金属材料. 测定准静态断裂韧性的统一试验方法

[中文适用范围]： 本文件规定了根据受准静态载荷的均质金属材料的 K、δ、J 和 R 曲线确定断裂韧性的方法。 样品被刻痕、疲劳预裂，并在缓慢增加的位移下进行测试。 在延性裂纹扩展开始时或之后或在延性裂纹不稳定或不稳定裂纹扩展开始时测定各个样品的断裂韧性。 在裂纹在延性撕裂条件下以稳定方式生长的情况下，测量描述断裂韧性作为裂纹扩展函数的阻力曲线。 在某些情况下，在铁素体材料的测试中，解理或延性裂纹萌生和扩展可能会导致不稳定的裂纹扩展，并被解理扩展中断。 本文件未涵盖止裂断裂韧性。 测试焊件时需要特殊的测试要求和分析程序，这些在 ISO 15653 中进行了描述，该文件是对本文件的补充。 结果的统计变异性很大程度上取决于断裂类型，例如，铁素体钢中与解理断裂相关的断裂韧性可能表现出很大的变化。 对于需要高可靠性的应用，可以使用统计方法来量化延性到脆性转变区域中断裂韧性的变化，例如 ASTM E1921 中给出的方法。 然而，本文件的目的不是指定要进行的测试数量，也不是指定如何应用或解释测试结果。 [外文原描述]： 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.