ISO 12135:2016 金属材料-断裂韧度统一测定试验

标准编号：ISO 12135:2016

中文名称：金属材料-断裂韧度统一测定试验

英文名称：Metallic materials — Unified method of test for the determination of quasistatic fracture toughness

发布日期：2016-11

标准范围

ISO 12135:2016规定了根据承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。试样有缺口，经过疲劳预裂，并在缓慢增加的位移下进行试验。在韧性裂纹扩展开始时或之后，或在韧性裂纹失稳或不稳定裂纹扩展开始时，测定单个试样的断裂韧性。在铁素体材料试验的某些情况下，不稳定的裂纹扩展可通过解理或韧性裂纹萌生和扩展发生，并被解理扩展中断。本文件不包括止裂时的断裂韧性。如果裂纹在延性撕裂条件下以稳定的方式扩展，则测量描述断裂韧性作为裂纹扩展函数的阻力曲线。在大多数情况下，结果的统计可变性不大，报告三个或更多测试结果的平均值是可以接受的。在韧脆过渡区铁素体材料发生解理断裂的情况下，可变性可能很大，可能需要额外的测试来量化统计可变性。测试焊接件时，需要特殊的测试要求和分析程序，ISO 15653对这些要求和程序进行了描述，ISO 15653是对本文件的补充。当解理导致断裂或解理之前出现有限延性裂纹扩展时，根据ASTM E1921进行测试和分析，确定材料的参考温度可能有用。[2]

ISO 12135:2016 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 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. 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 most cases, statistical variability of the results is modest and reporting the average of three or more test results is acceptable. In cases of cleavage fracture of ferritic materials in the ductile-to-brittle transition region, variability can be large and additional tests may be required to quantify statistical variability. Special testing requirements and analysis procedures are necessary when testing weldments and these are described in ISO 15653 which is complementary to this document.When fracture occurs by cleavage or when cleavage is preceded by limited ductile crack extension, it may be useful to establish the reference temperature for the material by conducting testing and analysis in accordance with ASTM E1921.[2]

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