................ 44

8.3.6 Checklist for data qualification............................................................................................................... 44

8.4 Qualification of K ....................................................................................................................................... 45

8.5 Qualification of the δ-R Curve ................................................................................................................. 46

8.6 Qualification of the J-R Curve .................................................................................................................. 46

8.7 Qualification of δ as δ ............................................................................................................... 46

0,2BL(B) 0,2BL

8.8 Qualification of J as J ................................................................................................................. 46

0,2BL(B) 0,2BL

Annex A (informative) Determination of δ and J ......................................................................................... 47

i i

A.1 Critical stretch zone width (SZW) measurement ............................................................................. 47

A.2 Determination of δ ..................................................................................................................................... 49

A.3 Determination of J ...................................................................................................................................... 51

© ISO 2020 – All rights reserved iii
---------------------- Page: 4 ----------------------
ISO/DIS 12135:2020(E)

Annex B (normative) Crack plane orientation................................................................................................52

Annex C (informative) Example test reports ...................................................................................................53

C.1 Specimen, material and test environment ..........................................................................................53

C.2 Data qualification .........................................................................................................................................54

C.3 Resistance curve data .................................................................................................................................57

C.4 Qualification of K as K .............................................................................................................................57

Q lc

C.5 Qualification of δ-R curve ..........................................................................................................................58

C.6 Qualification of J-R curve ...........................................................................................................................59

C.7 Qualification of δ as δ .............................................................................................................59

Q0,2BL(B) 0,2BL

Qualification of J as J ...................................................................................................................60

Q0,2BL 0,2BL
C.8

Annex D (normative) Stress intensity factor coefficients and compliance relationships ...............62

D.1 Stress intensity factor coefficients .........................................................................................................62

D.1.1 Three-point bend specimens ...................................................................................................................62

D.1.2 Compact specimens .....................................................................................................................................62

D.2 Elastic compliance relationship ..............................................................................................................65

D.2.1 Three-point bend specimens instrumented for measurement of force F versus crack-

mouth opening displacement V ...........................................................................................................65

D.2.2 Straight-notch compact specimens instrumented for measurement of F versus crack-

mouth opening displacement V ...........................................................................................................65

D.2.3 Three-point bend specimens instrumented for measurement of F versus load-line

displacement q ...........................................................................................................................................65

D.2.4 Stepped-notch compact specimens instrumented for measurement of F versus load-line

displacement q ...........................................................................................................................................66

Annex E (informative) Measurement of load-line displacement q in the three-point bend test ..67

Figure E.3 — Displacements associated with three-point bend specimens ..........................................69

Figure E.5 — Location of two notch-opening displacements measurements (V and V ) for the

g1 g2

determination of load-line displacement ............................................................................................70

Annex F (informative) Derivation of pop-in formulae .................................................................................72

Figure F.1 — Forces and elastic displacements associated with multiple pop-ins .............................72

Annex G (informative) Analytical methods for the determination of V and U .................................73

p p

G.1 General .............................................................................................................................................................73

G.2 Plastic displacement, V .............................................................................................................................73

G.3 Plastic area, U ...............................................................................................................................................74

Annex H (informative) Guidelines for single-specimen methods............................................................75

H.1 General .............................................................................................................................................................75

H.2 Unloading compliance technique ...........................................................................................................75

H.3 Test recommendations ..............................................................................................................................76

H.3.1 Compliance measurement ........................................................................................................................76

H.3.2 Digital signal resolution.............................................................................................................................76

iv © ISO 2020 – All rights reserved
---------------------- Page: 5 ----------------------
ISO/DIS 12135:2020(E)

H.3.3 Autographic signal resolution ................................................................................................................. 76

H.4 Procedure ....................................................................................................................................................... 76

H.4.1 Precycling ....................................................................................................................................................... 76

H.4.2 Loading rate ................................................................................................................................................... 76

H.4.3 Crack length measurements .................................................................................................................... 77

H.4.4 Termination of test ..................................................................................................................................... 77

H.5 Crack length calculation ............................................................................................................................ 77

H.5.1 Bend specimen: Crack-mouth opening displacement (CMOD) measured at the specimen

surface ............................................................................................................................................................. 77

H.5.2 Bend specimen: Compliance based on load-point displacement ............................................... 78

H.5.3 Compact specimens .................................................................................................................................... 78

H.5.4 Rotation correction for compact specimens ...................................................................................... 80

H.6 Resistance to crack extension ................................................................................................................. 80

H.6.1 General ............................................................................................................................................................ 80

H.6.2 Estimated initial crack length ................................................................................................................. 81

H.6.3 Estimated crack extension ....................................................................................................................... 82

H.6.4 Resistance curves ........................................................................................................................................ 82

H.7 Electrical potential techniques ............................................................................................................... 82

H.7.1 AC potential method ................................................................................................................................... 82

H.7.2 Interpretation of test records ................................................................................................................. 83

H.8 DC potential methods ................................................................................................................................. 84

H.8.1 Method 1 ......................................................................................................................................................... 84

H.8.1.1 Procedure ....................................................................................................................................................... 84

H.8.1.2 Interpretation of test records ................................................................................................................. 86

H.8.2 Method 2 ......................................................................................................................................................... 86

H.8.2.1 Procedure ....................................................................................................................................................... 86

H.8.2.2 Interpretation of test records ................................................................................................................. 87

Annex I (normative) Power-law fits to crack extension data (see Reference [45]) .......................... 89

Bibliography ................................................................................................................................................................ 90

© ISO 2020 – All rights reserved v
---------------------- Page: 6 ----------------------
ISO/DIS 12135:2020(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 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.
The committee responsible for this document is ISO/TC 164, Mecha
...