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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.

VTT Symposium. IAEA Specialist's Meeting on Inspection of Austenitic Dissimilar Materials and Welds
Valtion Teknillinen Tutkimuskeskus (Symposium) <91, 1988, Espoo>
Conference Paper
Fraunhofer IZFP ()
dissimilar metal weld; EMUS-probe; far probe surface; near probe surface; SH-wave; surface inspection; testing from austenitic side; testing from ferritic side

Ultrasonic testing of dissimilar metal welds is complicated by the coarse anisotropic grain structure of the weld metal and the mismatch of the acoustical impedance at the interface base metal/weld metal, which results in enhanced scattering, sound beam deviation and distortion, reflection and refraction of the incidend sound field at the interface base metal/weld metal. It is known that the propagation of SV-waves is much more influenced by the structure of the weld metal than the propagation of SH-waves. The paper will present 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 permanentmagnets. Especially results of investigations concerning the testing of dissimilar metal welds in a nuclear power plant of advanced technology will be reported. These diss imilar metal welds can not 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. (IZFP)