Determining the Minimum Allowable Size of an Artificial Reflector in Ultrasonic Testing of Welded Joints of Aluminum High-Voltage Equipment Housings Used in Railway Transport

Objective: the development of a modern regulatory framework for ultrasonic testing (UT) of welded joints of high-voltage equipment housings made of aluminum alloys used in railway transport, prompted by the conceptual obsolescence of the current methodology. Methods: a critical analysis of the existing methodology according to RD 24.201.07-90 was carried out, identifying its key shortcomings, the principal one being the use of the wedge angle as the main inspection parameter instead of the beam angle commonly accepted in modern practice. The velocity of shear ultrasonic waves in AMg3 alloy was experimentally determined. Mechanical tests were performed on specimens with artificial reflectors (slits) to establish a correlation between defect sizes and echo-signal amplitude. Results: an accurate value of the shear wave velocity in AMg3 alloy, necessary for correct flaw detector calibration, was obtained. Based on the experimental data, new inspection sensitivity values and rejection levels were substantiated and proposed, which differ from those prescribed by GOST ISO 11666 and take into account the specific acoustic properties of aluminum alloys. Practical significance: the proposed solutions make it possible to update the UT methodology for welded joints of aluminum high-voltage equipment housings, ensure the reliability of defect detection in accordance with modern safety requirements in railway transport, and create a basis for developing an updated regulatory document to replace the outdated RD 24.201.07-90.