Application of electromagnetic acoustic transducers to coarse-grained material

Technical Report · Mon Jul 01 00:00:00 EDT 1991

OSTI ID:5640464

Alers, G A ^[1]

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1. Magnasonics, Inc., Albuquerque, NM (United States)

Electromagnetic Acoustic Transducers (EMATs) have certain advantages over piezoelectric transducers because they do not require a coupling medium between the part and the transducer and they can be designed to generate and detect focused sound waves of types unavailable to conventional probes. This program investigated a 500 kHz EMAT designed to focus Shear Horizontal ultrasonic waves onto the interior of centrifugally cast stainless steel (CCSS) in the hope that the large attenuation caused by scattering from the large grains could be minimized and reflections from small defects could be more easily detected. The results demonstrated that synthetic aperture focusing had to be used to distinguish flaw echoes from backscattered noise'' but that flaw detection by a pulse-echo technique was still difficult because of the attenuation of the signal as it propagated to and from the focal point. The ability to control the angle of injection of the sound beam by simply changing the frequency was demonstrated. 4 refs., 10 figs.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (United States); Magnasonics, Inc., Albuquerque, NM (United States)
• Sponsoring Organization: EPRI; Electric Power Research Inst., Palo Alto, CA (United States)
• OSTI ID: 5640464
• Report Number(s): EPRI-NP-7438
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
47 OTHER INSTRUMENTATION
STAINLESS STEELS
ELECTROMAGNETIC TESTING
TRANSDUCERS
DESIGN
ALUMINIUM
ATTENUATION
CASTING
GRAIN SIZE
INSPECTION
MATERIALS TESTING
MINIMIZATION
NONDESTRUCTIVE TESTING
SCATTERING
ULTRASONIC WAVES
ALLOYS
CRYSTAL STRUCTURE
ELEMENTS
FABRICATION
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
METALS
MICROSTRUCTURE
SIZE
SOUND WAVES
STEELS
TESTING
420500* - Engineering- Materials Testing
440800 - Miscellaneous Instrumentation- (1990-)
426000 - Engineering- Components
Electron Devices & Circuits- (1990-)