5.1 This practice for plane-strain fracture toughness testing of aluminum alloys may be used as a supplement to Test Method E399. The application of this practice is primarily intended for quality assurance and material release in cases where valid plane-strain fracture toughness data cannot be obtained per Test Method E399.

5.2 It must be understood that the interpretations and guidelines in this practice do not alter the validity requirements of Test Method E399 or promote the designation of data that are invalid according to Test Method E399 to a “valid” condition. This practice is primarily concerned with cases where it is not possible or practical to obtain valid data, but where material release judgments must be made against specified fracture toughness values. Where it is possible to obtain a valid plane-strain fracture toughness value by replacement testing according to Test Method E399, that is the preferred approach.

1.1 This practice is applicable to the fracture toughness testing of all aluminum alloys, tempers, and products, especially in cases where the tests are being made to establish whether or not individual lots meet the requirements of specifications and should be released to customers.

1.2 Test Method E399 is the basic test method to be used for plane-strain fracture toughness testing of aluminum alloys. The purpose of this practice is to provide supplementary information for plane-strain fracture toughness of aluminum alloys in three main areas:

1.2.1 Specimen sampling,

1.2.2 Specimen size selection, and

1.2.3 Interpretation of invalid test results.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3.1 Exception—Certain inch-pound values given in parentheses are provided for information only.

1.4 This standard is currently written to accommodate only C(T) specimens.

1.5 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 and health practices and determine the applicability of regulatory limitations prior to use.