Standard Test Method for Ultrasonic Surface Examinations Using Electromagnetic Acoustic Transducer (EMAT) Techniques

SCOPE
1.1 This test method covers guidelines for utilizing EMAT techniques for detecting material discontinuities that are primarily open to the surface (for example, cracks, seams, laps, cold shuts, laminations, through leaks, lack of fusion). This technique can be sensitive to flaws and discontinuities that are not surface-breaking, provided their proximity to the surface is less than or equal to the Rayleigh wave length.
1.2 This test method covers procedures for the non-contact coupling of surface waves into a material via electromagnetic fields.
1.3 The procedures of this test method are applicable to any material in which acoustic waves can be introduced electromagnetically. This includes any material that is either electrically conductive or ferromagnetic, or both.
1.4 This test method is intended to provide examination capabilities for in-process, final, and maintenance applications.
1.5 This test method does not provide standards for the evaluation of derived indications. Interpretation, classification, and ultimate evaluation of indications, albeit necessary, are beyond the scope of this document. Separate specifications or agreement will be necessary to define the type, size, location, and direction of indications considered acceptable or non-acceptable.
1.6 The values stated in inch-pound units are to be regarded as the standards. The SI units given in parentheses are for information only.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
09-Jul-1998
Technical Committee
Drafting Committee
Current Stage
Ref Project

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ASTM E1962-98 - Standard Test Method for Ultrasonic Surface Examinations Using Electromagnetic Acoustic Transducer (EMAT) Techniques
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E 1962 – 98
Standard Test Method for
Ultrasonic Surface Examinations Using Electromagnetic
1
Acoustic Transducer (EMAT) Techniques
This standard is issued under the fixed designation E 1962; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 587 Practice for Ultrasonic Angle-Beam Examination by
2
the Contact Method
1.1 This test method covers guidelines for utilizing EMAT
2
E 1316 Terminology for Nondestructive Examinations
techniques for detecting material discontinuities that are pri-
E 1774 Guide to Electromagnetic Acoustic Transducers
marily open to the surface (for example, cracks, seams, laps,
2
(EMATs)
cold shuts, laminations, through leaks, lack of fusion). This
E 1816 Practice for Ultrasonic Examinations Using Electro-
technique can also be sensitive to flaws and discontinuities that
2
magnetic Acoustic Transducer (EMAT) Techniques
are not surface-breaking, provided their proximity to the
2.2 ANSI/ASNT Standards:
surface is less than or equal to the Rayleigh wave length.
Recommended Practice SNT-TC-1A Personnel Qualifica-
1.2 This test method covers procedures for the non-contact
3
tion and Certification in Nondestructive Testing
coupling of surface waves into a material via electromagnetic
ANSI/ASNT CP-189 Standard for Qualification and Certi-
fields.
3
fication of Nondestructive Testing Personnel
1.3 The procedures of this test method are applicable to any
2.3 Military Standard:
material in which acoustic waves can be introduced electro-
MIL-STD-410 Nondestructive Testing Personnel Qualifica-
magnetically. This includes any material that is either electri-
4
tion and Certification
cally conductive or ferromagnetic, or both.
1.4 This test method is intended to provide examination
3. Terminology
capabilities for in-process, final, and maintenance applications.
3.1 Definitions:
1.5 This test method does not provide standards for the
3.1.1 Additional related terminology is defined in Terminol-
evaluation of derived indications. Interpretation, classification,
ogy E 1316.
and ultimate evaluation of indications, albeit necessary, are
3.2 Definitions of Terms Specific to This Standard:
beyond the scope of this document. Separate specifications or
3.2.1 electromagnetic acoustic transducer (EMAT)—an
agreement will be necessary to define the type, size, location,
electromagnetic device for converting electrical energy into
and direction of indications considered acceptable or non-
acoustical energy in the presence of a magnetic field.
acceptable.
3.2.2 Lorentz forces—applied to electric currents when
1.6 The values stated in inch-pound units are to be regarded
placed in a magnetic field. Lorentz forces are perpendicular to
as the standards. The SI units given in parentheses are for
both the direction of the magnetic field and the current
information only.
direction. Lorentz forces are the forces responsible behind the
1.7 This standard does not purport to address all of the
principle of electric motors.
safety concerns, if any, associated with its use. It is the
3.2.3 magnetostrictive forces—forces arising from magnetic
responsibility of the user of this standard to establish appro-
domain wall movements within a magnetic material during
priate safety and health practices and determine the applica-
magnetization.
bility of regulatory limitations prior to use.
3.2.4 meander coil—an EMAT coil consisting of periodic,
2. Referenced Documents winding, non-intersecting, and usually evenly-spaced conduc-
tors.
2.1 ASTM Standards:
2
Annual Book of ASTM Standards, Vol 03.03.
1 3
This test method is under the jurisdiction of ASTM Committee E-7 on Available from American National Standards Institute, 11 W. 42nd St. 13th
Nondestructive Testing and is the direct responsibility of Subcommittee E07.06 on Floor, New York, NY 10036.
4
Ultrasonic Method. Available from the Superintendent of Documents, U.S. Government Printing
Current edition approved July 10, 1998. Published December 1998. Office, Washington, DC 20402.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

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E 1962
4. Summary of Test Method
4.1 The techniques outlined in this test method address the
electromagnetic generation of Rayleigh acoustic wave modes
for sensitivity to surface or near-surface flaws or discontinui-
ties. Flaws are detected by reflection or attenuation of acoustic
FIG. 2 Typical EMAT Meander Coil for Generation of Surface
waves from interactions at discontinuity interfaces. Waves
4.2 Fig. 1 shows one typical
...

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