EN ISO 12737:1999
(Main)Metallic materials - Determination of plane-strain fracture toughness (ISO 12737:1996)
Metallic materials - Determination of plane-strain fracture toughness (ISO 12737:1996)
2009-10-23 SJ: Inter-standard links were missing. Revised version was published (WI EC001071), but this version was not withdrawn. Decision not to undertake corrective action (GM/MHT).
Migrated from Progress Sheet (TC Comment) (2000-07-10): The results of the PQ has been submitted to ISO/TC 164/SC 4; but in the same time, ESIS had submitted a new version of their recommandation which resulted in CD 12737 "Determination of plane strain structure toughness" which incorporates the elements of EGF-P1:1990. It is actually prepared for the DIS vote. ++ The french translation is being prepared by AFNOR.
Metallische Werkstoffe - Bestimmung der Bruchzähigkeit (ebener Dehnungszustand) (ISO 12737:1996)
Diese internationale Norm legt Richtlinien zur Bestimmung der Bruchzähigkeit homogener metallischer Werkstoffe im Fall des ebenen Dehnungßustandes unter quasi-statischer Belastung fest. Dazu werden gekerbte und mit einem Ermüdungsanriß versehene Proben einer langsam anwachsenden Rißöffnungskraft ausgesetzt.
Matériaux métalliques - Détermination du facteur d'intensité de contrainte critique (ISO 12737:1996)
Metallic materials - Determination of plane-strain fracture toughness (ISO 12737:1996)
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Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 12737:2000
01-december-2000
Metallic materials - Determination of plane-strain fracture toughness (ISO
12737:1996)
Metallic materials - Determination of plane-strain fracture toughness (ISO 12737:1996)
Metallische Werkstoffe - Bestimmung der Bruchzähigkeit (ebener Dehnungszustand)
(ISO 12737:1996)
Matériaux métalliques - Détermination du facteur d'intensité de contrainte critique (ISO
12737:1996)
Ta slovenski standard je istoveten z: EN ISO 12737:1999
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
SIST EN ISO 12737:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 12737:2000
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SIST EN ISO 12737:2000
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SIST EN ISO 12737:2000
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SIST EN ISO 12737:2000
INTERNATIONAL
IS0
STANDARD
12737
First edition
1996-I I-1 5
Metallic materials - Determination
of plane-strain fracture toughness
Mat&-iaux m&alliques - Determination du facteur d’intensitti
de con train te critique
Reference number
IS0 12737:1996(E)
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SIST EN ISO 12737:2000
IS0 12737:1996(E)
Page
Contents
1
1 Scope .
1
.................................................................
2 Normative references
1
..................................................................................
3 Definitions
2
..........................................................
4 Symbols and designations
2
5 Principle .
4
...................................................................................
6 Apparatus
.................... 5
7 Test specimen size, configuration and preparation
7
...................................................................................
8 Procedure
8
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9 Test procedure
..................................... 8
10 Calculation and interpretation of results
8
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11 Test report
Annexes
......... 10
Fatigue precracking of K,, fracture toughness specimens
11
...................................................................
Bend test specimen
13
.....................................................................
Compact specimen
15
Test fixtures .
17
Bibliography .
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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SIST EN ISO 12737:2000
@ IS0 IS0 12737:1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 12737 was prepared by Technical Committee
ISO/TC 164, Mechanical testing of metals, Subcommittee SC 4, Toughness
tes thg.
Annexes A to C form an integral part of this International Standard.
Annexes D and E are for information only.
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SIST EN ISO 12737:2000
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SIST EN ISO 12737:2000
INTERNATIONAL STANDARD @ IS0 IS0 12737:1996(E)
Metallic materials - Determination of plane-strain fracture
toughness
1 Scope
This International Standard specifies the method for determining the plane-strain fracture toughness of
homogeneous metallic materials using a specimen that is notched and precracked by fatigue, and subjected to
slowly increasing crack displacement force.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 7500-I : 1986, Metallic materials - Verification of static uniaxial testing machines - Part I: Tensile testing
machines.
IS0 9513:1989, Metallic materials - Verification of extensome ters used in uniaxial testing.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 plane-strain stress intensity factor, Kl: Magnitude of the elastic stress field at the tip of a crack subjected
to opening mode displacement (mode I). It is a function of applied force and test specimen size, geometry, and
crack length, and has the dimensions of force times length-V
3.2 plane-strain fracture toughness, K,,: Measure, by the operational procedure of this method, of a material’s
resistance to crack extension when the state of stress near the crack tip is predominantly plane strain and plastic
deformation is limited.
NOTE - It is the critical value of Iy, at which significant crack extension occurs on increasing load with high constraint to
plastic deformation.
1
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SIST EN ISO 12737:2000
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IS0 12737:1996(E)
3.3 crack plane orientation: Method for relating the plane and direction of crack extension to the characteristic
directions of the product.
NOTE - A hyphenated code is used wherein the letter(s) preceding the hyphen represent(s) the direction normal to the crack
plane and the letter(s) following the hyphen represent(s) the anticipated direction of crack extension (see figure 1). For wrought
metals, the letter X always denotes the principal direction of grain flow, Z the direction of principal working force, and Y the
direction normal to the X-Z plane. If specimen directions do not coincide with the product’s characteristic directions, then two
letters are used to denote the normal to the crack plane and/or the expected direction of crack extension [see figure 1 b)]. If
there is no grain flow direction (as in a casting), reference axes may be arbitrarily assigned but must be clearly identified.
3.4 notch opening displacement, V: Displacement measured at or near the notch mouth.
4 Symbols and designations
For the purposes of this International Standard the following symbols apply (see also figures 1, 2 and 4).
Designation
Symbol Unit
a mm Crack length
mm Specimen thickness
B
E MPa Young’s modulus
F kN Applied force
Particular value of F (see figure 4)
kN
Fcr
kN Particular value of F (see figure 4)
F5
Mpa.m I/*‘)
Maximum stress intensity factor during the final stage of fatigue cracking
Kf
MPa.m 112 Provisional value of K,,
KQ
Opening mode stress intensity factor (mode I)
MPa.m 112
Kl
MPa.m 112 Critical value of K, (plane-strain fracture toughness)
4,
R Ratio of minimum to maximum fatigue cracking force during any single cycle
of fatigue operation
MPa 0,2 % offset yield strength
RP0,2
S mm Span between outer loading points
V mm Notch opening displacement
Width for bend specimen or effective width for compact specimen
W mm
MPa.m 112 Difference between maximum and minimum values of K, during any single
*4
cycle of fatigue operation
I) 0,031 6 MPa.ml/* = 1 N+mm--3/* = 0,031 6 MN-m-312
5 Principle
This method covers the determination of the plane strain fracture toughness (K,,) of metallic materials by
increasing-force tests of fatigue-precracked test specimens. Details of the test specimens and experimental
procedures are given in annexes B and C. Force versus notch opening displacement is recorded autographically,
or converted to digital form for accumulation in a computer information storage facility and subsequent processing.
The force corresponding to 2 % apparent crack extension is established by a specified deviation from the
linear portion of the test record. If certain validity requirements are satisfied, the value of Klc is calculated from this
force.
2
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SIST EN ISO 12737:2000
ISO 12737:1996(E)
Grain flow
flow
CX
a) Basic identification
b) Non-basic identlflcation
xz
iv
Y
X
X
Z Y
Z-Y Z
6
9
Y
J z-x
‘0
z Y
x Y
k
k
X-Y
X
Z
x-z
fl
c) Radial grain flow, axial working direction
d) Axial grain flow, radial working direction
Figure 1 - Crack plane identification
The property K,, characterizes the resistance of a material to fracture in the presence of a sharp crack under severe
tensile constraint, such that
a) the state of stress near the crack front approaches plane strain; and
b) the crack-tip plastic zone is small compared to the crack size, specimen thickness, and ligament ahead of the
crack.
K,, is believed to represent a lower limiting value of fracture toughness in the environment and at the temperature
of test.
Cyclic or sustained loads can cause crack extension at KI values less than K,,. Crack extension under cyclic or
sustained loads can be influenced by temperature and environment. Therefore when Kr, is applied to the design of
service components, differences between laboratory test and field conditions should be considered.
3
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SIST EN ISO 12737:2000
@ IS0
IS0 1’2737: 1996(E)
With plane-strain fracture toughness testing, there can be no advance assurance that a valid Kr, will be determined
in a particular test.
6 Apparatus
6.1 Testing machine and load measurement
The testing machine shall be calibrated in accordance with IS0 7500-I and shall be of at least grade 1. The testing
machine shall have provisions for autographic recording of the force applied to the specimen; alternatively, a
computer data acquisition system may be used to record load and displacement for subsequent analysis. The
combination of load-sensing device and recording system shall permit the force FQ (as defined in clause IO) to be
determined from the test record to & 1 %.
6.2 Fatigue cracking machine
When possible, the fatigue machine and load-indicating device shall be calibrated statically in accordance with
IS0 7500-I and shall have a grade of at least 2. If the machine cannot be calibrated statically, the applied force shall
be known to + 2,5 %. Careful alignment of the specimen and fixturing is necessary to encourage straight fatigue
cracks. The fixturing shall be such that the stress distribution is uniform across the specimen thickness and
symmetrical about the plane of the prospective crack.
6.3 Displacement gauge
The displacement gauge electrical output shall represent the relative displacement (V) of two precisely located
gauge positions spanning the notch mouth. The design of the displacement gauge and knife edges shall allow free
rotation of the points of contact between the gauge and the specimen.
The displacement gauge shall be calibrated in accordance with IS0 9513, as interpreted in relation to this method,
and shall be of at least class 1; however, calibration shall be performed at least weekly during the time the gauge is
in use. Periodic verification of greater frequency may be required depending on use and agreement between
contractual parties.
Verification of the gauge shall be performed at the temperature of test to + 5 OC. Response of the gauge shall
correspond to the calibration apparatus to +, 0,003 mm for displacements up to 0,3 mm and + 1 %- for higher
values.
ion of an absolute displacement value is not necessary since only changes in displacement are used
The determinai ti
in this method. Two proven designs of displacement gauge are given in [I] and [Z] (see annex E) and similar gauges
are commercia ly available.
6.4 Testing fixtures
The bend test shall be performed using a fixture designed to minimize friction effects by allowing the support
rollers to rotate and translate slightly as the specimen is loaded, thus achieving rolling contact. A design suitable for
testing bend specimens is shown in figure D.l .
A loading clevis suitable for testing compact specimens is shown in figure D.2.
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SIST EN ISO 12737:2000
@ IS0 IS0 12737:1996(E)
7 Test specimen size, configuration and preparation
7.1 Specimen size
In order for a result to be considered valid according to this method, the specimen thickness (B), crack length (a),
is the 0,2 % offset yield strength of
and ligament length (w-a) must all be not less than 2,5(KI,/XP0 #I where RPO 2
the material in the environment and at the temperature of test. Meeting this requirement cannot be ensured in
advance, thus specimen dimensions should be conservatively established for the first test in a series. If the form of
the available material is such that it is not possible to obtain a test specimen with thickness, crack length and
*, then it is not possible to make a valid K,, measurement
ligament length equal to or greater than 2,5(K,,lRP0 *)
I
according to this method.
7.2 Recommended specimen proportions
72.1 Recommended specimens
The recommended specimens are shown in figures B.l and C.I. Width (W) is nominally twice the thickness (B).
Crack length (a) is between 0,45 and 0,55 times the width.
7.2.2 Alternative proportions
In certain cases it may be necessary or desirable to use specimens having W/B ratios other than 2, and alternative
proportions are allowed (see annex B or C). Specimens having alternative proportions shall nevertheless have the
same crack length-to-width (a/W) ratio as the recommended specimens.
7.2.3 Alternative specimen configurations (for information only)
By prior agreement, alternative specimen configurations and their associated methods of analysis may be used
provided that they be accepted as national standards for K,, testing by an IS0 member body, including those
standards which have the multiple purpose of measuring K,, along with J and/or CTOD (crack tip opening
displacement) properties.
7.2.4 Fatigue crack starter notch
TWO fatigue crack starter notch configurations are shown in figures 2 a) and 2 b). The suggested root radius for the
straight-through slot terminating in a V-notch is 0,lO mm or less. For the chevron form of notch, the suggested root
radius is 0,25 mm or less. The method of notch preparation is discretionary. The starter notch (plus fatigue crack)
must lie within the envelope shown in figure 2 c) (see
...
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