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This document specifies methods for determining fracture toughness in terms of K, δ, J and R-curves for homogeneous metallic materials subjected to quasistatic loading. Specimens are notched, precracked by fatigue and tested under slowly increasing displacement. The fracture toughness is determined for individual specimens at or after the onset of ductile crack extension or at the onset of ductile crack instability or unstable crack extension. In cases where cracks grow in a stable manner under ductile tearing conditions, a resistance curve describing fracture toughness as a function of crack extension is measured. In some cases in the testing of ferritic materials, unstable crack extension can occur by cleavage or ductile crack initiation and growth, interrupted by cleavage extension. The fracture toughness at crack arrest is not covered by this document. Special testing requirements and analysis procedures are necessary when testing weldments, and these are described in ISO 15653 which is complementary to this document. Statistical variability of the results strongly depends on the fracture type, for instance, fracture toughness associated with cleavage fracture in ferritic steels can show large variation. For applications that require high reliability, a statistical approach can be used to quantify the variability in fracture toughness in the ductile-to-brittle transition region, such as that given in ASTM E1921. However, it is not the purpose of this document to specify the number of tests to be carried out nor how the results of the tests are to be applied or interpreted.

This document specifies a method for tensile testing of test pieces of foil and strip of metals with a nominal thickness less than 0,200 mm by using computer-controlled testing machines. The used test pieces according to this document are rectangular (parallel sided strips) and are prepared by cutting. This method is used to determine typically the proof strength, Rp0,2, the tensile strength, Rm, the percentage plastic extension at fracture, Ax mm, (using the automatic determination by the machine) or the (plastic) elongation after fracture, Ax mm, (by manual determination). NOTE 1 The use of a computer-controlled tensile testing machine is important to apply parameters and fulfil several procedures. NOTE 2 EN ISO 6892 1:2019 Annex B specifies test pieces (shape, dimensions, preparation, determination of the original cross-sectional area) for thin products flats between 0,1 mm and 3 mm thickness. EN ISO 6892 1:2019 Clause B.1 specifies requirements for products of less than 0,5 mm thickness, which can require special precautions. NOTE 3 This document and EN ISO 6892 1:2019 Annex B both apply to products of thickness between 0,1 mm and 0,2 mm. For further information, see Clause 5.