1.1 断裂韧性是航空航天和加工工业中使用的许多铝合金的关键性能。断裂韧性测试通常用于供应商资格认证、质量控制和材料放行目的。本实践的目的是为行业提供统一的测试程序，指出在特定情况下使用的是哪些现行标准，并在没有标准的情况下提供指南。本规程为测试提供了指导 （a） 规定厚度小于6.35的板材和其他产品 毫米（0.250英寸）， （b） 对于有效平面而言过薄的板材、锻件和挤压件的中间厚度- 应变断裂韧性测试，但太厚，无法作为薄板处理，例如规定厚度大于或等于6.35 mm（0.250 in.）的产品但小于25至50毫米（1至2英寸），取决于韧性水平，以及 （c） 相对较厚产品的试验方法 E399 适用。 1.2 以国际单位制表示的数值应视为标准。括号中以英寸-磅为单位的数值仅供参考。 1.3 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。 1.4 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 本规程旨在制定和保持铝合金韧性评估规程的统一性，尤其是在供应商资格、质量保证和材料放行方面。 5.2 需要强调的是，这些程序的使用不会改变用特定测试方法确定的数据的有效性，但为解释测试结果（有效或无效）提供了指导，并为在目前没有标准的情况下选择合理的测试程序提供了指导。

1.1 Fracture toughness is a key property for a number of aluminum alloys utilized in aerospace and process industries. Fracture toughness testing is often required for supplier qualification, quality control, and material release purposes. The purpose of this practice is to provide uniform test procedures for the industry, pointing out which current standards are utilized in specific cases, and providing guidelines where no standards exist. This practice provides guidance for testing (a) sheet and other products having a specified thickness less than 6.35 mm (0.250 in.), (b) intermediate thicknesses of plate, forgings, and extrusions that are too thin for valid plane-strain fracture toughness testing but too thick for treatment as sheet, such as products having a specified thickness greater than or equal to 6.35 mm (0.250 in.) but less than 25 to 50 mm (1 to 2 in.), depending on toughness level, and (c) relatively thick products where Test Method E399 is applicable. 1.2 The values stated in SI units are to be regarded as the standard. The values in inch-pound units given in parenthesis are provided for information purposes only. 1.3 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. 1.4 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 This practice is provided to develop and maintain uniformity in practices for the evaluation of the toughness of aluminum alloys, particularly with regard to supplier qualification, quality assurance, and material release to specifications. 5.2 It is emphasized that the use of these procedures will not alter the validity of data determined with specific test methods, but provides guidance in the interpretation of test results (valid or invalid) and guidance in the selection of a reasonable test procedure in those instances where no standard exists today.