ASTM-E2472 Standard Test Method for Determination of Resistance to Stable Crack Extension under Low-Constraint Conditions

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Standard Test Method for Determination of Resistance to Stable Crack Extension under Low-Constraint Conditions




1.1 This standard covers the determination of the resistance to stable crack extension in metallic materials in terms of the critical crack-tip-opening angle (CTOA), ψc and/or the crack-opening displacement (COD), δ5 resistance curve (1).2 This method applies specifically to fatigue pre-cracked specimens that exhibit low constraint (crack-size-to-thickness and un-cracked ligament-to-thickness ratios greater than or equal to 4) and that are tested under slowly increasing remote applied displacement. The test specimens are the compact, C(T), and middle-crack-tension, M(T), specimens. The fracture resistance determined in accordance with this standard is measured as ψc (critical CTOA value) and/or δ 5 (critical COD resistance curve) as a function of crack extension. Both fracture resistance parameters are characterized using either a single-specimen or multiple-specimen procedures. These fracture quantities are determined under the opening mode (Mode I) of loading. Influences of environment and rapid loading rates are not covered in this standard, but the user must be aware of the effects that the loading rate and laboratory environment may have on the fracture behavior of the material.

1.2 Materials that are evaluated by this standard are not limited by strength, thickness, or toughness, if the crack-size-to-thickness (a/B) ratio and the ligament-to-thickness (b/B) ratio are greater than or equal to 4, which ensures relatively low and similar global crack-front constraint for both the C(T) and M(T) specimens (2, 3).

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.


crack-opening displacement (COD); crack-tip-opening angle, CTOA; crack-tip-opening displacement, CTOD; critical CTOA (ψc);  δ5 resistance curve; ductile fracture; elastic-plastic fracture; fracture instability; low-constraint specimens; stable crack extension; 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

2012(E1) EDITION



Modification Type

Editorially changed

Publication Date

March 1, 2013

Document Type

Test Method

Page Count

26 pages

Committee Number