1.1 本实践确立了使用称为飞行时间衍射(TOFD)的超声波技术开发超声波检查程序的要求。 1.2 根据ASTM政策，TOFD可被视为一种超声波测试方法，通过该方法评估、测量并在某些情况下识别被测试项目的质量和特性。测量可能受到精度和偏差的影响，所述精度和偏差可以统计地或作为一些参数(诸如波长)的函数来确定。该实践可用于定量检查以及定量测试的应用。 1.3 以SI单位或英寸-磅单位表示的值应单独视为标准值。每个系统中陈述的值不一定完全等同；因此，为确保符合标准，每个系统应独立使用，两个系统的数值不得合并使用。 1.4 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 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》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 4.1 本实践提供了应用飞行时间衍射技术作为检测和确定不连续性尺寸的工具的一般原则。 4.2 TOFD是一种不基于振幅响应的无损超声检测技术。然而，需要足够的敏感性来确定评估的适应症。 4.3 TOFD技术通常应用于碳钢焊接接头，但其原理可适用于其他应用，包括具有缔约方同意的合适验证程序的其他材料。 4.4 除了独立的超声波检测技术之外，TOFD可以与焊接检查结合使用，例如实践中描述的那些 E164 和 E1961 其中它可用于改进由手动或机械化脉冲检测到的缺陷的尺寸估计-回波技术，并有助于区分缺陷和几何反射器。 4.5 该技术已被证明对厚度从9毫米到300毫米【0.375英寸。到12英寸。】.TOFD已用于此范围之外的厚度，但需要特殊考虑。应证明在该厚度范围之外开发的技术能够满足所用质量标准的检测和尺寸要求。

1.1 This practice establishes the requirements for developing ultrasonic examination procedures using the ultrasonic technique known as Time-of-Flight Diffraction (TOFD). 1.2 Consistent with ASTM Policy, TOFD may be regarded as an ultrasonic test method whereby the qualities and characteristics of the item tested are evaluated, measured, and, in some cases, identified. Measurements may be subject to precision and bias that may be determined statistically or as a function of some parameter(s) such as wavelength. This practice may be used for applications that would be quantitative examinations as well as quantitative tests. 1.3 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 ====== 4.1 This practice provides general principles for the application of the Time-of-Flight Diffraction technique as a tool for detection and sizing of discontinuities. 4.2 TOFD is a nondestructive ultrasonic examination technique that is not based on amplitude response. However, sufficient sensitivity is required to identify indications for evaluation. 4.3 TOFD techniques are typically applied to welded joints in carbon steel, but the principles may be applicable to other applications including other materials with suitable validation procedures agreeable to the contracting parties. 4.4 In addition to a stand-alone ultrasonic detection technique, TOFD may be used in conjunction with weld examinations such as those described in Practices E164 and E1961 where it may be used to improve sizing estimates of flaws detected by the manual or mechanized pulse-echo techniques and help discriminate between flaws and geometric reflectors. 4.5 The technique has proven effective on thicknesses from 9 mm to 300 mm [0.375 in. to 12 in.]. TOFD has been used on thicknesses outside of this range but special considerations are necessary. Techniques developed outside of this range of thickness shall be demonstrated as capable of meeting the required detection and sizing requirements of the specification used.