1.1 本规程涵盖了用于慢应变率（SSR）试验的轴向加载拉伸试样和疲劳预裂纹（断裂力学）试样的设计、制备和使用程序，以研究金属材料对环境辅助裂纹（EAC）的阻力。虽然一些研究人员将SSR测试技术与循环或疲劳载荷相结合，但尚未尝试将此类技术纳入本实践中。 1.2 慢应变速率测试适用于在测试环境中评估各种金属材料，这些测试环境模拟水、非水和气体环境，在很大的温度和压力范围内，可能导致敏感材料的EAC。 1.3 本规程的主要用途是提供可接受的程序，用于在各种环境条件下加速测试金属材料对EAC的电阻。在许多情况下，通过在试样的标准截面或缺口尖端或裂纹尖端或两者中应用动态应变，加速了EAC的启动。由于该试验的加速性质，结果不一定代表使用性能，而是为筛选、检测与材料的环境相互作用以及比较评估冶金和环境变量对已知环境开裂问题敏感性的影响提供基础。 1.4 有关SSR测试方法的更多信息，请参阅ISO 7539和本规程提供的参考文献 ( 1- 6. ) . 2. 1.5 以国际单位制表示的数值应视为标准值。国际单位制后括号中给出的值仅供参考，不被视为标准值。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户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。 此外，在某些情况下，如果在SSR测试中使用高压或有毒化学环境，或两者都使用，则需要特殊设施将这些测试与实验室人员隔离。 1.7 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 慢应变率测试用于相对快速地筛选或比较评估环境、加工或冶金变量，或两者兼有，这可能会影响材料对EAC的电阻。例如，该测试技术已用于评估材料、热处理、环境中的化学成分以及温度和化学抑制剂。 5.2 在可能的情况下，SSR测试的应用和从其使用中获得的数据应与服务经验或长期EAC数据或两者结合使用，通过文献来源或使用其他测试技术的附加测试获得。在之前很少或没有SSR测试经验或很少有关于特定材料/环境组合的EAC数据的应用中，建议采取以下步骤: 5.2.1 SSR测试应在应用扩展率的范围内进行（即，应用扩展率在10%以上和10%以下通常至少一个数量级） −6. 在中/s（2.54×10 –5 确定应力或应力强度因子的应变率或增长率对EAC敏感性的影响。 5.2.2 恒定负载或应变EAC测试也应在模拟服务环境中进行，并应获得服务经验，以便在SSR测试结果和预期服务性能之间建立相关性。 5.3 在许多情况下，SSR测试被发现是EAC的保守测试。因此，在不一定导致EAC在役应用的条件下，它可能会在实验室中产生故障。此外，在某些有限的情况下，即使在观察到服务故障的情况下，在平滑张力SSR测试中也没有发现EAC指示。这种影响通常发生在局部腐蚀过程延迟开始时。因此，中给出的建议 5.2 强烈鼓励。 5.4 在某些情况下，EAC只会在特定的应变率范围内发生。因此，如果事先信息很少，则应在中讨论的应变率范围内进行测试 5.2 .

1.1 This practice covers procedures for the design, preparation, and use of axially loaded, tension test specimens and fatigue pre-cracked (fracture mechanics) specimens for use in slow strain rate (SSR) tests to investigate the resistance of metallic materials to environmentally assisted cracking (EAC). While some investigators utilize SSR test techniques in combination with cyclic or fatigue loading, no attempt has been made to incorporate such techniques into this practice. 1.2 Slow strain rate testing is applicable to the evaluation of a wide variety of metallic materials in test environments which simulate aqueous, nonaqueous, and gaseous service environments over a wide range of temperatures and pressures that may cause EAC of susceptible materials. 1.3 The primary use of this practice is to furnish accepted procedures for the accelerated testing of the resistance of metallic materials to EAC under various environmental conditions. In many cases, the initiation of EAC is accelerated through the application of a dynamic strain in the gauge section or at a notch tip or crack tip, or both, of a specimen. Due to the accelerated nature of this test, the results are not intended to necessarily represent service performance, but rather to provide a basis for screening, for detection of an environmental interaction with a material, and for comparative evaluation of the effects of metallurgical and environmental variables on sensitivity to known environmental cracking problems. 1.4 Further information on SSR test methods is available in ISO 7539 and in the references provided with this practice ( 1- 6 ) . 2 1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.6 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. Furthermore, in some cases, special facilities will be required to isolate these tests from laboratory personnel if high pressures or toxic chemical environments, or both, are utilized in SSR testing. 1.7 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 slow strain rate test is used for relatively rapid screening or comparative evaluation, or both, of environmental, processing or metallurgical variables, or both, that can affect the resistance of a material to EAC. For example, this testing technique has been used to evaluate materials, heat treatments, chemical constituents in the environment, and temperature and chemical inhibitors. 5.2 Where possible, the application of the SSR test and data derived from its use should be used in combination with service experience or long-term EAC data, or both, obtained through literature sources or additional testing using other testing techniques. In applications where there has been little or no prior experience with SSR testing or little EAC data on the particular material/environment combination of interest, the following steps are recommended: 5.2.1 The SSR tests should be conducted over a range of applied extension rates (that is, usually at least one order of magnitude in applied extension rate above and below 10 −6 in./s (2.54 × 10 –5 mm/s) to determine the effect of strain rate or rate of increase of the stress or stress intensity factor on susceptibility to EAC. 5.2.2 Constant load or strain EAC tests should also be conducted in simulated service environments, and service experience should be obtained so that a correlation between SSR test results and anticipated service performance can be developed. 5.3 In many cases the SSR test has been found to be a conservative test for EAC. Therefore, it may produce failures in the laboratory under conditions which do not necessarily cause EAC under service application. Additionally, in some limited cases, EAC indications are not found in smooth tension SSR tests even when service failures have been observed. This effect usually occurs when there is a delay in the initiation of localized corrosion processes. Therefore, the suggestions given in 5.2 are strongly encouraged. 5.4 In some cases, EAC will only occur in a specific range of strain rates. Therefore, where there is little prior information available, tests should be conducted over a range of strain rates as discussed in 5.2 .