Studies on Characteristics of Friction Stir Welded Joints in Structural Thin Aluminium Alloys Part 1: Imperfections in Friction Stir Welded Zones and Their Precision Non-Destructive Testing

Abstract

By applying ultrasonic phased array testing selected as precision non-destructive testing to friction stir welded zones of 5083-O, 6N01-T5 and 7N01-T5 alloys with 3 mm thickness for parent materials, the detectability of imperfections in their zones was studied in comparison with both actual imperfections and current non-destructive testing. Significant noise resulting from the surface flash on the joint was indicated as band-like signals and in order to inspect accurately, the removal before testing or the testing from both sides was proposed. A small and thin planar cavity localized and included inside the stirred zones and also a small lack of penetration could be detected, which seemed to be almost impossible to detect by current testing. Further study was considered to be required, towards the practical use, such as identification of size and shape of imperfections and effect of angle incident upon imperfections on signals intensity.