ASTM-E647 Standard Test Method for Measurement of Fatigue Crack Growth Rates

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Standard Test Method for Measurement of Fatigue Crack Growth Rates




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 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:



Referenced Documents




Summary of Use


Significance and Use




Specimen Configuration, Size, and Preparation




Calculations and Interpretation of Results




Precision and Bias


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 Crack Size

Annex A6

Recommended Data Reduction Techniques

Appendix X1

Recommended Practice for Determination of Fatigue Crack Opening Force From Compliance

Appendix X2

Guidelines for Measuring the Growth Rates Of Small Fatigue Cracks

Appendix X3

Recommended Practice for Determination Of ACR-Based Stress-Intensity Factor Range

Appendix X4

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 Specimen

Annex A3

1.10 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.


constant amplitude; crack size; fatigue crack growth rate; stress intensity factor range; ICS Number Code 77.040.10 (Mechanical testing of metals)

To find similar documents by ASTM Volume:

03.01 (Metals -- Mechanical Testing; Elevated and Low-Temperature Tests; Metallography)

To find similar documents by classification:

77.040.10 (Mechanical testing of metals Mechanical testing in general, see 19.060 Mechanical testing of welded joints, see 25.160.40)

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Document Number


Revision Level

2015(E1) EDITION



Modification Type

Editorially changed

Publication Date

Aug. 1, 2016

Document Type

Test Method

Page Count

49 pages

Committee Number