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Standard Practice for Measuring Ultrasonic Velocity in Materials by Comparative Pulse-Echo Method
Přeložit název
NORMA vydána dne 1.12.2020
Označení normy: ASTM E494-20
Datum vydání normy: 1.12.2020
Kód zboží: NS-1015314
Počet stran: 14
Přibližná hmotnost: 42 g (0.09 liber)
Země: Americká technická norma
Kategorie: Technické normy ASTM
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, and 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. The ultrasonic testing system that shall be used shall consist of the test instrument, search unit, couplant, and the standard reference blocks. The test procedure shall include both longitudinal and transverse wave velocity measurements, which should conform to the theoretical values of the parameters.
Keywords:
measure of ultrasonic velocity, nondestructive testing, ultrasonic properties of materials, ultrasonic thickness gauges, ultrasonic velocity,, ICS Number Code 77.040.20 (Non-destructive testing of metals)
Significance and Use | ||||||||||||||||
5.1?This practice describes a test procedure for the application of conventional ultrasonic methods to determine unknown ultrasonic velocities in a material sample by comparative measurements using a reference material whose ultrasonic velocities are accurately known. 5.2?Although not all methods described in this practice are applied equally or universally to all velocity measurements in different materials, it does provide flexibility and a basis for establishing contractual criteria between users, and may be used as a general guideline for preparing a detailed procedure or specification for a particular application. 5.3?This practice is directed towards the determination of longitudinal and shear wave velocities using the appropriate sound wave form. This practice also outlines methods to determine elastic modulus and can be applied in both contact and immersion mode. |
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1. 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 ?m (125 ?in.) root-mean-square (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/s to mm/?s by
moving the decimal point three places to the left, that is, 3500
m/s becomes 3.5 mm/?s.
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 than those obtained using this method 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?UnitsThe values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.6?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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. |
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2. Referenced Documents | ||||||||||||||||
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