1.1 This test method covers the determination of the plane-strain fracture toughness (KIc) of metallic materials by tests using a variety of fatigue-cracked specimens having a thickness of 0.063 in. (1.6 mm) or greater. The details of the various specimen and test configurations are shown in Annexes A1 through A7 and A9. Note 1-Plane-strain fracture toughness tests of thinner materials that are sufficiently brittle (see 7.1) can be made with other types of specimens (1). There is no standard test method for testing such thin materials. 1.2 This test method also covers the determination of the specimen strength ratio Rsx where x refers to the specific specimen configuration being tested. This strength ratio is a function of the maximum load the specimen can sustain, its initial dimensions and the yield strength of the material. 1.3 Measured values of plane-strain fracture toughness stated in inch-pound units are to be regarded as standard. 1.4 This test method is divided into two main parts. The first part gives general information concerning the recommendations and requirements for Ic testing. The second part is composed of annexes that give the displacement gage design, fatigue cracking procedures, and special requirements for the various specimen configurations covered by this method. In addition, an annex is provided for the specific procedures to be followed in rapid-load plane-strain fracture toughness tests. General information and requirements common to all specimen types are listed as follows: Sections Referenced Documents 2 Terminology 3 Stress-Intensity Factor 3.1.1 Plane-Strain Fracture Toughness 3.1.2 Summary of Test Method 4 Significance and Use 5 Precautions 5.1.1 to 5.1.3 Practical Applications 5.2 Apparatus 6 Loading Fixtures 6.2 Displacement Gage Design Annex A1 Displacement Measurements 6.3 Sections Specimens Size, Configurations, and Preparation 7 Specimen Size Estimates 7.1 Standard and Alternative Specimen Configurations 7.2 Forms of Fatigue Crack Starter Notch 7.3.1 Fatigue Cracking Annex A2 Crack Extension Beyond Starter 7.3.2.2 Measurements before Testing Thickness 8.2.1 Width 8.2.3 Starter Notch Root Radius 7.3.1 Specimen Testing Loading Rate 8.3 Test Record 8.4 Measurements after Testing Crack Length 8.2.2 Crack Plane Angle 8.2.4 Calculation and Interpretation of Results 9 Analysis of Test Record 9.1 Validity Requirements on Pmax/PQ 9.1.2 Validity Requirements on Specimen Size 9.1.3 Crack Plane Orientation Designations 9.2 Fracture Appearance Descriptions 9.3 Reporting 10 Precision and Bias 11 Special Requirements for Rapid Load K1c (t) Tests Annex A7 Bend Specimen SE(B) Annex A3 Compact Specimen C(T) Annex A4 Arc-Shaped Tension Specimen A(T) Annex A5 Disk-Shaped Compact Specimen DC(T) Annex A6 Arc-Shaped Bend Specimen Annex A9 1.5 Special requirements for the various specimen configurations appear in the following order: 1.6 This standard does not purport to address the safety problems 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.