Title: Innovative concept and application of EC probe for inspection of friction stir welds

Authors: P. Vilaça; T.G. Santos; L. Rosado; R.M. Miranda

Addresses: Department of Engineering Design and Production, School of Engineering, Aalto University, P.O. Box 14200, FI – 00076 Aalto, Finland ' Faculdade de Ciências e Tecnologia – UNL, Departamento de Engenharia Mecânica e Industrial, Quinta da Torre, Caparica 2829-516, Portugal ' INESC, Instituto de Telecomunicações, Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisbon 1049-001, Portugal ' Faculdade de Ciências e Tecnologia – UNL, Departamento de Engenharia Mecânica e Industrial, Quinta da Torre, Caparica 2829-516, Portugal

Abstract: This paper addresses a new non-destructive testing (NDT) system composed by a planar eddy currents (EC) probe (ionic probe), electronic devices for signal generation, conditioning and conversion, automated mechanised scanning, and analysis software. The ionic probe allows a 3D-induced current in the material and an easy interpretation of the signal based on a comprehensible perturbation of the signal. This provides enhanced lift-off immunity and improved sensitivity. The ionic system was developed focussing micro-defects detection on aluminium alloys processed by FSW. The experimental results in AA2024 welded by FSW clearly show that this system is able to detect imperfections around 50 µm, which contribute to increasing the reliability on NDT of micro-imperfections. EC conventional probes are also applied as material characterisation technique. Results are compared to micro-structural analysis, and hardness measurements show that EC can map the different zones, providing a deeper understanding on precipitate dispersion and grain shape and size.

Keywords: ionic probe; eddy current probes; NDT; nondestructive testing; friction stir welding; microdefects; defect detection; aluminium alloys; weld inspection; ionic probes; microstructure; hardness measurements; precipitate dispersion; grain shape; grain size.

DOI: 10.1504/IJMMP.2014.066912

International Journal of Microstructure and Materials Properties, 2014 Vol.9 No.3/4/5, pp.314 - 326

Published online: 16 Jan 2015 *

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