Analysis of Eddy Current Testing Detection Ability to the Varied Longitudinal Cracks on Coated Weld Metal Tee Joint of 5083 Aluminum Ship Structure

Abstract

Due to its service, crack sometimes occur on the coated 5083 aluminum weld metal. One method for finding crack under protective coating is by using eddy current testing (ECT). This method of nondestructive testing relies on a circular electrical path generated by the coils positioned just above the surface being examined. The purpose of this research is to analyze the sensitivity of ECT by using variety of crack dimensions on 5083 aluminum welded plate tee joint. Five test pieces, each 200 mm × 50 mm × 10 mm were used and each sample contain four cracks. Artificial cracks are fabricated using electrical discharge machining (EDM) with length and depth variations. Variations in crack length are 5.0 mm, 7.0 mm, 9.0 mm, and 15.0 mm, and variation in depth are 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm and 2.5 mm. Results obtained by the analysing height and average length of the crack signal indication are as follows: for 0.5 mm crack depth, the height of the crack signal is 5 mm; 1.0 mm depth is 11.75 mm; 1.5 mm depth is 19.75 mm; 2.0 mm depth is 26.5 mm and 2.5 mm depth is 31.25 mm. The degree of accuracy obtained for the detection of crack depth is 93.57%. For the detection of crack length, it is found that the measured average length of artificial cracks is 5 mm actual crack length has measured crack length of 6.32 mm; 7 mm actual crack length has measured crack length value of 7.18 mm; 9 mm actual crack length has a measured crack length value of 8.8 mm and 15 mm actual crack length has measured crack length of 14.48 mm. The degree of accuracy obtained for crack length detection is 91.31%.