ASTM E494-95(2001)
(Practice)Standard Practice for Measuring Ultrasonic Velocity in Materials
Standard Practice for Measuring Ultrasonic Velocity in Materials
SCOPE
1.1 This practice covers a test procedure for measuring ultrasonic velocities in materials with conventional ultrasonic pulse echo flaw detection equipment in which results are displayed in an A-scan display. This practice describes a method whereby unknown ultrasonic velocities in a material sample are determined by comparative measurements using a reference material whose ultrasonic velocities are accurately known.
1.2 This procedure is intended for solid materials 5 mm (0.2 in.) thick or greater. The surfaces normal to the direction of energy propagation shall be parallel to at least ±3°. Surface finish for velocity measurements shall be 3.2 μm (125 μin.) rms or smoother.
Note 1—Sound wave velocities are cited in this practice using the fundamental units of meters per second, with inches per second supplied for reference in many cases. For some calculations, it is convenient to think of velocities in units of millimeters per microsecond. While these units work nicely in the calculations, the more natural units were chosen for use in the tables in this practice. The values can be simply converted from m/sec to mm/μsec by moving the decimal point three places to the left, that is, 3500 m/s becomes 3.5 mm/μsec.
1.3 Ultrasonic velocity measurements are useful for determining several important material properties. Young's modulus of elasticity, Poisson's ratio, acoustic impedance, and several other useful properties and coefficients can be calculated for solid materials with the ultrasonic velocities if the density is known (see Appendix X1).
1.4 More accurate results can be obtained with more specialized ultrasonic equipment, auxiliary equipment, and specialized techniques. Some of the supplemental techniques are described in Appendix X2. (Material contained in Appendix X2 is for informational purposes only.)
Note 2—Factors including techniques, equipment, types of material, and operator variables will result in variations in absolute velocity readings, sometimes by as much as 5%. Relative results with a single combination of the above factors can be expected to be much more accurate (probably within a 1% tolerance).
1.5 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.
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Designation:E494–95 (Reapproved 2001)
Standard Practice for
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Measuring Ultrasonic Velocity in Materials
This standard is issued under the fixed designation E494; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This specification has been approved for use by agencies of the Department of Defense.
combination of the above factors can be expected to be much more
1. Scope
accurate (probably within a 1% tolerance).
1.1 This practice covers a test procedure for measuring
1.5 This standard does not purport to address all of the
ultrasonic velocities in materials with conventional ultrasonic
safety concerns, if any, associated with its use. It is the
pulse echo flaw detection equipment in which results are
responsibility of the user of this standard to establish appro-
displayed in an A-scan display. This practice describes a
priate safety and health practices and determine the applica-
method whereby unknown ultrasonic velocities in a material
bility of regulatory limitations prior to use.
sample are determined by comparative measurements using a
reference material whose ultrasonic velocities are accurately
2. Referenced Documents
known.
2.1 ASTM Standards:
1.2 Thisprocedureisintendedforsolidmaterials5mm(0.2
2
C597 Test Method for Pulse Velocity Through Concrete
in.) thick or greater. The surfaces normal to the direction of
E317 Practice for Evaluating Performance Characteristics
energy propagation shall be parallel to at least 63°. Surface
of Ultrasonic Pulse-Echo Examination Instruments and
finishforvelocitymeasurementsshallbe3.2µm(125µin.)rms
Systems Without the Use of Electronic Measurement
or smoother.
3
Instruments
NOTE 1—Sound wave velocities are cited in this practice using the
E797 Practice for Measuring Thickness by Manual Ultra-
fundamental units of meters per second, with inches per second supplied
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sonic Pulse-Echo Contact Method
for reference in many cases. For some calculations, it is convenient to
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E1316 Terminology for Nondestructive Examinations
think of velocities in units of millimeters per microsecond. While these
units work nicely in the calculations, the more natural units were chosen
3. Terminology
for use in the tables in this practice. The values can be simply converted
from m/sec to mm/µsec by moving the decimal point three places to the
3.1 Definitions—For definitions of terms used in this prac-
left, that is, 3500 m/s becomes 3.5 mm/µsec.
tice, see Terminology E1316.
1.3 Ultrasonic velocity measurements are useful for deter-
4. Summary of Practice
miningseveralimportantmaterialproperties.Young’smodulus
4.1 Several possible modes of vibration can propagate in
of elasticity, Poisson’s ratio, acoustic impedance, and several
solids. This procedure is concerned with two velocities of
other useful properties and coefficients can be calculated for
propagation,namelythoseassociatedwithlongitudinal(v)and
solid materials with the ultrasonic velocities if the density is
l
transverse (v) waves. The longitudinal velocity is independent
known (see Appendix X1).
t
of sample geometry when the dimensions at right angles to the
1.4 More accurate results can be obtained with more spe-
beamareverylargecomparedwithbeamareaandwavelength.
cialized ultrasonic equipment, auxiliary equipment, and spe-
Thetransversevelocityislittleaffectedbyphysicaldimensions
cialized techniques. Some of the supplemental techniques are
ofthesample.TheproceduredescribedinSection6is,asnoted
described in Appendix X2. (Material contained in Appendix
in the scope, for use with conventional pulse echo flaw
X2 is for informational purposes only.)
detection equipment only.
NOTE 2—Factors including techniques, equipment, types of material,
and operator variables will result in variations in absolute velocity
5. Apparatus
readings, sometimes by as much as 5%. Relative results with a single
5.1 The ultrasonic testing system to be used in this practice
shall include the following:
5.1.1 Test Instrument—Any ultrasonic instrument compris-
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This practice is under the jurisdiction of ASTM Committee E07 on Nonde- ing a time base, transmitter (pulser), receiver (echo amplifier),
structive Testing and is the direct responsibility of Subcommittee E07.06 on
Ultrasonic Method.
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Current edition approved January 15, 1995. Published March 1995. Originally Annual Book of ASTM Standards, Vol 04.02.
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published as E494–73. Last previous edition E494–92a. Annual Book of ASTM Standards, Vol 03.03.
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