1.1 This test method covers the determination of fracture toughness ( KIc ) 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 2 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 ) . 3 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: Section Referenced Documents 2 Terminology 3 Stress-Intensity Factor 3.1.1 Plane-Strain Fracture Toughness 3.1.2 Crack Plane Orientation 3.1.3 Summary of Test Method 4 Significance and Use 5 Significance 5.1 Precautions 5.1.1- 5.1.5 Practical Applications 5.2 Apparatus (see also 1.4 ) 6 Tension Machine 6.1 Fatigue Machine 6.2 Loading Fixtures 6.3 Displacement Gage, Measurement 6.4 Specimen Size, Configurations, and Preparation (see also 1.5 ) 7 Specimen Size Estimates 7.1 Standard and Alternative Specimen Configurations 7.2 Fatigue Crack Starter Notches 7.3.1 Fatigue Precracking (see also 1.6 ) 7.3.2 Crack Extension Beyond Starter Notch 7.3.2.2 General Procedure 8 Specimen Measurements Thickness 8.2.1 Width 8.2.2 Crack Size 8.2.3 Crack Plane Angle 8.2.4 Specimen Testing Loading Rate 8.3 Test Record 8.4 Calculation and Interpretation of Results 9 Test Record Analysis 9.1 Pm ax/PQ Validity Requirement 9.1.3 Specimen Size Validity Requirements 9.1.4 Reporting 10 Precision and Bias 11 1.4 Specific requirements related to test apparatus: Double-Cantilever Displacement Gage Annex A1 Testing Fixtures Annex A2 Bend Specimen Loading Fixture Annex A2.1 Compact Specimen Loading Clevis Annex A2.2 1.5 Specific requirements related to individual specimen configurations.