ASTM B646-03
(Practice)Standard Practice for Fracture Toughness Testing of Aluminum Alloys
Standard Practice for Fracture Toughness Testing of Aluminum Alloys
SCOPE
1.1 This practice provides guidance for testing (a) thin products, of thicknesses equivalent to sheet that is, (1] 0.249 in. (6.30 mm)), (2) intermediate thicknesses of plate, forgings, and extrusions, too thin for valid plane-strain fracture toughness testing but too thick for treatment as sheet, that is over 0.249 in. (6.30 mm) and up to 1 to 2 in. (25 to 50 mm), dependent upon toughness level, and (3) relatively thick products where Test Method E399 is applicable. For changes to this specification since the last issue, refer to the Summary of Changes section at the end of the standard.
1.2 This practice addresses the problem of screening tests, recognizing the complexity and expense of making formal fracture toughness measurements on great quantities of production lots, and provides alternatives in the form of simpler, less expensive tests that may be carried out either in a research or production test laboratory.
1.3 The values stated in inch-pound units are to be regarded as the standard.
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: B 646 – 03
Standard Practice for
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Fracture Toughness Testing of Aluminum Alloys
This standard is issued under the fixed designation B 646; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
INTRODUCTION
Fracture toughness is a key property for a number of aluminum alloys utilized in aerospace and
process industries, but at the current stage of development of fracture test techniques no standard
methods exist to cover a number of the product lines or dimensional ranges involved. Plane-strain
fracture toughness, K , is a keystone of the industry, but for the very tough alloys of principal interest,
Ic
valid measurements can be made only for relatively thick sections. Thus it is necessary to provide this
standard practice for uniform quality control test procedures for the industry, pointing out which
current standards are utilized in specific cases, and providing guidelines where no standards exist.
1. Scope* B 557 Test Methods of Tension Testing Wrought and Cast
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Aluminum- and Magnesium-Alloy Products
1.1 This practice covers guidance for testing (1) thin prod-
B 645 Practice for Plane Strain Fracture Toughness Testing
ucts, of thicknesses equivalent to sheet that is, (0.249 in. (6.30
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of Aluminum Alloys
mm)), (2) intermediate thicknesses of plate, forgings, and
E 23 Test Methods for Notched Bar Impact Testing of
extrusions too thin for valid plane-strain fracture toughness
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Metallic Materials
testing but too thick for treatment as sheet, that is over 0.249 in.
E 338 Test Method of Sharp-Notch Tension Testing of
(6.30 mm) and up to 1 to 2 in. (25 to 50 mm), dependent upon
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High-Strength Sheet Materials
toughness level, and (3) relatively thick products where Test
E 399 Test Method for Plane-Strain Fracture Toughness of
Method E 399 is applicable. For changes to this specification
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Metallic Materials
since the last issue, refer to the Summary of Changes section at
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E 561 Practice for R-Curve Determination
the end of the standard.
E 602 Test Method for Sharp-Notch Tension Testing with
1.2 This practice addresses the problem of screening tests,
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Cylindrical Specimens
recognizing the complexity and expense of making formal
E 1304 Test Method for Plane-Strain (Chevron Notch)
fracture toughness measurements on great quantities of pro-
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Fracture Toughness of Metallic Materials
duction lots, and provides alternatives in the form of simpler,
E 1823 Terminology Relating to Fatigue and Fracture Test-
less expensive tests that may be carried out either in a research
3
ing
or production test laboratory.
2.2 Other Document:
1.3 The values stated in inch-pound units are to be regarded
Aluminum Association Bulletin T5, “Fracture Toughness
as the standard.
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Testing of Aluminum Alloys”
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 The terminology and definitions in the referenced docu-
priate safety and health practices and determine the applica-
ments are applicable to this practice.
bility of regulatory limitations prior to use.
3.2 Definitions of Terms Specific to This Standard:
2. Referenced Documents 3.2.1 For purposes of this practice, the following descrip-
tions of terms are applicable in conjunction with Practice E 561
2.1 ASTM Standards:
and use of the compact specimen:
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This practice is under the jurisdiction of ASTM Committee B07 on Light
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Metals and Alloys, and is the direct responsibility of Subcommittee B07.05 on Annual Book of ASTM Standards, Vol 02.02.
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Testing. Annual Book of ASTM Standards, Vol 03.01.
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Current edition approved Sept. 10, 2003. Published September 2003. Originally Available from The Aluminum Association, 750 3rd Ave., New York, NY
approved in 1978. Last previous edition approved in 1997 as B 646 – 97. 10017.
*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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B646–03
3.2.2 K —A value of K on the R-curve based on a 25 % is recommended for measurement of critical stress intensity
R
25
secant intercept of the force-crack opening displacement test factor (K ) when tested in accordance with Practice E 561, as
c
record and the effective crack length at that point that otherwise described in 7.2.
satisfies the remaining-ligament criterion of Practice E
...
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