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Title: APPLICATION OF LARGE APERTURE EMATS TO WELD INSPECTION

Abstract

One of the most significant developments in EMAT operation is the incorporation of phased array techniques. Phased array EMATs enable electronic beam steering and focusing while operating with temporally short pulses for good range resolution. Using phased array EMAT operation, multiple high powered pulsers are combined in the generation of the ultrasonic wave and multiple elements are combined in the reception of the ultrasonic wave, for improved sensitivity. EMATs make it practical to operate with shear horizontal (SH) waves and scan over a metal part's surface. An EMAT generated line force at the surface launches shear horizontal waves with uniform amplitude for beam angles from -90 deg. to 90 deg. Shear horizontal waves also reflect without mode conversion from surfaces that are parallel to the polarization of the shear wave displacements. The combination of these advantages makes phased array EMATs well suited for weld inspection. Recently, BWXT Services has developed a 32 active channel EMAT phased array system for operation up to 5 MHz. In addition, each element can be constructed with several sub-elements, alternating in polarity, to effectively multiply the number of active elements for a restricted range of beam angles. For example by using elements comprised of 4more » sub elements, a 128 active element aperture designed for operation with a nominal 60 deg. beam angle provides good beam steering and focusing performance for 45 deg. to 70 deg. beam angles. The large active apertures allow the use of highly focused beams for good defect detection and high resolution imaging of weld defects. Application of this system to weld inspections has verified that good defect detection and imaging is possible. In addition, operation with SH waves has proven to provide improved detection of lack of fusion at the cap and root of the weld for certain weld geometries. The system has also been used to demonstrate the inspection of submerged metal arc welds while welding.« less

Authors:
; ;  [1]
  1. NDE and IS Group, BWXT Services, Lynchburg, VA 24502 (United States)
Publication Date:
OSTI Identifier:
21210240
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 975; Journal Issue: 1; Conference: 34. annual review of progress in quantitative nondestructive evaluation, Golden, CO (United States), 22-27 Jul 2007; Other Information: DOI: 10.1063/1.2902747; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; APERTURES; ARC WELDING; DEFECTS; DETECTION; ELECTRON BEAMS; FOCUSING; METALS; MHZ RANGE; MODE CONVERSION; OPERATION; PERFORMANCE; PULSES; SHEAR; SURFACES; ULTRASONIC TESTING; ULTRASONIC WAVES; WELDED JOINTS

Citation Formats

Maclauchlan, D T, Clark, S P, and Hancock, J W. APPLICATION OF LARGE APERTURE EMATS TO WELD INSPECTION. United States: N. p., 2008. Web. doi:10.1063/1.2902747.
Maclauchlan, D T, Clark, S P, & Hancock, J W. APPLICATION OF LARGE APERTURE EMATS TO WELD INSPECTION. United States. https://doi.org/10.1063/1.2902747
Maclauchlan, D T, Clark, S P, and Hancock, J W. 2008. "APPLICATION OF LARGE APERTURE EMATS TO WELD INSPECTION". United States. https://doi.org/10.1063/1.2902747.
@article{osti_21210240,
title = {APPLICATION OF LARGE APERTURE EMATS TO WELD INSPECTION},
author = {Maclauchlan, D T and Clark, S P and Hancock, J W},
abstractNote = {One of the most significant developments in EMAT operation is the incorporation of phased array techniques. Phased array EMATs enable electronic beam steering and focusing while operating with temporally short pulses for good range resolution. Using phased array EMAT operation, multiple high powered pulsers are combined in the generation of the ultrasonic wave and multiple elements are combined in the reception of the ultrasonic wave, for improved sensitivity. EMATs make it practical to operate with shear horizontal (SH) waves and scan over a metal part's surface. An EMAT generated line force at the surface launches shear horizontal waves with uniform amplitude for beam angles from -90 deg. to 90 deg. Shear horizontal waves also reflect without mode conversion from surfaces that are parallel to the polarization of the shear wave displacements. The combination of these advantages makes phased array EMATs well suited for weld inspection. Recently, BWXT Services has developed a 32 active channel EMAT phased array system for operation up to 5 MHz. In addition, each element can be constructed with several sub-elements, alternating in polarity, to effectively multiply the number of active elements for a restricted range of beam angles. For example by using elements comprised of 4 sub elements, a 128 active element aperture designed for operation with a nominal 60 deg. beam angle provides good beam steering and focusing performance for 45 deg. to 70 deg. beam angles. The large active apertures allow the use of highly focused beams for good defect detection and high resolution imaging of weld defects. Application of this system to weld inspections has verified that good defect detection and imaging is possible. In addition, operation with SH waves has proven to provide improved detection of lack of fusion at the cap and root of the weld for certain weld geometries. The system has also been used to demonstrate the inspection of submerged metal arc welds while welding.},
doi = {10.1063/1.2902747},
url = {https://www.osti.gov/biblio/21210240}, journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 975,
place = {United States},
year = {Thu Feb 28 00:00:00 EST 2008},
month = {Thu Feb 28 00:00:00 EST 2008}
}