ASTM B645-21

Standard Practice for Linear-Elastic Plane-Strain Fracture Toughness Testing of Aluminum Alloys

SIGNIFICANCE AND USE
5.1 This practice for plane-strain fracture toughness testing of aluminum alloys may be used as a supplement to Test Method E399. The application of this practice is primarily intended for quality assurance and material release in cases where valid plane-strain fracture toughness data cannot be obtained per Test Method E399.  
5.2 It must be understood that the interpretations and guidelines in this practice do not alter the validity requirements of Test Method E399 or promote the designation of data that are invalid according to Test Method E399 to a “valid” condition. This practice is primarily concerned with cases where it is not possible or practical to obtain valid data, but where material release judgments must be made against specified fracture toughness values. Where it is possible to obtain a valid plane-strain fracture toughness value by replacement testing according to Test Method E399, that is the preferred approach.
SCOPE
1.1 This practice is applicable to the fracture toughness testing of all aluminum alloys, tempers, and products, especially in cases where the tests are being made to establish whether or not individual lots meet the requirements of specifications and should be released to customers.  
1.2 Test Method E399 is the basic test method to be used for plane-strain fracture toughness testing of aluminum alloys. The purpose of this practice is to provide supplementary information for plane-strain fracture toughness of aluminum alloys in three main areas:  
1.2.1 Specimen sampling,  
1.2.2 Specimen size selection, and  
1.2.3 Interpretation of invalid test results.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3.1 Exception—Certain inch-pound values given in parentheses are provided for information only.  
1.4 This standard is currently written to accommodate only C(T) specimens.  
1.5 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.  
1.6 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: 30-Nov-2021
• ICS: 77.120.10 - Aluminium and aluminium alloys
• Technical Committee: B07 - Light Metals and Alloys
• Drafting Committee: B07.05 - Testing

Relations

• Refers: ASTM E1823-24a - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 15-Feb-2024
• Refers: ASTM E1823-24 - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 01-Feb-2024
• Refers: ASTM E1823-20 - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 01-Feb-2020
• Refers: ASTM B646-19 - Standard Practice for Fracture Toughness Testing of Aluminum Alloys
• Effective Date: 01-Nov-2019
• Refers: ASTM E561-19 - Standard Test Method for <emph type="bdit">K<inf>R</inf></emph> Curve Determination
• Effective Date: 15-Jul-2019
• Refers: ASTM E561-19e1 - Standard Test Method for <emph type="bdit">K<inf>R</inf></emph> Curve Determination
• Effective Date: 15-Jul-2019
• Refers: ASTM B646-17 - Standard Practice for Fracture Toughness Testing of Aluminum Alloys
• Effective Date: 01-Aug-2017
• Refers: ASTM E561-15a - Standard Test Method for <emph type="bdit">K<inf>R</inf></emph> Curve Determination
• Effective Date: 01-Dec-2015
• Refers: ASTM E561-15 - Standard Test Method for <emph type="bdit">K<inf>R</inf></emph> Curve Determination
• Effective Date: 15-Oct-2015
• Refers: ASTM E1823-12e - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 15-Dec-2012
• Refers: ASTM E399-12e3 - Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness K<inf>Ic</inf > of Metallic Materials
• Effective Date: 15-Nov-2012
• Refers: ASTM E399-12e1 - Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness K<inf>Ic</inf > of Metallic Materials
• Effective Date: 15-Nov-2012
• Refers: ASTM E1823-12d - Standard Terminology Relating to Fatigue and Fracture Testing
• Effective Date: 15-Nov-2012
• Refers: ASTM E399-12 - Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness <emph type="bdit" >K<inf> Ic</inf></emph> of Metallic Materials
• Effective Date: 15-Nov-2012
• Refers: ASTM E399-12e2 - Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness K<inf>Ic</inf > of Metallic Materials
• Effective Date: 15-Nov-2012

Overview

ASTM B645-21 is the internationally recognized standard practice for linear-elastic plane-strain fracture toughness testing of aluminum alloys. Developed by ASTM International’s Committee B07 on Light Metals and Alloys, this standard provides supplementary guidelines to Test Method E399, specifically addressing scenarios where it is not possible or practical to obtain fully valid plane-strain fracture toughness data. Its primary application is in quality assurance and material release determinations for aluminum alloy products, ensuring material lots meet specified fracture toughness requirements even when testing conditions vary.

Key Topics

• Supplement to Test Method E399: ASTM B645-21 builds on the established E399 method for plane-strain fracture toughness testing, adding clear procedures for handling invalid test data in quality assurance applications.
• Applicability: The practice covers all aluminum alloys, tempers, and product forms (plates, forgings, extrusions, rods), and is particularly useful when deciding if material lots satisfy specification criteria for fracture toughness.
• Specimen Sampling & Configuration:
  • Guidelines on sampling locations for various aluminum product forms.
  • Recommendations and requirements for specimen size selection, width, thickness, and configuration based on product constraints.
• Interpretation of Invalid Test Results: Provides a structured process to assess and, where appropriate, use certain invalid fracture toughness (K_Q) values for lot release, provided specified secondary conditions are satisfied.
• Reporting and Retesting: Detailed requirements for documentation and procedures for retesting in case of non-conforming results or invalid tests.
• Safety Considerations: Reminds users to establish appropriate safety, health, and environmental practices according to their specific testing context.

Applications

ASTM B645-21 is widely used in the aluminum manufacturing industry for:

• Quality Assurance Testing: Ensuring that aluminum alloy products meet customer and specification requirements for fracture toughness before shipment or material release.
• Material Qualification: Supporting manufacturers and purchasers in verifying that individual material lots possess sufficient resistance to crack propagation, even when full validity requirements per E399 cannot be met due to dimensional or material constraints.
• Product Specification Compliance: Providing supplementary procedures to validate and document material suitability, particularly where high fracture toughness or limited product dimensions complicate standard testing.
• Production Environments: Maximizing specimen size and adjusting test conditions to accommodate available material dimensions without compromising the integrity of lot release decisions.

By following ASTM B645-21, material producers and quality assurance professionals can make informed decisions about accepting or rejecting aluminum product lots, thus reducing risk and maintaining compliance with industry standards.

Related Standards

• ASTM E399 - Test Method for Linear-Elastic Plane-Strain Fracture Toughness of Metallic Materials: The foundational method referenced and supplemented by ASTM B645-21.
• ASTM B646 - Practice for Fracture Toughness Testing of Aluminum Alloys: Additional guidance for specific fracture toughness testing procedures.
• ASTM E29 - Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications: For rounding and reporting test results.
• ASTM E561 - Test Method for K Curve Determination: Methods for determining resistance curves in fracture mechanics.
• ASTM E1823 - Terminology Relating to Fatigue and Fracture Testing: Definitions and standard terminology used throughout ASTM fracture toughness standards.

Keywords: ASTM B645-21, aluminum alloys, fracture toughness, plane-strain, quality assurance, material release, K_Q values, invalid test results, ASTM E399, mechanical testing standards.

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: B645 − 21
Standard Practice for
Linear-Elastic Plane-Strain Fracture Toughness Testing of
Aluminum Alloys
This standard is issued under the fixed designation B645; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
Linear-elastic plane-strain fracture toughness testing of aluminum alloys is performed essentially in
accordance with Test Method E399. However, there is a need, in the application of Test Method E399
for quality assurance testing, to deal with the interpretation of the results for material qualification and
release in cases where all requirements for valid measurements of plane-strain fracture toughness
cannot be met. It is the purpose of this practice to provide consistent methods of dealing with those
situations.
1. Scope* priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This practice is applicable to the fracture toughness
1.6 This international standard was developed in accor-
testing of all aluminum alloys, tempers, and products, espe-
dance with internationally recognized principles on standard-
cially in cases where the tests are being made to establish
ization established in the Decision on Principles for the
whether or not individual lots meet the requirements of
Development of International Standards, Guides and Recom-
specifications and should be released to customers.
mendations issued by the World Trade Organization Technical
1.2 TestMethodE399isthebasictestmethodtobeusedfor
Barriers to Trade (TBT) Committee.
plane-strainfracturetoughnesstestingofaluminumalloys.The
purpose of this practice is to provide supplementary informa-
2. Referenced Documents
tion for plane-strain fracture toughness of aluminum alloys in
2.1 ASTM Standards:
three main areas:
B646 Practice for Fracture Toughness Testing of Aluminum
1.2.1 Specimen sampling,
Alloys
1.2.2 Specimen size selection, and
E29 Practice for Using Significant Digits in Test Data to
1.2.3 Interpretation of invalid test results.
Determine Conformance with Specifications
1.3 The values stated in SI units are to be regarded as
E399 Test Method for Linear-Elastic Plane-Strain Fracture
standard. No other units of measurement are included in this
Toughness of Metallic Materials
standard.
E561 Test Method forK Curve Determination
R
1.3.1 Exception—Certain inch-pound values given in paren-
E1823 TerminologyRelatingtoFatigueandFractureTesting
theses are provided for information only.
1.4 This standard is currently written to accommodate only 3. Terminology
C(T) specimens.
3.1 General—Terms, definitions, symbols, and orientation
1.5 This standard does not purport to address all of the
designations in Test Method E399 and Terminology E1823 are
safety concerns, if any, associated with its use. It is the
applicable herein.
responsibility of the user of this standard to establish appro-
3.2 Definitions:The following additional definitions are ap-
plicable:
This practice is under the jurisdiction of ASTM Committee B07 on Light
Metals and Alloys and is the direct responsibility of Subcommittee B07.05 on
Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2021. Published January 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1978. Last previous edition approved in 2015 as B645 – 10 (2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/B0645-21. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B645 − 21
3.2.1 invalid plane-strain fracture toughness—test result, 7.1.2 Specimens from forgings, extrusions, and rod shall be
K ,thatdoesnotmeetoneormoreofthevalidityrequirements taken from the center of the cross section as far as is practical.
Q
in Test Method E399 and, where so characterized, is of no
NOTE 1—Considerable care should be taken in specifying the location
value in judging the true plane-strain fracture toughness of a
of specimens within the thickness of the thick plate, forgings, extrusions,
material but may, under certain conditions, adequately guaran-
or rod because fracture toughness may vary appreciably with location
through the thickness.
tee the material’s fracture toughness for lot release purposes.
3.2.2 valid plane-strain, fracture toughness—test result
8. Test Specimen Configuration and Dimensions
meetingallthevalidityrequirementsinTestMethodE399,that
8.1 Specimen size requirements stated in the individual
is, a value of K .
Ic
material specifications shall be followed. In the absence of
4. Summary of Practice
specific requirements, the specimen types, general
configuration, and size requirements in Test Method E399 are
4.1 This practice supplements Test Method E399 and Prac-
applicable herein with the following supplemental recommen-
tice B646 in three main areas:
dations and requirements:
4.1.1 Specimen sampling,
8.1.1 For aluminum products, the recommended minimum
4.1.2 Specimen size selection, and
specimen ligament length is:
4.1.3 Interpretation of results that fail the validity require-
ments in Test Method E399 in one of the following areas in
K
Q
W 2 a $5· (1)
~ ! S D
order to determine if the invalid results are usable for lot
σ
YS
release: rather than the required minimum of:
4.1.3.1 P /P requirements, 2
max Q
K
Q
~W 2 a!$ 2.5· (2)
4.1.3.2 Specimen size requirements, and S D
σ
YS
4.1.3.3 Fatigue precracking requirements.
in Test Method E399.
NOTE 2—Experimental studies have shown that more uniform values
5. Significance and Use
of K are obtained for high toughness aluminum alloys when the
Q
conditions of Eq 1 are met.
5.1 This practice for plane-strain fracture toughness testing
of aluminum alloys may be used as a supplement to Test 8.1.2 In all cases, the specimen W/B ratio shall be greater
Method E399. The application of this practice is primarily than or equal to 2 and less than or equal to 4 based on nominal
intended for quality assurance and material release in cases specimen dimensions. Other specimen dimensional propor-
where valid plane-strain fracture toughness data cannot be tions in Test Method E399 shall also be maintained.
obtained per Test Method E399.
NOTE 3—Specimens meeting this requirement correspond to the stan-
dard (W/B = 2) or alternative specimen geometries (2 ≤ W/B ≤ 4) in Test
5.2 It must be understood that the interpretations and
Method E399.
guidelines in this practice do not alter the validity requirements
of Test Method E399 or promote the designation of data that 8.1.3 When the minimum size requirement of:
are invalid according to Test Method E399 to a “valid”
K
Q
~W 2 a!$ 2.5· (3)
condition. This practice is primarily concerned with cases S D
σ
YS
where it is not possible or practical to obtain valid data, but
in Test Method E399 cannot be met due to product dimen-
where material release judgments must be made against
sional constraints, the specimen shall be machined such that
specified fracture toughness values. Where it is possible to
the W dimension is maximized to the nearest 12.7 mm (0.5
obtain a valid plane-strain fracture toughness value by replace-
in.) at the specified test location while still meeting the re-
ment testing according to Test Method E399, that is the
quirements of 8.1.2 up to the specimen width required in the
preferred approach.
applicable material specification, or if no width is specified,
up to an upper required limit of 127 mm (5.0 in.).
6. Apparatus
NOTE 4—It is not practical for W to vary continuously (that is,
non-discretely) since many C(T) specimen dimensions are proportional to
6.1 All apparatus shall be in conformance withTest Method
W. Each change in W requires a different machining or testing setup.
E399.
Therefore, it is required that W be maximized to the nearest 12.7 mm (0.5
in.).
7. Sampling
8.1.4 When the requirement of:
7.1 Sampling requirements stated in the individual material
P
specifications shall be followed. In the absence of specific
max
# 1.10 (4)
requirements in the individual material specifications, speci- P
Q
cannot be met due to product dimensional constraints, the
mens shall be taken at the following locations:
specimen shall be machined such that the B dimension is
7.1.1 Specimens from plate shall be from the mid-thickness,
maximized up to a required maximum thickness of 63.5 mm
until the plate thickness is twice the standard specimen
(2.5 in.) at the specified test location. The specimen ligament
thickness for that particular product (that is, the specimen
thickness selected for lot release and quality assurance testing
which typically yields a valid K for that particular alloy and
Ic 3
Kaufman, J. G., “Experience in Plane Strain Fracture Toughness per ASTM
product), at and beyond which the specimen shall be centered
E399,” Developments in Fracture Mechanics Test Methods Standardization, ASTM
at the quarter-thickness location. STP 632, ASTM, 1977, pp. 3-24.
B645 − 21
length should be maintained at:
usable for lot release purposes if all of the appropriate
requirements in this section are met.
K
Q
~W 2 a!$ 2.5· (5)
S D
σ
YS
11.2 A K value that has invalidities in accordance withTest
Q
or as large as possible while still meeting the requirements
Method E399, but which meets the specimen width and
of 8.1.2, up to the specimen width required in the applicable
thickness requirements in the individual material specification,
material specification, or
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B645 − 10 (Reapproved 2015) B645 − 21
Standard Practice for
Linear-Elastic Plane–StrainPlane-Strain Fracture Toughness
Testing of Aluminum Alloys
This standard is issued under the fixed designation B645; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
Linear-elastic plane-strain fracture toughness testing of aluminum alloys is performed essentially in
accordance with Test Method E399. However, there is a need, in the application of Test Method E399
for quality assurance testing, to deal with the interpretation of the results for material qualification and
release in cases where all requirements for valid measurements of plane-strain fracture toughness
cannot be met. It is the purpose of this practice to provide consistent methods of dealing with those
situations.
1. Scope*
1.1 This practice is applicable to the fracture toughness testing of all aluminum alloys, tempers, and products, especially in cases
where the tests are being made to establish whether or not individual lots meet the requirements of specifications and should be
released to customers.
1.2 Test Method E399 is the basic test method to be used for plane-strain fracture toughness testing of aluminum alloys. The
purpose of this practice is to provide supplementary information for plane-strain fracture toughness of aluminum alloys in three
main areas:
1.2.1 Specimen sampling,
1.2.2 Specimen size selection, and
1.2.3 Interpretation of invalid test results.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Exception—Certain inch-pound values given in parentheses are provided for information only.
1.4 This standard is currently written to accommodate only C(T) specimens.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
This practice is under the jurisdiction of ASTM Committee B07 on Light Metals and Alloys and is the direct responsibility of Subcommittee B07.05 on Testing.
Current edition approved Dec. 1, 2015Dec. 1, 2021. Published December 2015January 2022. Originally approved in 1978. Last previous edition approved in 20102015
as B645 – 10.B645 – 10 (2015). DOI: 10.1520/B0645-10R15.10.1520/B0645-21.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B645 − 21
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
B646 Practice for Fracture Toughness Testing of Aluminum Alloys
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness of Metallic Materials
E561 Test Method forK Curve Determination
R
E1823 Terminology Relating to Fatigue and Fracture Testing
3. Terminology
3.1 General—Terms, definitions, symbols, and orientation designations in Test Method E399 and Terminology E1823 are
applicable herein.
3.2 Definitions:The following additional definitions are applicable:
3.2.1 invalid plane-strain fracture toughness—test result, K , that does not meet one or more of the validity requirements in Test
Q
Method E399 and, where so characterized, is of no value in judging the true plain-strainplane-strain fracture toughness of a
material but may, under certain conditions, adequately guarantee the material’s fracture toughness for lot release purposes.
3.2.2 valid plane-strain, fracture toughness—test result meeting all the validity requirements in Test Method E399, that is, a value
of K .
Ic
4. Summary of Practice
4.1 This practice supplements Test Method E399 and Practice B646 in three main areas:
4.1.1 Specimen sampling,
4.1.2 Specimen size selection, and
4.1.3 Interpretation of results that fail the validity requirements in Test Method E399 in one of the following areas in order to
determine if the invalid results are usable for lot release:
4.1.3.1 P /P requirements,
max Q
4.1.3.2 Specimen size requirements, and
4.1.3.3 Fatigue precracking requirements.
5. Significance and Use
5.1 This practice for plane-strain fracture toughness testing of aluminum alloys may be used as a supplement to Test Method E399.
The application of this practice is primarily intended for quality assurance and material release in cases where valid plane-strain
fracture toughness data cannot be obtained per Test Method E399.
5.2 It must be understood that the interpretations and guidelines in this practice do not alter the validity requirements of Test
Method E399 or promote the designation of data that are invalid according to Test Method E399 to a “valid” condition. This
practice is primarily concerned with cases where it is not possible or practical to obtain valid data, but where material release
judgments must be made against specified fracture toughness values. Where it is possible to obtain a valid plane-strain fracture
toughness value by replacement testing according to Test Method E399, that is the preferred approach.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
B645 − 21
6. Apparatus
6.1 All apparatus shall be in conformance with Test Method E399.
7. Sampling
7.1 Sampling requirements stated in the individual material specifications shall be followed. In the absence of specific
requirements in the individual material specifications, specimens shall be taken at the following locations:
7.1.1 Specimens from plate shall be from the mid-thickness, until the plate thickness is twice the standard specimen thickness for
that particular product (that is, the specimen thickness selected for lot release and quality assurance testing which typically yields
a valid K for that particular alloy and product), at and beyond which the specimen shall be centered at the quarter-thickness
Ic
location.
7.1.2 Specimens from forgings, extrusions, and rod shall be taken from the center of the cross section as far as is practical.
NOTE 1—Considerable care should be taken in specifying the location of specimens within the thickness of the thick plate, forgings, extrusions, or rod
because fracture toughness may vary appreciably with location through the thickness.
8. Test Specimen Configuration and Dimensions
8.1 Specimen size requirements stated in the individual material specifications shall be followed. In the absence of specific
requirements, the specimen types, general configuration, and size requirements in Test Method E399 are applicable herein with the
following supplemental recommendations and requirements:
8.1.1 For aluminum products, the recommended minimum specimen ligament length is:
K
Q
W 2 a $ 5· (1)
~ ! S D
σ
YS
rather than the required minimum of:
K
Q
W 2 a $ 2.5· (2)
~ ! S D
σ
YS
in Test Method E399.
NOTE 2—Experimental studies have shown that more uniform values of K are obtained for high toughness aluminum alloys when the conditions of Eq
Q
1 are met.
8.1.2 In all cases, the specimen W/B ratio shall be greater than or equal to 2 and less than or equal to 4 based on nominal specimen
dimensions. Other specimen dimensional proportions in Test Method E399 shall also be maintained.
NOTE 3—Specimens meeting this requirement correspond to the standard (W/B = 2) or alternative specimen geometries (2 ≤ W/B ≤ 4) in Test Method
E399.
8.1.3 When the minimum size requirement of:
K
Q
W 2 a $ 2.5· (3)
~ ! S D
σ
YS
in Test Method E399 cannot be met due to product dimensional constraints, the specimen shall be machined such that the W
dimension is maximized to the nearest 12.7 mm (0.5 in.) at the specified test location while still meeting the requirements of
8.1.2 up to the specimen width required in the applicable material specification, or if no width is specified, up to an upper
required limit of 127 mm (5.0 in.).
NOTE 4—It is not practical for W to vary continuously (that is, non-discretely) since many C(T) specimen dimensions are proportional to W. Each change
in W requires a different machining or testing setup. Therefore, it is required that W be maximized to the nearest 12.7 mm (0.5 in.).
8.1.4 When the requirement Pof:
max
/P
Kaufman, J. G., “Experience in Plane Strain Fracture Toughness per ASTM E399,” Developments in Fracture Mechanics Test Methods Standardization, ASTM STP 632,
ASTM, 1977, pp. 3-24.
B645 − 21
P
max
# 1.10 (4)
P
Q
Q
≤ 1.1 cannot be met due to product dimensional constraints, the specimen shall be machined such that the B dimension is
maximized up to a required maximum thickness of 63.5 mm (2.5 in.) at the specified test location. The specimen ligament
length should be maintained at:
K
Q
W 2 a $ 2.5· (5)
~ ! S D
σ
YS
or as large as possible while still meeting the requirements of 8.1.2, up to the specimen width required in the applicable mate-
rial specification, or if no width is specified, up to an upper required limit of 127 mm (5.0 in.).
NOTE 5—The upper limit on specimen thickness and width have been established because of practical limitations on how large a specimen can be routinely
machined and tested for lot release purposes in a production environment using standard equipment. The producer may test thicker and/or wider
specimens provided the testing capability and sufficient material are available, and the specimen proportions adhere to the requirements in 8.1.2.
8.1.5 When it is not possible to meet either the:
K
Q
~W 2 a! $ 2.5· (6)
S D
σ
YS
or the:
P
max
# 1.1 (7)
P
Q
P
max
# 1.10 (7)
P
Q
requirements, then both the W and B dimensions shall be maximized in accordance with requirements in 8.1.2, 8.1.3, and
8.1.4.
NOTE 6—For aluminum products where the size requirement in either
...