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现行 ISO 26843:2015
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Metallic materials — Measurement of fracture toughness at impact loading rates using precracked Charpy-type test pieces 金属材料 - 使用预包装的夏比型试件测量冲击负载率下的断裂韧性
发布日期: 2015-12-02
ISO 26843:205规定了使用断裂力学方法对金属材料进行和评估仪器化预裂纹夏比冲击试验的要求。给出了测量和记录设备的最低要求,以实现类似的灵敏度和可比测量。 当满足相应的有效性标准时,使用该国际标准确定的动态断裂力学性能与常规大规模断裂力学结果具有可比性。由于夏比试样的绝对尺寸较小,通常情况并非如此。然而,获得的数值可用于材料的研究和开发、质量控制,以及确定冲击加载速率下性能随试验温度的变化。 通过使用本国际标准确定的断裂韧性性能可能与准静态加载速率下测得的值不同。事实上,当在脆性或韧脆状态下进行试验时,加载速率的增加会导致断裂韧性的降低;在完全韧性状态下,观察到相反的情况(即断裂韧性增加)。参考文献[1]中给出了断裂韧度对加载(或应变)速率依赖性的更多信息。此外,一般认为断裂韧性也取决于试验温度。由于这些原因,用户需要报告每项测试的实际测试温度和加载速率。 如果铁素体钢在韧脆过渡区发生解理断裂,变异性可能非常大,无法用简单的统计数据充分描述。 在这种情况下,需要进行额外的试验,并使用适用于此类试验的统计程序进行分析,例如,参见参考文献[2]。 注:可能需要对参考文献[2]中规定的分析程序进行修改,以考虑较高(冲击)加载速率的影响。
ISO 26843:205 specifies requirements for performing and evaluating instrumented precracked Charpy impact tests on metallic materials using a fracture mechanics approach. Minimum requirements are given for measurement and recording equipment such that similar sensitivity and comparable measurements are achieved. Dynamic fracture mechanics properties determined using this International Standard are comparable with conventional large-scale fracture mechanics results when the corresponding validity criteria are met. Because of the small absolute size of the Charpy specimen, this is often not the case. Nevertheless, the values obtained can be used in research and development of materials, in quality control, and to establish the variation of properties with test temperature under impact loading rates. Fracture toughness properties determined through the use of this International Standard may differ from values measured at quasistatic loading rates. Indeed, an increase in loading rate causes a decrease in fracture toughness when tests are performed in the brittle or ductile-to-brittle regimes; the opposite is observed (i.e. increase in fracture toughness) in the fully ductile regime. More information on the dependence of fracture toughness on loading (or strain) rate is given in Reference [1]. In addition, it is generally acknowledged that fracture toughness also depends on test temperature. For these reasons, the user is required to report the actual test temperature and loading rate for each test performed. In case of cleavage fracture of ferritic steels in the ductile-to-brittle transition region, variability can be very large and cannot be adequately described by simple statistics. In this case, additional tests are required and the analysis is to be performed using a statistical procedure applicable to this type of test, see for example Reference [2]. NOTE Modifications to the analytical procedures prescribed in Reference [2] might be necessary to account for the effect of elevated (impact) loading rates.
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归口单位: ISO/TC 164/SC 4
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