ASTM E1304-97(2020)

Standard Test Method for Plane-Strain (Chevron-Notch) Fracture Toughness of Metallic Materials

SIGNIFICANCE AND USE
5.1 The fracture toughness determined by this test method characterizes the resistance of a material to fracture by a slowly advancing steady-state crack (see 3.2.5) in a neutral environment under severe tensile constraint. The state of stress near the crack front approaches plane strain, and the crack-tip plastic region is small compared with the crack size and specimen dimensions in the constraint direction. A KIv  or KIvj  value may be used to estimate the relation between failure stress and defect size when the conditions described above would be expected, although the relationship may differ from that obtained from a KIc  value (see Note 1). Background information concerning the basis for development of this test method in terms of linear elastic fracture mechanics may be found in Refs (6-15).  
5.1.1 The KIv, KIvj, or KIvM  value of a given material can be a function of testing speed (strain rate) and temperature. Furthermore, cyclic forces can cause crack extension at KI  values less than KIv, and crack extension can be increased by the presence of an aggressive environment. Therefore, application of KIv  in the design of service components should be made with an awareness of differences that may exist between the laboratory tests and field conditions.  
5.1.2 Plane-strain fracture toughness testing is unusual in that there can be no advance assurance that a valid KIv, KIvj, or KIvM  will be determined in a particular test. Therefore, it is essential that all the criteria concerning the validity of results be carefully considered as described herein.  
5.2 This test method can serve the following purposes:  
5.2.1 To establish the effects of metallurgical variables such as composition or heat treatment, or of fabricating operations such as welding or forming, on the fracture toughness of new or existing materials.  
5.2.2 For specifications of acceptance and manufacturing quality control, but only when there is a sound basis for specification of minimum ...
SCOPE
1.1 This test method covers the determination of plane-strain (chevron-notch) fracture toughnesses, KIv  or KIvM, of metallic materials. Fracture toughness by this method is relative to a slowly advancing steady state crack initiated at a chevron-shaped notch, and propagating in a chevron-shaped ligament (Fig. 1). Some metallic materials, when tested by this method, exhibit a sporadic crack growth in which the crack front remains nearly stationary until a critical load is reached. The crack then becomes unstable and suddenly advances at high speed to the next arrest point. For these materials, this test method covers the determination of the plane-strain fracture toughness, KIvj  or KIvM, relative to the crack at the points of instability.        
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 14-May-2020
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: E08 - Fatigue and Fracture
• Drafting Committee: E08.07 - Fracture Mechanics

Relations

• Refers: ASTM E1823-20 - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 01-Feb-2020

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1304 − 97 (Reapproved 2020)
Standard Test Method for
Plane-Strain (Chevron-Notch) Fracture Toughness of
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Metallic Materials
This standard is issued under the fixed designation E1304; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This test method covers the determination of plane-
1.5 This international standard was developed in accor-
strain (chevron-notch) fracture toughnesses, K or K ,of
Iv IvM
dance with internationally recognized principles on standard-
metallic materials. Fracture toughness by this method is
ization established in the Decision on Principles for the
relative to a slowly advancing steady state crack initiated at a
Development of International Standards, Guides and Recom-
chevron-shaped notch, and propagating in a chevron-shaped
mendations issued by the World Trade Organization Technical
ligament (Fig. 1). Some metallic materials, when tested by this
Barriers to Trade (TBT) Committee.
method, exhibit a sporadic crack growth in which the crack
front remains nearly stationary until a critical load is reached.
2. Referenced Documents
The crack then becomes unstable and suddenly advances at
2
2.1 ASTM Standards:
highspeedtothenextarrestpoint.Forthesematerials,thistest
E4Practices for Force Calibration and Verification of Test-
method covers the determination of the plane-strain fracture
toughness, K or K , relative to the crack at the points of ing Machines
Ivj IvM
E8/E8MTest Methods for Tension Testing of Metallic Ma-
instability.
terials
NOTE 1—One difference between this test method and Test Method
E399Test Method for Linear-Elastic Plane-Strain Fracture
E399 (which measures K ) is that Test Method E399 centers attention on
Ic
Toughness of Metallic Materials
the start of crack extension from a fatigue precrack. This test method
E1823TerminologyRelatingtoFatigueandFractureTesting
makes use of either a steady state slowly propagating crack, or a crack at
the initiation of a crack jump. Although both methods are based on the
principles of linear elastic fracture mechanics, this difference, plus other
3. Terminology
differences in test procedure, may cause the values from this test method
tobelargerthan K valuesinsomematerials.Therefore,toughnessvalues 3.1 Definitions:
Ic
determined by this test method cannot be used interchangeably with K .
Ic 3.1.1 The terms described in Terminology E1823 are appli-
cable to this test method.
1.2 This test method uses either chevron-notched rod speci-
−3/2
3.1.2 stress-intensity factor, K [FL ]—the magnitude of
mens of circular cross section, or chevron-notched bar speci- I
the mathematically ideal crack-tip stress field (stress-field
mens of square or rectangular cross section (Figs. 1-10). The
singularity) for mode I in a homogeneous linear-elastic body.
terms “short rod” and “short bar” are used commonly for these
3.1.2.1 Discussion—Valuesof Kformode Iaregivenbythe
types of chevron-notched specimens.
following equation:
1.3 The values stated in inch-pound units are to be regarded
½
K 5 limit σ 2πr
@ #
I y x
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only r →0
x
and are not considered standard.
where:
1.4 This standard does not purport to address all of the
r = distance from the crack tip to a location where the
x
safety concerns, if any, associated with its use. It is the
stress is calculated and
responsibility of the user of this standard to establish appro-
σ = the principal stress r normal to the crack plane.
y x
3.2 Definitions of Terms Specific to This Standard:
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This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.07 on Fracture
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Mechanics. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 15, 2020. Published May 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1989. Last previous edition approved in 2014 as E1304–97(2014). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/E1304-97R20. the ASTM website.
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