ASTM B646-06a
(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 E 399 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.
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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Standards Content (Sample)
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Designation:B646–06a
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.Anumber 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* B557 Test Methods for Tension Testing Wrought and Cast
Aluminum- and Magnesium-Alloy Products
1.1 Fracture toughness is a key property for a number of
B645 Practice for Linear-Elastic Plane−Strain Fracture
aluminum alloys utilized in aerospace and process industries.
Toughness Testing of Aluminum Alloys
Fracture toughness testing is often required for supplier quali-
E338 TestMethodofSharp-NotchTensionTestingofHigh-
fication, quality control, and material release purposes. The
Strength Sheet Materials
purpose of this practice is to provide uniform test procedures
E399 Test Method for Linear-Elastic Plane-Strain Fracture
for the industry, pointing out which current standards are
Toughness K of Metallic Materials
utilized in specific cases, and providing guidelines where no Ic
E561 Test Method for K-R Curve Determination
standards exist. This practice provides guidance for testing (a)
E602 Test Method for Sharp-Notch Tension Testing with
sheet and other products having a specified thickness less than
Cylindrical Specimens
6.35 mm (0.250 in.), (b) intermediate thicknesses of plate,
E1304 TestMethodforPlane-Strain(Chevron-Notch)Frac-
forgings, and extrusions that are too thin for valid plane-strain
ture Toughness of Metallic Materials
fracture toughness testing but too thick for treatment as sheet,
E1823 Terminology Relating to Fatigue and Fracture Test-
such as products having a specified thickness greater than or
ing
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
3. Terminology
products where Test Method E399 is applicable.
3.1 The terminology and definitions in the referenced docu-
1.2 This practice addresses both direct measurements of
ments, especially E1823, are applicable to this practice.
fracture toughness and screening tests, the latter recognizing
3.2 Definitions of Terms Specific to This Standard:
the complexity and expense of making formal fracture tough-
3.2.1 For purposes of this practice, the following descrip-
ness measurements on great quantities of production lots.
tions of terms are applicable in conjunction with Test Method
1.3 The values stated in SI units are to be regarded as the
E561:
standard. The values in inch-pound units given in parenthesis
3.2.2 CMOD—crack mouth opening displacement; the
are provided for information purposes only.
measurement of specimen displacement between two points
1.4 This standard does not purport to address all of the
spanning the machined notch at locations specific to the
safety concerns, if any, associated with its use. It is the
specimen being tested.
responsibility of the user of this standard to establish appro-
3.2.3 K —avalueofK ontheK-Rcurvebasedona25%
R25 R
priate safety and health practices and determine the applica-
secant intercept of the force-CMOD test record from a C(T)
bility of regulatory limitations prior to use.
specimen and the effective crack length a at that point that
e
2. Referenced Documents otherwise satisfies the remaining-ligament criterion of Test
2
Method E561. If the maximum force is reached prior to the
2.1 ASTM Standards:
25% secant intercept point, the maximum force point shall be
used instead to determine the K value.
R25
1
This practice is under the jurisdiction of ASTM Committee B07 on Light
3.2.4 K —for the purpose of this practice, K is the critical
c c
Metals and Alloys, and is the direct responsibility of Subcommittee B07.05 on
stressintensityfactorbasedonthemaximumforcevalueofthe
Testing.
force-CMOD test record from an M(T) specimen and the
Current edition approved Sept. 1, 2006. Published September 2006. Originally
effective crack length, a , at that point that otherwise satisfies
approved in 1978. Last previous edition approved in 2006 as B646–06. DOI:
e
10.1520/B0646-06A.
the remaining-ligament criterion of Test Method E561.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.5 K (also commonly designated K )—the apparent
app co
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
plane stress fracture toughness based on the original crack
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. length, a , and the maximum force value of the force-CMOD
o
*A Summary of Ch
...
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