ASTM B646-12
(Practice)Standard Practice for Fracture Toughness Testing of Aluminum Alloys
Standard Practice for Fracture Toughness Testing of Aluminum Alloys
SIGNIFICANCE AND USE
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.
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 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.
1.3 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.
1.4 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.
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Designation: B646 − 12
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 Department of Defense.
1. Scope* 2. Referenced Documents
2
1.1 Fracture toughness is a key property for a number of 2.1 ASTM Standards:
aluminum alloys utilized in aerospace and process industries. B557 Test Methods for Tension Testing Wrought and Cast
Fracture toughness testing is often required for supplier Aluminum- and Magnesium-Alloy Products
qualification, quality control, and material release purposes. B557M Test Methods for Tension Testing Wrought and Cast
The purpose of this practice is to provide uniform test Aluminum- and Magnesium-Alloy Products (Metric)
procedures for the industry, pointing out which current stan- B645 Practice for Linear-Elastic Plane–Strain Fracture
dards are utilized in specific cases, and providing guidelines Toughness Testing of Aluminum Alloys
where no standards exist. This practice provides guidance for E399 Test Method for Linear-Elastic Plane-Strain Fracture
testing (a) sheet and other products having a specified thick- Toughness K of Metallic Materials
Ic
nesslessthan6.35mm(0.250in.),(b)intermediatethicknesses E561 Test Method forK-R Curve Determination
of plate, forgings, and extrusions that are too thin for valid E1304 Test Method for Plane-Strain (Chevron-Notch) Frac-
plane-strain fracture toughness testing but too thick for treat- ture Toughness of Metallic Materials
ment as sheet, such as products having a specified thickness E1823 TerminologyRelatingtoFatigueandFractureTesting
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)
3.1 The terminology and definitions in the referenced
relatively thick products where Test Method E399 is appli-
documents, especially E1823, are applicable to this practice.
cable.
3.2 Definitions of Terms Specific to This Standard:
1.2 This practice addresses both direct measurements of
3.2.1 For purposes of this practice, the following descrip-
fracture toughness and screening tests, the latter recognizing
tions of terms are applicable in conjunction with Test Method
the complexity and expense of making formal fracture tough-
E561:
ness measurements on great quantities of production lots.
3.2.2 CMOD—crack mouth opening displacement; the mea-
1.3 The values stated in SI units are to be regarded as the
surement of specimen displacement between two points span-
standard. The values in inch-pound units given in parenthesis
ning the machined notch at locations specific to the specimen
are provided for information purposes only.
being tested.
1.4 This standard does not purport to address all of the
3.2.3 K —avalueof K onthe K-Rcurvebasedona25 %
R25 R
safety concerns, if any, associated with its use. It is the
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 length a at that point that
e
priate safety and health practices and determine the applica-
otherwise satisfies the remaining-ligament criterion of Test
bility of regulatory limitations prior to use.
Method E561. If the maximum force is reached prior to the
25 % secant intercept point, the maximum force point shall be
used instead to determine the K value.
1 R25
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 May 1, 2012. Published June 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1978. Last previous edition approved in 2006 as B646 – 06a. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0646-12. 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
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B646 − 12
3.2.4 K —for the purpose of this practice, K is the critical in general accordance withTest Method E561 as supplemented
c c
stressintensityfactorbasedonthemaximumforcevalueofthe by this practice in 7.1;or
force-CMOD test record from an M(T) specimen and the 6.2.2 Determine the K-R cur
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:B646–06a Designation:B646–12
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 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 (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.
1.3 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.
1.4 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.
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 PracticeforLinear-ElasticPlaneStrainFractureToughnessTestingofAluminumAlloysE338TestMethodofSharp-Notch
Tension Testing of High-
Strength Sheet Materials
E399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness K of Metallic Materials
Ic
E561 Test Method for K-R Curve Determination E602Test Method for Sharp-Notch Tension Testing with Cylindrical
Specimens
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.
3.2.3 K —a value of K on the K-R curve based on a 25 % secant intercept of the force-CMOD test record from a C(T)
R25 R
specimen and the effective crack length a at that point that otherwise satisfies the remaining-ligament criterion of Test Method
e
1
This practice is under the jurisdiction ofASTM Committee B07 on Light Metals andAlloys,Alloys and is the direct responsibility of Subcommittee B07.05 on Testing.
Current edition approved Sept.May 1, 2006.2012. Published September 2006.June 2012. Originally approved in 1978. Last previous edition approved in 2006 as
B646 – 06a. DOI: 10.1520/B0646-06A.10.1520/B0646-12.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM 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.
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