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Inspection of dissimilar metal welds using horizontally polarized shear -SH-waves and electromagnetic ultrasonic -EMUS-probes

: Hübschen, G.; Salzburger, H.J.

International journal of pressure vessels and piping 39 (1989), pp.331-344
ISSN: 0308-0161
Journal Article
Fraunhofer IZFP ()
dissimilar metal weld; EMUS-probe; longitudinal flaw; SH-wave; surface inspection; transversal flaw

Ultrasonic testing of dissimilar metal welds is complicated by the coarse anisotropic grain structure of the weld metal and by the mismatch of the acoustic impedance at the base metallweld metal interface, which results in enhanced scattering, sound beam deviation and distortion, reflection and refraction of the incident sound field at the base metall/weld metal interface. It is known that the propagation of SV-waves is much more influenced by the structure of the weld metal than the progagation of SH-waves. This paper presents results for the surface inspection of the near probe as well as of the far probe surface of dissimilar metal welds with SH-wave EMUS-probes. Measurements were carried out from the ferritic base metal by EMUS probes with electromagnets and from the austenitic base metal by probes with permanent magnets. In particular, results of investigations concerning the testing of dissimilar metal welds in a nuclear power plant of advanced technology are reported. These diss imilar metal welds cannot be inspected with conventional ultrasonic testing methods, but with SH-waves at grazing incidence the weld can be tested from a distance of 300 mm.