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Title: Application of electromagnetic acoustic transducers to coarse-grained material

Abstract

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.

Authors:
 [1]
  1. Magnasonics, Inc., Albuquerque, NM (United States)
Publication Date:
Research Org.:
Electric Power Research Inst., Palo Alto, CA (United States); Magnasonics, Inc., Albuquerque, NM (United States)
Sponsoring Org.:
EPRI; Electric Power Research Inst., Palo Alto, CA (United States)
OSTI Identifier:
5640464
Report Number(s):
EPRI-NP-7438
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
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-)

Citation Formats

Alers, G A. Application of electromagnetic acoustic transducers to coarse-grained material. United States: N. p., 1991. Web.
Alers, G A. Application of electromagnetic acoustic transducers to coarse-grained material. United States.
Alers, G A. 1991. "Application of electromagnetic acoustic transducers to coarse-grained material". United States.
@article{osti_5640464,
title = {Application of electromagnetic acoustic transducers to coarse-grained material},
author = {Alers, G A},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/5640464}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jul 01 00:00:00 EDT 1991},
month = {Mon Jul 01 00:00:00 EDT 1991}
}

Technical Report:
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