1.1 本规程提供了结构声发射（AE）监测指南，如压力容器、管道系统或其他可通过机械或热方式施加应力的结构。 1.2 声发射监测系统的基本功能是检测、定位和分类发射源。其他无损检测（NDT）方法可用于进一步评估所报告声发射源的重要性。 1.3 单位- 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值不一定是精确的等价物；因此，为确保符合本标准，每个系统应独立使用，且两个系统的值不得组合。 1.4 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。 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 受控刺激，即施加机械或热负荷，可以从结构的缺陷区域产生声发射。来源可能包括裂纹扩展、氧化物断裂、裂纹面粘附和负载释放以及裂纹面摩擦。 5.2 高于正常使用（峰值）载荷的载荷范围用于在裂纹尖端之前的塑性应变区域中扩展疲劳裂纹。 裂纹扩展可能不是声发射的可靠来源，这取决于合金和微观结构、裂纹扩展量（速率）以及裂纹扩展段中脆性断裂的可能性。 5.3 导致显著延性撕裂的载荷增加可能会产生比预期的裂纹扩展量更少的发射。导致更脆解理断裂的过程更容易检测到，并产生更多的发射，从而产生更少的裂纹增长。这些包括裂纹扩展的腐蚀疲劳和应力腐蚀开裂模式，并且铸造或焊接结构中比制造（锻造、轧制或挤压）结构中更可能出现这种情况。高温钢中的分布缺陷结构，如氢脆或蠕变空化，也可能在没有现有裂纹迹象的情况下产生显著的发射- 就像瑕疵一样。 5.4 施加和松弛载荷会产生与裂纹扩展无关的二次机械诱导发射。这包括加载时裂纹面粘滞释放，通常通过在相同的上升载荷值下的发射来证明，而不管峰值载荷如何；或当断裂面重新结合时，裂纹面摩擦载荷释放。 5.5 负荷率可能是一个重要问题，因为仪器可能会因AE活动而饱和。区分真实数据和背景噪声的能力可能会受到影响。 5.6 在开始任何声发射监测之前，必须充分调查并最小化背景噪声。

1.1 This practice provides guidelines for acoustic emission (AE) monitoring of structures, such as pressure vessels, piping systems, or other structures that can be stressed by mechanical or thermal means. 1.2 The basic functions of an AE monitoring system are to detect, locate, and classify emission sources. Other methods of nondestructive testing (NDT) may be used to further evaluate the significance of reported acoustic emission sources. 1.3 Units— The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 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 Controlled stimulation, that is, the application of mechanical or thermal load, can generate AE from flawed areas of the structure. Sources may include flaw growth, oxide fracture, crack face stiction and release on load application, and crack face rubbing. 5.2 The load range above normal service (peak) load is used to propagate fatigue cracks in the plastically strained region ahead of the crack tip. Crack propagation may not be a reliable source of AE, depending on the alloy and microstructure, the amount (rate) of crack extension, and possibility of brittle fracture in a segment of crack extension. 5.3 Load increases resulting in significant ductile tearing may produce less emission than expected for the amount of crack growth. Processes that result in more brittle cleavage fractures are more detectable and produce more emission for smaller amounts of flaw growth. These include corrosion fatigue and stress corrosion cracking modes of flaw growth, and would also be more likely in cast or welded structures than in fabricated (forged, rolled, or extruded) structures. Distributed defect structures such as hydrogen embrittlement, or creep cavitation in high temperature steels, may also produce significant emission without evidence of an existing crack-like flaw. 5.4 Application and relaxation of load can produce secondary mechanically-induced emission that is not related to flaw extension. This includes crack face stiction release on loading—usually evidenced by emission at the same rising load value regardless of peak load; or crack face rubbing on load release as the fracture surfaces come back together. 5.5 The load rate can be a significant concern as instrumentation can become saturated with AE activity. The ability to differentiate real data from background noise can be compromised. 5.6 Background noise must be fully investigated and minimized before any AE monitoring can begin.