ASTM B646-19
(Practice)Standard Practice for Fracture Toughness Testing of Aluminum Alloys
Standard Practice for Fracture Toughness Testing of Aluminum Alloys
SIGNIFICANCE AND USE
5.1 This practice is provided to develop and maintain uniformity in practices for the evaluation of the toughness of aluminum alloys, particularly with regard to supplier qualification, quality assurance, and material release to specifications.
5.2 It is emphasized that the use of these procedures will not alter the validity of data determined with specific test methods, but provides guidance in the interpretation of test results (valid or invalid) and guidance in the selection of a reasonable test procedure in those instances where no standard exists today.
SCOPE
1.1 Fracture toughness is a key property for a number of aluminum alloys utilized in aerospace and process industries. Fracture toughness testing is often required for supplier qualification, quality control, and material release purposes. The purpose of this practice is to provide uniform test procedures for the industry, pointing out which current standards are utilized in specific cases, and providing guidelines where no standards exist. This practice provides guidance for testing (a) sheet and other products having a specified thickness less than 6.35 mm (0.250 in.), (b) intermediate thicknesses of plate, forgings, and extrusions that are too thin for valid plane-strain fracture toughness testing but too thick for treatment as sheet, such as products having a specified thickness greater than or equal to 6.35 mm (0.250 in.) but less than 25 to 50 mm (1 to 2 in.), depending on toughness level, and (c) relatively thick products where Test Method E399 is applicable.
1.2 The values stated in SI units are to be regarded as the standard. The values in inch-pound units given in parenthesis are provided for information purposes only.
1.3 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.
1.4 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.
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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: B646 − 19
Standard Practice for
1
Fracture Toughness Testing of Aluminum Alloys
This standard is issued under the fixed designation B646; 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.
1. Scope* 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 Fracture toughness is a key property for a number of
B557 Test Methods for Tension Testing Wrought and Cast
aluminum alloys utilized in aerospace and process industries.
Aluminum- and Magnesium-Alloy Products
Fracture toughness testing is often required for supplier
B557M Test Methods for Tension Testing Wrought and Cast
qualification, quality control, and material release purposes.
Aluminum- and Magnesium-Alloy Products (Metric)
The purpose of this practice is to provide uniform test
B645 Practice for Linear-Elastic Plane–Strain Fracture
procedures for the industry, pointing out which current stan-
Toughness Testing of Aluminum Alloys
dards are utilized in specific cases, and providing guidelines
E399 Test Method for Linear-Elastic Plane-Strain Fracture
where no standards exist. This practice provides guidance for
Toughness K of Metallic Materials
testing (a) sheet and other products having a specified thick-
Ic
E561 Test Method forK Curve Determination
nesslessthan6.35 mm(0.250in.),(b)intermediatethicknesses
R
E1304 Test Method for Plane-Strain (Chevron-Notch) Frac-
of plate, forgings, and extrusions that are too thin for valid
ture Toughness of Metallic Materials
plane-strain fracture toughness testing but too thick for treat-
E1823 TerminologyRelatingtoFatigueandFractureTesting
ment as sheet, such as products having a specified thickness
greater than or equal to 6.35 mm (0.250 in.) but less than 25 to
3. Terminology
50 mm (1 to 2 in.), depending on toughness level, and (c)
relatively thick products where Test Method E399 is appli-
3.1 The terminology and definitions in the referenced
cable.
documents, especially E1823, are applicable to this practice.
1.2 The values stated in SI units are to be regarded as the
3.2 Definitions of Terms Specific to This Standard:
standard. The values in inch-pound units given in parenthesis
3.2.1 For purposes of this practice, the following descrip-
are provided for information purposes only.
tions of terms are applicable in conjunction with Test Method
E561:
1.3 This standard does not purport to address all of the
3.2.2 K —a value of K on the K curve based on a 25 %
safety concerns, if any, associated with its use. It is the R25 R R
secant intercept of the force-CMOD test record from a C(T)
responsibility of the user of this standard to establish appro-
specimen and the effective crack size a at that point that
priate safety, health, and environmental practices and deter- e
otherwise satisfies the remaining-ligament criterion of Test
mine the applicability of regulatory limitations prior to use.
Method E561. If the maximum force is reached prior to the
1.4 This international standard was developed in accor-
25 % secant intercept point, the maximum force point shall be
dance with internationally recognized principles on standard-
used instead to determine the K value.
R25
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.2.3 K —for the purpose of this practice, K is the critical
c c
stressintensityfactorbasedonthemaximumforcevalueofthe
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. force-CMOD test record and the effective crack size, a , at that
e
point that otherwise satisfies the remaining-ligament criterion
of Test Method E561.
1
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
2
Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2019. Published November 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1978. Last previous edition approved in 2017 as B646 – 17. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0646-19. 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
...
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: B646 − 17 B646 − 19
Standard Practice for
1
Fracture Toughness Testing of Aluminum Alloys
This standard is issued under the fixed designation B646; 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.
1. Scope*
1.1 Fracture toughness is a key property for a number of aluminum alloys utilized in aerospace and process industries. Fracture
toughness testing is often required for supplier qualification, quality control, and material release purposes. The purpose of this
practice is to provide uniform test procedures for the industry, pointing out which current standards are utilized in specific cases,
and providing guidelines where no standards exist. This practice provides guidance for testing (a) sheet and other products having
a specified thickness less than 6.35 mm 6.35 mm (0.250 in.), (b) intermediate thicknesses of plate, forgings, and extrusions that
are too thin for valid plane-strain fracture toughness testing but too thick for treatment as sheet, such as products having a specified
thickness greater than or equal to 6.35 mm (0.250 in.) but less than 25 to 50 mm (1 to 2 in.), depending on toughness level, and
(c) relatively thick products where Test Method E399 is applicable.
1.2 This practice addresses both direct measurements of fracture toughness and screening tests, the latter recognizing the
complexity and expense of making formal fracture toughness measurements on great quantities of production lots.
1.2 The values stated in SI units are to be regarded as the standard. The values in inch-pound units given in parenthesis are
provided for information purposes only.
1.3 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.
1.4 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
2.1 ASTM Standards:
B557 Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products
B557M Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products (Metric)
B645 Practice for Linear-Elastic Plane–Strain Fracture Toughness Testing of Aluminum Alloys
E399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness K of Metallic Materials
Ic
E561 Test Method forK Curve Determination
R
E1304 Test Method for Plane-Strain (Chevron-Notch) Fracture Toughness of Metallic Materials
E1823 Terminology Relating to Fatigue and Fracture Testing
3. Terminology
3.1 The terminology and definitions in the referenced documents, especially E1823, are applicable to this practice.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 For purposes of this practice, the following descriptions of terms are applicable in conjunction with Test Method E561:
3.2.2 CMOD—crack mouth opening displacement; the measurement of specimen displacement between two points spanning the
machined notch at locations specific to the specimen being tested.
1
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 Aug. 1, 2017Nov. 1, 2019. Published August 2017November 2019. Originally approved in 1978. Last previous edition approved in 20122017
as B646 – 12.B646 – 17. DOI: 10.1520/B0646-17.10.1520/B0646-19.
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 Standards
volume information, refer to the standard’s Document Summary page on 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
1
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