ASTM-E587:15(R2020) pdf free download – Standard Practice for UItrasonic Angle-Beam Contact Testing.
7. Standardization
7.1 If quantitative information is to be obtained, vertical or horizontal linearity or both should be checked in accordance with Practice E317 or another procedure approved by the examining agency and the customer. An acceptable linearity performance may be agreed upon between the examining agency and the customer.
7.2 Prior to examination, standardize the system in accordance with the product specification.
7.2. 1 Angle—Beam Longitudinal and Shear Yvives.
7.2.1 .1 Distance Standardization—To locate reflectors accurately within the production item, a baseline standardization is recommended, either in terms of the component’s dimensions or the beam path. Reflections from concentric cylindrical surfaces, such as provided by some 11W blocks and the AWS distance retérence block, may be used to adjust sweep range and delay. However, if the part has suitable geometry, the part provides a more reliable standardization. Where the inspection zone includes the full volume between parallel surfaces, it is recommended that at least one Vee path he established on the screen when examining in one direction or at least one-half Vee path when examining (from surface to surface) in two direct ions.
7.2. 1 .2 A inplitude’ Standardization—Amplitude standardi zaLion (gain) is generally established on one or more reference reflectors such as side-drilled holes parallel to the major surfaces of the article being inspected and perpendicular to the sound path, flat-bottom holes drilled at the testing angle and equal radius reflectors. Surface notches can also accomplish this end under some circumstances. The reflector indication can be used to adjust the gain control in the desired level for detecting the minimum size reflector. For quantitative evaluation, distance amplitude correction may he performed electronically, by drawing a distance amplitude correction (DAC) curve on the screen, or by the use of charts and curves showing the relationship of amplitude and distance for a particular search unit and material. Unless otherwise stated, the gain should be adjusted to provide an 80 % of full screen (as long as it is within the linearity limit) maximum indication from the reference reflector.
7.2.1.3 Often the same reference reflector can be used for both distance and ampliwde standardization. An example for low-attenuation material using a single side-drilled hole at a depth of T/4 is shown in Fig. 16.
Adjust range to place indication 9 at sweep division 9. Since these controls interact. repeat the delay and range adjustments until indications I and 9 are placed at sweep divisions I and 9. Adjust gain to provide an 80 % of full-screen indication from the highest of the 1, 3, 5, 7, or 9 indications. At this gain, mark the maximum amplitudes on the screen from the reflector at 1, 3. 5, 7, and 9. Connect these points for the distance amplitude correction (DAC) curve or compensate electronically if equivalency can be demonstrated. Corner reflections from the hole to the surface may be observed at about 4 and 8 divisions on the sweep. These indications will not be used in the distance amplitude correction (DAC) curve. Measure position of the reflector on the surface from the front of the search unit (or the beam centerline projection on the side of the wedge) to the surface projection of the hole. Since the depth to the hole is known, the standardization provides means for estimating the position, dcpth. and relative response of an unknown reflector.