Standard Test Method for Measurement of Fracture Toughness

SIGNIFICANCE AND USE
5.1 Assuming the presence of a preexisting, sharp, fatigue crack, the material fracture toughness values identified by this test method characterize its resistance to: (1)  fracture of a stationary crack, (2) fracture after some stable tearing, (3) stable tearing onset, and (4) sustained stable tearing. This test method is particularly useful when the material response cannot be anticipated before the test. Application of procedures in Test Method E1921 is recommended for testing ferritic steels that undergo cleavage fracture in the ductile-to-brittle transition.  
5.1.1 These fracture toughness values may serve as a basis for material comparison, selection, and quality assurance. Fracture toughness can be used to rank materials within a similar yield strength range.  
5.1.2 These fracture toughness values may serve as a basis for structural flaw tolerance assessment. Awareness of differences that may exist between laboratory test and field conditions is required to make proper flaw tolerance assessment.  
5.2 The following cautionary statements are based on some observations.  
5.2.1 Particular care must be exercised in applying to structural flaw tolerance assessment the fracture toughness value associated with fracture after some stable tearing has occurred. This response is characteristic of ferritic steel in the transition regime. This response is especially sensitive to material inhomogeneity and to constraint variations that may be induced by planar geometry, thickness differences, mode of loading, and structural details.  
5.2.2 The J-R curve from bend-type specimens recommended by this test method (SE(B), C(T), and DC(T)) has been observed to be conservative with respect to results from tensile loading configurations.  
5.2.3 The values of δc, δu, Jc, and J u   may be affected by specimen dimensions.
SCOPE
1.1 This test method covers procedures and guidelines for the determination of fracture toughness of metallic materials using the following parameters: K, J, and CTOD (δ). Toughness can be measured in the R-curve format or as a point value. The fracture toughness determined in accordance with this test method is for the opening mode (Mode I) of loading.  
1.2 The recommended specimens are single-edge bend, [SE(B)], compact, [C(T)], and disk-shaped compact, [DC(T)]. All specimens contain notches that are sharpened with fatigue cracks.  
1.2.1 Specimen dimensional (size) requirements vary according to the fracture toughness analysis applied. The guidelines are established through consideration of material toughness, material flow strength, and the individual qualification requirements of the toughness value per values sought.  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
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 and health practices and determine the applicability of regulatory limitations prior to use. Note 1—Other standard methods for the determination of fracture toughness using the parameters K, J, and CTOD are contained in Test Methods E399, E1290, and E1921. This test method was developed to provide a common method for determining all applicable toughness parameters from a single test.

General Information

Status
Historical
Publication Date
30-Apr-2011
Technical Committee
Drafting Committee
Current Stage
Ref Project

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ASTM E1820-11e1 - Standard Test Method for Measurement of Fracture Toughness
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: E1820 − 11
StandardTest Method for
1
Measurement of Fracture Toughness
This standard is issued under the fixed designation E1820; 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
ε NOTE—3.2.2 and Note A13.3 were editorially revised in March 2013.
1. Scope E8/E8MTest Methods for Tension Testing of Metallic Ma-
terials
1.1 This test method covers procedures and guidelines for
E21TestMethodsforElevatedTemperatureTensionTestsof
the determination of fracture toughness of metallic materials
Metallic Materials
using the following parameters: K, J, and CTOD (δ). Tough-
E23Test Methods for Notched Bar Impact Testing of Me-
nesscanbemeasuredintheR-curveformatorasapointvalue.
tallic Materials
The fracture toughness determined in accordance with this test
E399Test Method for Linear-Elastic Plane-Strain Fracture
method is for the opening mode (Mode I) of loading.
Toughness K of Metallic Materials
Ic
1.2 The recommended specimens are single-edge bend,
E1290Test Method for Crack-Tip Opening Displacement
[SE(B)], compact, [C(T)], and disk-shaped compact, [DC(T)].
(CTOD) Fracture Toughness Measurement (Withdrawn
All specimens contain notches that are sharpened with fatigue
3
2013)
cracks.
E1823TerminologyRelatingtoFatigueandFractureTesting
1.2.1 Specimen dimensional (size) requirements vary ac-
E1921 Test Method for Determination of Reference
cording to the fracture toughness analysis applied. The guide-
Temperature, T , for Ferritic Steels in the Transition
o
lines are established through consideration of material
Range
toughness, material flow strength, and the individual qualifi-
E1942Guide for Evaluating DataAcquisition Systems Used
cation requirements of the toughness value per values sought.
in Cyclic Fatigue and Fracture Mechanics Testing
1.3 The values stated in SI units are to be regarded as the
E2298Test Method for Instrumented Impact Testing of
standard. The values given in parentheses are for information
Metallic Materials
only.
3. Terminology
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.1 Terminology E1823 is applicable to this test method.
responsibility of the user of this standard to establish appro-
Only items that are exclusive to Test Method E1820, or that
priate safety and health practices and determine the applica-
have specific discussion items associated, are listed in this
bility of regulatory limitations prior to use.
section.
NOTE 1—Other standard methods for the determination of fracture
3.2 Definitions of Terms Specific to This Standard:
toughness using the parameters K, J, and CTOD are contained in Test −1
3.2.1 compliance [LF ], n—the ratio of displacement in-
Methods E399, E1290, and E1921. This test method was developed to
crement to force increment.
provide a common method for determining all applicable toughness
parameters from a single test.
3.2.2 crack opening displacement (COD) [L], n—force-
inducedseparationvectorbetweentwopointsataspecificgage
2. Referenced Documents
length.Thedirectionofthevectorisnormaltothecrackplane.
2
2.1 ASTM Standards:
3.2.2.1 Discussion—In this practice, displacement, v, is the
E4Practices for Force Verification of Testing Machines
total displacement measured by clip gages or other devices
spanning the crack faces.
1
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
3.2.3 crack extension, ∆a [L], n—an increase in crack size.
and Fracture and is the direct responsibility of Subcommittee E08.07 on Fracture
Mechanics.
−1 −2
3.2.4 crack-extension force, G [FL or FLL ], n—the
Current edition approved May 1, 2011. Published August 2011. Originally
ε1
elastic energy per unit of new separation area that is made
approved in 1996. Last previous edition approved in 2009 as E1820–09 . DOI:
10.1520/E1820-11E01.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E1820 − 11
*
availableatthefrontofanidealcrackinanelasticsolidduring 3.2.6.5 Discussion—In CTOD testing, δ [L] characterizes
c
a virtual increment of forward crack extension. theCTODfracturetoughnessofmaterialsatfractureinstability
prior to the onset o
...

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