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1.1 This test method covers the determination of fracture toughness (K_Ic) of metallic materials under predominantly linear-elastic, plane-strain conditions using fatigue precracked specimens having a thickness of 1.6 mm (0.063 in.) or greater subjected to slowly, or in special (elective) cases rapidly, increasing crack-displacement force. Details of test apparatus, specimen configuration, and experimental procedure are given in the Annexes.

Note 1—Plane-strain fracture toughness tests of thinner materials that are sufficiently brittle (see 7.1) can be made using other types of specimens (1). There is no standard test method for such thin materials.

1.2 This test method is divided into two parts. The first part gives general recommendations and requirements for K_Ic testing. The second part consists of Annexes that give specific information on displacement gage and loading fixture design, special requirements for individual specimen configurations, and detailed procedures for fatigue precracking. Additional annexes are provided that give specific procedures for beryllium and rapid-force testing.

1.3 General information and requirements common to all specimen configurations:

SectionReferenced Documents2Terminology3Stress-Intensity Factor3.1.1Plane-Strain Fracture Toughness3.1.2Crack Plane Orientation3.1.3Summary of Test Method4Significance and Use5Significance5.1Precautions5.1.1-5.1.5Practical Applications5.2Apparatus (see also 1.4)6Tension Machine6.1Fatigue Machine6.2Loading Fixtures6.3Displacement Gage, Measurement6.4Specimen Size, Configurations, and Preparation (see also 1.5)7Specimen Size Estimates7.1Standard and Alternative Specimen Configurations7.2Fatigue Crack Starter Notches7.3.1Fatigue Precracking (see also 1.6)7.3.2Crack Extension Beyond Starter Notch7.3.2.2General Procedure8Specimen MeasurementsThickness8.2.1Width8.2.2Crack Size8.2.3Crack Plane Angle8.2.4Specimen TestingLoading Rate8.3Test Record8.4Calculation and Interpretation of Results9Test Record Analysis9.1P_max/P_Q Validity Requirement9.1.3Specimen Size Validity Requirements9.1.4Reporting10Precision and Bias11

1.4 Specific requirements related to test apparatus:

Double-Cantilever Displacement GageAnnex A1Testing FixturesAnnex A2Bend Specimen Loading FixtureAnnex A2.1Compact Specimen Loading ClevisAnnex A2.2

1.5 Specific requirements related to individual specimen configurations:

Bend Specimen SE(B)Annex A3Compact Specimen C(T)Annex A4Disk-Shaped Compact Specimen DC(T)Annex A5Arc-Shaped Tension Specimen A(T)Annex A6Arc-Shaped Bend Specimen A(B)Annex A7

1.6 Specific requirements related to special test procedures:

Fatigue Precracking KIc SpecimensAnnex A8Hot-Pressed Beryllium TestingAnnex A9Rapid-Force TestingAnnex A10

1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.8 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.