ASTM E647-15

Standard Test Method for Measurement of Fatigue Crack Growth Rates

SIGNIFICANCE AND USE
5.1 Fatigue crack growth rate expressed as a function of crack-tip stress-intensity factor range, d a/dN versus ΔK, characterizes a material's resistance to stable crack extension under cyclic loading. Background information on the ration-ale for employing linear elastic fracture mechanics to analyze fatigue crack growth rate data is given in Refs (1)5 and (2).  
5.1.1 In innocuous (inert) environments fatigue crack growth rates are primarily a function of ΔK and force ratio, R, or Kmax and R (Note 1). Temperature and aggressive environments can significantly affect da/ dN versus ΔK, and in many cases accentuate R-effects and introduce effects of other loading variables such as cycle frequency and waveform. Attention needs to be given to the proper selection and control of these variables in research studies and in the generation of design data.
Note 1: ΔK, Kmax, and R are not independent of each other. Specification of any two of these variables is sufficient to define the loading condition. It is customary to specify one of the stress-intensity parameters (ΔK or Kmax) along with the force ratio, R.  
5.1.2 Expressing da/dN as a function of ΔK provides results that are independent of planar geometry, thus enabling exchange and comparison of data obtained from a variety of specimen configurations and loading conditions. Moreover, this feature enables d a/dN versus ΔK data to be utilized in the design and evaluation of engineering structures. The concept of similitude is assumed, which implies that cracks of differing lengths subjected to the same nominal ΔK will advance by equal increments of crack extension per cycle.  
5.1.3 Fatigue crack growth rate data are not always geometry-independent in the strict sense since thickness effects sometimes occur. However, data on the influence of thickness on fatigue crack growth rate are mixed. Fatigue crack growth rates over a wide range of ΔK have been reported to either increase, decrease, or remain unaffected as spec...
SCOPE
1.1 This test method2 covers the determination of fatigue crack growth rates from near-threshold to Kmax  controlled instability. Results are expressed in terms of the crack-tip stress-intensity factor range (ΔK), defined by the theory of linear elasticity.  
1.2 Several different test procedures are provided, the optimum test procedure being primarily dependent on the magnitude of the fatigue crack growth rate to be measured.  
1.3 Materials that can be tested by this test method are not limited by thickness or by strength so long as specimens are of sufficient thickness to preclude buckling and of sufficient planar size to remain predominantly elastic during testing.  
1.4 A range of specimen sizes with proportional planar dimensions is provided, but size is variable to be adjusted for yield strength and applied force. Specimen thickness may be varied independent of planar size.  
1.5 The details of the various specimens and test configurations are shown in Annex A1 – Annex A3. Specimen configurations other than those contained in this method may be used provided that well-established stress-intensity factor calibrations are available and that specimens are of sufficient planar size to remain predominantly elastic during testing.  
1.6 Residual stress/crack closure may significantly influence the fatigue crack growth rate data, particularly at low stress-intensity factors and low stress ratios, although such variables are not incorporated into the computation of ΔK.  
1.7 Values stated in SI units are to be regarded as the standard. Values given in parentheses are for information only.  
1.8 This test method is divided into two main parts. The first part gives general information concerning the recommendations and requirements for fatigue crack growth rate testing. The second part is composed of annexes that describe the special requirements for various specimen configurations, special requirements for testing i...

General Information

• Status: Historical
• Publication Date: 30-Apr-2015
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: E08 - Fatigue and Fracture
• Drafting Committee: E08.06 - Crack Growth Behavior

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: E647 − 15
StandardTest Method for
1
Measurement of Fatigue Crack Growth Rates
This standard is issued under the fixed designation E647; 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.
1. Scope cial requirements for testing in aqueous environments, and
2
proceduresfornon-visualcracksizedetermination.Inaddition,
1.1 This test method covers the determination of fatigue
there are appendices that cover techniques for calculating
crack growth rates from near-threshold to K controlled
max
da/dN,determiningfatiguecrackopeningforce,andguidelines
instability. Results are expressed in terms of the crack-tip
for measuring the growth of small fatigue cracks. General
stress-intensity factor range (∆K), defined by the theory of
information and requirements common to all specimen types
linear elasticity.
are listed as follows:
1.2 Several different test procedures are provided, the opti-
Section
mum test procedure being primarily dependent on the magni-
Referenced Documents 2
Terminology 3
tude of the fatigue crack growth rate to be measured.
Summary of Use 4
1.3 Materials that can be tested by this test method are not
Significance and Use 5
Apparatus 6
limited by thickness or by strength so long as specimens are of
Specimen Configuration, Size, and Preparation 7
sufficient thickness to preclude buckling and of sufficient
Procedure 8
planar size to remain predominantly elastic during testing.
Calculations and Interpretation of Results 9
Report 10
1.4 A range of specimen sizes with proportional planar
Precision and Bias 11
dimensions is provided, but size is variable to be adjusted for Special Requirements for Testing in Aqueous Environments Annex A4
Guidelines for Use of Compliance to Determine Crack Size Annex A5
yield strength and applied force. Specimen thickness may be
Guidelines for Electric Potential Difference Determination of Annex A6
varied independent of planar size.
Crack Size
Recommended Data Reduction Techniques Appendix X1
1.5 The details of the various specimens and test configu-
Recommended Practice for Determination of Fatigue Crack Appendix X2
rations are shown in Annex A1 – Annex A3. Specimen
Opening Force From Compliance
Guidelines for Measuring the Growth Rates Of Small Fatigue Appendix X3
configurations other than those contained in this method may
Cracks
be used provided that well-established stress-intensity factor
Recommended Practice for Determination Of ACR-Based Appendix X4
calibrations are available and that specimens are of sufficient
Stress-Intensity Factor Range
planar size to remain predominantly elastic during testing.
1.9 Special requirements for the various specimen configu-
rations appear in the following order:
1.6 Residualstress/crackclosuremaysignificantlyinfluence
the fatigue crack growth rate data, particularly at low stress-
The Compact Specimen Annex A1
The Middle Tension Specimen Annex A2
intensity factors and low stress ratios, although such variables
The Eccentrically-Loaded Single Edge Crack Tension Annex A3
are not incorporated into the computation of ∆K.
Specimen
1.7 Values stated in SI units are to be regarded as the
1.10 This standard does not purport to address all of the
standard.Values given in parentheses are for information only.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.8 Thistestmethodisdividedintotwomainparts.Thefirst
priate safety and health practices and determine the applica-
part gives general information concerning the recommenda-
bility of regulatory limitations prior to use.
tions and requirements for fatigue crack growth rate testing.
The second part is composed of annexes that describe the
2. Referenced Documents
special requirements for various specimen configurations, spe-
3
2.1 ASTM Standards:
E4Practices for Force Verification of Testing Machines
1
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue E6Terminology Relating to Methods of Mechanical Testing
and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack
Growth Behavior.
3
CurrenteditionapprovedMay1,2015.PublishedJuly2015.Originallyapproved For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ε1
in 1978. Last previous approved in 2013 as E647–13a . DOI: 10.1520/E0647-15. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
2
For additional information on this test method see RR: E24–1001. Available Standards volume information, refer to the standard’s Document Summary page on
fromASTM Headquarters, 100 Barr Harbor Drive,W
...

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.
´1
Designation: E647 − 13a E647 − 15
Standard Test Method for
1
Measurement of Fatigue Crack Growth Rates
This standard is issued under the fixed designation E647; 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
ε NOTE—X4.3.6 and Eq X4.3 were editorially corrected in July 2014.
1. Scope
2
1.1 This test method covers the determination of fatigue crack growth rates from near-threshold to K controlled instability.
max
Results are expressed in terms of the crack-tip stress-intensity factor range (ΔK), defined by the theory of linear elasticity.
1.2 Several different test procedures are provided, the optimum test procedure being primarily dependent on the magnitude of
the fatigue crack growth rate to be measured.
1.3 Materials that can be tested by this test method are not limited by thickness or by strength so long as specimens are of
sufficient thickness to preclude buckling and of sufficient planar size to remain predominantly elastic during testing.
1.4 A range of specimen sizes with proportional planar dimensions is provided, but size is variable to be adjusted for yield
strength and applied force. Specimen thickness may be varied independent of planar size.
1.5 The details of the various specimens and test configurations are shown in Annex A1 – Annex A3. Specimen configurations
other than those contained in this method may be used provided that well-established stress-intensity factor calibrations are
available and that specimens are of sufficient planar size to remain predominantly elastic during testing.
1.6 Residual stress/crack closure may significantly influence the fatigue crack growth rate data, particularly at low
stress-intensity factors and low stress ratios, although such variables are not incorporated into the computation of ΔK.
1.7 Values stated in SI units are to be regarded as the standard. Values given in parentheses are for information only.
1.8 This test method is divided into two main parts. The first part gives general information concerning the recommendations
and requirements for fatigue crack growth rate testing. The second part is composed of annexes that describe the special
requirements for various specimen configurations, special requirements for testing in aqueous environments, and procedures for
non-visual crack size determination. In addition, there are appendices that cover techniques for calculating da/dN, determining
fatigue crack opening force, and guidelines for measuring the growth of small fatigue cracks. General information and
requirements common to all specimen types are listed as follows:
Section
Referenced Documents 2
Terminology 3
Summary of Use 4
Significance and Use 5
Apparatus 6
Specimen Configuration, Size, and Preparation 7
Procedure 8
Calculations and Interpretation of Results 9
Report 10
Precision and Bias 11
Special Requirements for Testing in Aqueous Environments Annex A4
Guidelines for Use of Compliance to Determine Crack Size Annex A5
Guidelines for Electric Potential Difference Determination of Annex A6
Crack Size
Recommended Data Reduction Techniques Appendix X1
Recommended Practice for Determination of Fatigue Crack Appendix X2
Opening Force From Compliance
1
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack Growth
Behavior.
Current edition approved Oct. 15, 2013May 1, 2015. Published February 2014July 2015. Originally approved in 1978. Last previous approved in 2013 as
ε1
E647 – 13.E647 – 13a . DOI: 10.1520/E0647-13A.10.1520/E0647-15.
2
For additional information on this test method see RR: E24 – 1001. Available from ASTM Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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E647 − 15
Guidelines for Measuring the Growth Rates Of Small Fatigue Appendix X3
Cracks
Recommended Practice for Determination Of ACR-Based Appendix X4
Stress-Intensity Factor Range
1.9 Special requirements for the various specimen configurations appear in the following order:
The Compact Specimen Annex A1
The Middle Tension Specimen Annex A2
The Eccentrically-Loaded Single Edge Crack Tension Annex A3
Specimen
1.10 Th
...