1.1 本试验方法涵盖了通过断裂载荷试验方法评估抗应力腐蚀开裂（SCC）能力的程序，这是一个使用残余强度作为损伤演变测量（在这种情况下是环境辅助开裂）的概念。 1.2 该试验方法包括试样类型和复制、试验环境、应力水平、暴露时间、最终强度测定和原始残余强度数据的统计分析。 1.3 该试验方法适用于可热处理铝合金，即2XXX合金和7XXX合金（1.2至3.0） % Cu和相对于晶粒结构定向的短横向试样 ( 1. , 2. ) . 2. 然而，用于分析数据的残余强度测量和统计数据并非针对可热处理铝合金，可用于其他试样方向和不同类型的材料。 1.4 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 5.1 该试验方法用于高强度铝合金（2XXX和含铜7XXX），通常在3.5重量%氯化钠中通过交替浸泡进行试验。 然而，原则上，将残余强度作为损伤演化（在这种情况下是环境辅助开裂）的衡量标准的概念可以应用于任何合金和环境系统。 5.2 该试验方法用于研究合金和回火，以提高抗SCC性能。试验结果允许比较不同的材料变体，具有较高的置信度，并且比通过/失败试验的结果更精确。因此，它对于比较具有类似抗应力腐蚀开裂水平的材料特别有用。该程序可以修改为用作质量保证工具，但在其开发过程中，这并不是主要目的。 5.3 本试验方法中描述的暴露时间和条件特别适用于高强度铝合金，但统计技术应适用于具有不同暴露条件的其他合金系统。 5.4 尽管该特殊程序主要用于测试短横向应力方向上的产品，但它对其他应力方向，尤其是薄板和薄板产品中的长横向应力也很有用。 5.5 确定材料的实际可用性需要在预期使用环境中，在与最终用途相关的条件下，包括涂层和抑制剂等保护措施下，进行应力腐蚀试验，这超出了本试验方法的范围。 5.5.1 没有很好的方法将测试环境与实际服务进行比较，因为大多数服务环境对于可能经历许多不同环境的单个结构，或对于服务于不同位置的两个相同结构，都有很大的固有差异。 除非样品可以在实际使用环境中测试组件的预期寿命，否则无法确定特定材料是否适用于特定应用。因此，设计师必须根据对材料和使用环境的了解，对特定材料的适用性作出判断。为了避免服务故障，通常根据导致故意高估腐蚀损坏的最坏情况选择用于初步评估的环境。

1.1 This test method covers procedures for evaluation of stress corrosion cracking (SCC) resistance by the breaking load test method, a concept which uses residual strength as the measure of damage evolution (in this case environmentally assisted cracking). 1.2 This test method covers specimen type and replication, test environment, stress levels, exposure periods, final strength determination, and statistical analysis of the raw residual strength data. 1.3 The test method was developed for use with heat-treatable aluminum alloys, that is, 2XXX alloys and 7XXX with 1.2 to 3.0 % Cu, and test specimens oriented in the short-transverse direction relative to grain structure ( 1 , 2 ) . 2 However, the residual strength measurements and the statistics used to analyze the data are not specific to heat-treatable aluminum alloys and can be used for other specimen orientations and different types of materials. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 The test method was developed for use with high strength aluminum alloys (2XXX and Cu containing 7XXX) that are normally tested in 3.5 weight % NaCl by alternate immersion. However, the concept which uses residual strength as a measure of damage evolution (in this case environmentally assisted cracking) can, in principle, be applied to any alloy and environmental system. 5.2 This test method has been developed for research studies of alloys and tempers with improved resistance to SCC. The test results permit different material variants to be compared with a high degree of confidence and with much more precision than the results of pass/fail tests. Thus, it is particularly useful for comparing materials with similar levels of resistance to stress-corrosion cracking. The procedure could be modified for use as a quality assurance tool but this has not been a primary purpose during its development. 5.3 The exposure periods and conditions that are described in this test method apply specifically to high strength aluminum alloys, but the statistical techniques should be valid for other alloy systems with different exposure conditions. 5.4 Although this particular procedure was primarily intended for testing products in the short-transverse stressing direction, it is useful for other stressing directions, particularly the long-transverse direction in sheet and thin plate products. 5.5 Determination of the actual serviceability of a material requires stress-corrosion testing performed in the intended service environment, under conditions relating to the end use, including protective measures such as coatings and inhibitors and is outside the scope of this test method. 5.5.1 There is no good way to compare test environments to actual service because most service environments have large inherent variability with respect to a single structure that may experience many different environments or with respect to two identical structures that serve in different locations. Unless a sample can be tested in the actual service environment for the expected life of the component, no conclusive determination can be made about the suitability of a particular material for a particular application. Designers must therefore make judgments on the suitability of particular materials for applications based on knowledge of the material and of the service environment. To avoid service failures, the environment used for preliminary evaluations is often chosen based on a worst case scenario leading to intentional overestimations of corrosion damage.