Значение и использование
Reference blocks fabricated to this practice will exhibit specific area-amplitude and distance-amplitude relationships only with an immersion test at 5 MHz using the search unit, test instrument, and test parameters described in this practice. Comparison tests at other frequencies or with uncalibrated test systems will not necessarily give the same relationships shown in this practice.
Note 2—The 1964 and prior issues of this practice required a test frequency of 15 MHz. Blocks conforming to earlier issues of this practice may not produce ultrasonic responses that conform to this issue. See Section 13 regarding provision for recertification or correction curves and tables.
Although the primary ultrasonic evaluation of blocks is performed at a specified frequency, the blocks may be used to standardize ultrasonic tests at any frequency and with any pulse-echo ultrasonic test system. Establishment of distance-amplitude and area-amplitude characteristics is necessary for each application. This use may be inappropriate for other materials and curved surfaces without special compensation. Also see (3) for cautions regarding use of standard blocks for test standardization.
1.1 This practice covers a procedure for fabricatingaluminum alloy ultrasonic standard reference blocks that can beused for checking performance of ultrasonic testing equipment andfor standardization and control of ultrasonic tests of aluminumalloy products using pulsed longitudinal waves introduced into testmaterial either by the direct-contact method or by the immersionmethod. A recommended procedure for checking blocks is describedand calibration data for a number of reference blocks aretabulated. Statements concerning procedures are provided without adiscussion of the technical background for the preference. Thenecessary technical background can be found in Refs. (1-16).
Note 1—Practice E 428and Guide E 1158 also describe procedures for selecting material,fabricating blocks, and checking response. Unlike this practice,there is no requirement for evaluation relative to a specifiedstandard target.
1.2 This standard does notpurport to address all of the safety concerns, if any, associatedwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices and determinethe applicability of regulatory limitations prior touse.