CONTROL OF THIN-WALLED SCREENS OF EPITAXIAL INSTALLATIONS BY THE EDDY CURRENT METHOD

Abstract

The results of testing thin-walled welded joints (high-temperature assemblies of epitaxial installations) obtained by electron-beam welding using the eddy current method are presented. The tightness of those parts and assemblies is controlled by vacuum and compression leak detection methods, based on increasing the test gas concentration on the one side of the test surface and sampling it for mass spectrometric analysis on the other side. Helium mass spectrometric leak detectors are now widely used in aerospace, electronics and chemical industries, as well as in the instrument making industry and scientific research. The eddy current method provides a high scanning speed and allows timely detection of the defects and prevention of the risk of accidental wear of thin-walled elements and parts of aerospace and petrochemical equipment. The goal of this work is to optimize the control of welded joints of thin (0.2 and 0.5 mm) tantalum screen using a VEKTOR-60D detector and eddy current method. The device provides the use of overhead or flow eddy current differential, tangential and absolute transducers operating at a frequency from 10 Hz to 20 MHz, as well as various dynamic transducers. The device is designed to control metal products, carbon plastics and composites for the presence of defects such as surface and subsurface cracks, discontinuities and homogeneity of materials. VEKTOR-60D allows one to get a simultaneous signal display on the flaw detector screen both in the amplitude-time and complex planes. The used sensors (PVDT-1000-2, PVD-200-2,3, and VP160A45) provided detection of the defects across the entire width of the weld and heat-affected zone in one pass along the welded joint. The defect of the welded joint of the tantalum screen was revealed as incomplete penetration (nonpenetration in the weld root) in accordance with the classification of GOST R ISO 6520-1–2012. The results proved that a VEKTOR-60D eddy current detector can be successfully used in monitoring defects in thin-walled welded joints.