Institut de soudure has worked in two directions for transverse defects detection. The first state of the work has been to define the best ultrasonic configuration for two thicknesses (20 mm and 60mm). For that, two specific reference blocks with flat bottom holes were provided. Welds with intentional defects were also available.
Two configurations have been defined (figure 1). For 20 mm thick weld, we usetwo 60° shear wave probes in transmissionmode in a symmetrical V configuration.The open angle is 60°. For 60 mm thick weld, we use also two 45° shear wave probes in transmission mode but in a asymmetrical V configuration. The open angle is 90°.
 Figure 1: configuration for transverse defect detection |
At the same time, a small hand scanner has been developed. The chosen design allows a quick change between the two configurations. Magnets maintain contact between probes and steel plates. Position is stored via an optical encoder by a new software developed by Institut de Soudure. A specific algorithm has been developed to position the defect in the weld.
Multi-run weld surface defect detection with conventional magnetic technique is affected by many parameters like back ground noise du to variations of magnetic properties. We must also inspect in two perpendicular directions.
To avoid these problems, IXTREM has been developing a new sensor with isotrope response. Harmonic analysis allows to discriminate between defect signal and lift-off effect. Others processings applied on phase or magnetic image (construct by scanning the sensor) will give new possibilities of analysis.
Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00
Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:
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