ASTM B909-00(2006)
(Guide)Standard Guide for Plane Strain Fracture Toughness Testing of Non-Stress Relieved Aluminum Products
Standard Guide for Plane Strain Fracture Toughness Testing of Non-Stress Relieved Aluminum Products
SCOPE
1.1 This guide covers supplementary guidelines for plane-strain fracture toughness testing of aluminum products for which complete stress relief is not practicable. Guidelines for recognizing when residual stresses may be significantly biasing test results are presented, as well as methods for minimizing the effects of residual stress during testing. This guide also provides guidelines for correction and interpretation of data produced during the testing of these products. Test Method E 399 is the standard test method to be used for plane-strain fracture toughness testing of aluminum alloys.
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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B909–00 (Reapproved 2006)
Standard Guide for
Plane Strain Fracture Toughness Testing of Non-Stress
Relieved Aluminum Products
This standard is issued under the fixed designation B909; 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.
1. Scope 3. Terminology
1.1 This guide covers supplementary guidelines for plane- 3.1 Definitions—Terminology in Test Method E399 and
strain fracture toughness testing of aluminum products for Terminology E1823 are applicable herein.
which complete stress relief is not practicable. Guidelines for 3.2 Definitions of Terms Specific to This Standard:
recognizingwhenresidualstressesmaybesignificantlybiasing 3.2.1 corrected plane-strain fracture toughness— a test
test results are presented, as well as methods for minimizing result, designated K (corrected), which has been corrected for
q
the effects of residual stress during testing. This guide also residual stress bias by one of the methods outlined in this
provides guidelines for correction and interpretation of data guide.ThecorrectedresultisanestimationoftheK orK that
q Ic
produced during the testing of these products. Test Method would have been obtained in a residual stress free specimen.
E399 is the standard test method to be used for plane-strain The corrected result may be obtained from a test record which
fracture toughness testing of aluminum alloys. yielded either an invalid K or valid K , but for which there is
q Ic
1.2 This standard does not purport to address all of the evidence that significant residual stress is present in the test
safety concerns, if any, associated with its use. It is the coupon.
responsibility of the user of this standard to establish appro- 3.2.2 invalid plane-strain fracture toughness— a test result,
priate safety and health practices and determine the applica- designated K , that does not meet one or more validity
q
bility of regulatory limitations prior to use. requirements in Test Method E399 or ISO 12737 and may or
may not be significantly influenced by residual stress.
2. Referenced Documents
3.2.3 valid plane-strain fracture toughness— a test result,
2.1 ASTM Standards:
designated K , meeting the validity requirements in Test
Ic
E399 Test Method for Linear-Elastic Plane-Strain Fracture
Method E399 or ISO 12737 that may or may not be signifi-
Toughness K of Metallic Materials cantly influenced by residual stress.
Ic
E561 Test Method for K-R Curve Determination
4. Significance and Use
E1823 Terminology Relating to Fatigue and Fracture Test-
ing 4.1 The property K , determined by Test Method E399 or
Ic
2.2 ANSI Standard: ISO 12737, characterizes a material’s resistance to fracture in
ANSI H35.1 Alloy and Temper Designations for Alumi- a neutral environment and in the presence of a sharp crack
num subjected to an applied opening force or moment within a field
2.3 ISO Standard: of high constraint to lateral plastic flow (plane strain condi-
ISO 12737 Metallic Materials–Determination of Plane tion).AK value is considered to be a lower limiting value of
Ic
Strain Fracture Toughness fracture toughness associated with the plane strain state.
4.1.1 Thermal quenching processes used with precipitation
hardened aluminum alloy products can introduce significant
This guide is under the jurisdiction ofASTM Committee B07 on Light Metals
residual stresses in the product. Mechanical stress relief pro-
and Alloys and is the direct responsibility of Subcommittee B07.05 on Testing.
cedures (stretching, compression) are commonly used to re-
Current edition approved Sept. 1, 2006. Published September 2006. Originally
approved in 2000. Last previous edition approved in 2000 as B909 – 00. DOI:
lieve these residual stresses in products with simple shapes.
10.1520/B0909-00R06.
However, in the case of mill products with thick cross-sections
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
(for example, heavy gage plate or large hand forgings) 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 complex shapes (for example, closed die forgings, complex
the ASTM website.
open die forgings, stepped extrusions, castings), complete
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
mechanical stress relief is not always possible. In other
4th Floor, New York, NY 10036, http://www.ansi.org.
instances residual stresses may be unintentionally introduced
Available from International Organization for Standardization (ISO), 1 rue de
Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B909–00 (2006)
into a product during fabrication operations such as straight- length to width ratio (a /W) of 0.45, a difference in the height
o
ening, forming, or welding operations. measured before and after machining the notch equal to or
4.1.2 Specimens taken from such products that contain greater than 0.003 in. (0.076 mm) is an indicator that the
residual stress will likewise themselves contain residual stress. ensuing test result will be significantly influenced by residual
While the act of specimen extraction in itself partially relieves stress.
and redistributes the pattern of original stress, the remaining 5.1.3 Excessive fatigue precrack front curvature not meet-
magnitude can still be appreciable enough to cause significant ing the crack-front straightness requirements in Test Method
error in the ensuing test result. E399 or ISO 12737.
4.1.3 Residual stress is superimposed on the applied stress 5.1.4 Unusually high loads or number of cycles required for
andresultsinanactualcrack-tipstressintensitythatisdifferent precracking relative to the same or similar alloy/products.
from that based solely on externally applied forces or displace- 5.1.5 A significant change in fracture toughness that is
ments. greater than that typically observed upon changing specimen
4.1.4 Teststhatutilizedeepedge-notchedspecimenssuchas configuration (for example, from C(T) to three point bend bar)
thecompacttensionC(T)areparticularlysensitivetodistortion or upon changing specimen plan size that cannot be explained
during specimen machining when influential residual stress is by other means. For example, if residual stress is biasing
present.Ingeneral,forthosecaseswheresuchresidualstresses fracture toughness tests results, then increasing the specimen
are thermal quench induced, the resulting K or K result is plan size typically results in increasing K values.
Ic q q
typically biased upward (that is, K is higher than that which
q
NOTE 1—Otherfactors,suchasasteeplyrisingR-curve(PracticeE561)
would have been achieved in a residual stress free specimen).
in high toughness alloy/products, may also be responsible for K values
q
The inflated values result from the combination of specimen
increasing with increasing specimen plan size.
distortionandbendingmomentscausedbytheredistributionof
5.1.6 A nonlinear load-COD trace during the initial elastic
residual stress during specimen machining and excessive
portion of the test record. This result is indicative of the
fatigue precrack from curvature .
residual stress clamping that is being overcome to open the
4.2 This guide can serve the following purposes:
crack under the progressively increasing applied load.
4.2.1 Provide warning signs that the measured value of K
Ic
has been biased by residual stresses and may not be a lower
6. Minimizing Effects of Residual Stress on Fracture
limit value of fracture toughness.
Toughness Measurements
4.2.2 Provide experimental methods by which to minimize
6.1 When testing aluminum products that have not been
the effect of residual stress on measured fracture toughness
stress relieved, there are two approaches available to minimize
values.
or eliminate the effects of residual stress on fracture toughness
4.2.3 Suggest methods that can be used to correct residual
measurements. The first approach involves the use of one or
stress influenced values of fracture toughness to values that
more experimental methods designed to minimize the residual
approximate a fracture toughness value representative of a test
stress in test specimens. The second approach involves the use
performed without residual stress bias.
of post-test correction methods to estimate the fracture tough-
ness K or K that would have been obtained had the test
q Ic
5. Warning Signs
specimen been free of residual stress.
5.1 There are a number of warning signs that test measure-
ments are or might be biased by the presence of residual stress.
7. Experimental Methods to Minimize Effects of Residual
If any one or more of the following conditions exist, residual
Stress
stress bias of the ensuing plane strain fracture toughness test
7.1 The following considerations can be used to minimize
resultshouldbe
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.