ASTM E2491-13(2018)

Standard Guide for Evaluating Performance Characteristics of Phased-Array Ultrasonic Testing Instruments and Systems

SIGNIFICANCE AND USE
5.1 This guide is intended to evaluate performance assessment of combinations of phased-array probes and instruments. It is not intended to define performance and acceptance criteria, but rather to provide data from which such criteria may be established.  
5.2 Recommended procedures described in this guide are intended to provide performance-related measurements that can be reproduced under the specified test conditions using simple targets and the phased-array test system itself. It is intended for phased-array flaw detection instruments operating in the nominal frequency range of 1 MHz to 20 MHz, but the procedures are applicable to measurements on instruments utilizing significantly higher frequency components.  
5.3 This guide is not intended for service calibration, or maintenance of circuitry for which the manufacturer’s instructions are available.  
5.4 Implementation of specific assessments may require more detailed procedural instructions in a format of the using facility.  
5.5 The measurement data obtained may be employed by users of this guide to specify, describe, or provide a performance criteria for procurement and quality assurance, or service evaluation of the operating characteristics of phased-array systems.  
5.6 Not all assessments described in this guide are applicable to all systems. All or portions of the guide may be used as determined by the user.
SCOPE
1.1 This guide describes procedures for evaluating some performance characteristics of phased-array ultrasonic examination instruments and systems.  
1.2 Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with this guide are expressed in terms that relate to their potential usefulness for ultrasonic examinations. Other electronic instrument characteristics in phased-array units are similar to non-phased-array units and may be measured as described in Practice E1065 or Guide E1324.  
1.3 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated.  
1.4 This guide establishes no performance limits for examination systems; if such acceptance criteria are required, these must be specified by the using parties. Where acceptance criteria are implied herein they are for example only and are subject to more or less restrictive limits imposed by customer’s and end user’s controlling documents.  
1.5 The specific parameters to be evaluated, conditions and frequency of test, and report data required, must also be determined by the user.  
1.6 This guide may be used for the evaluation of a complete examination system, including search unit, instrument, interconnections, scanner fixtures and connected alarm and auxiliary devices, primarily in cases where such a system is used repetitively without change or substitution. This guide is not intended to be used as a substitute for calibration or standardization of an instrument or system to inspect any given material.  
1.7 Required test apparatus includes selected test blocks and position encoders in addition to the instrument or system to be evaluated.  
1.8 Precautions relating to the applicability of the procedures and interpretation of the results are included.  
1.9 Alternate procedures, such as examples described in this document, or others, may only be used with customer approval.  
1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.11 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 app...

General Information

• Status: Historical
• Publication Date: 31-Oct-2018
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.06 - Ultrasonic Method

Standards Content (Sample)

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: E2491 − 13 (Reapproved 2018)
Standard Guide for
Evaluating Performance Characteristics of Phased-Array
Ultrasonic Testing Instruments and Systems
This standard is issued under the fixed designation E2491; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 Required test apparatus includes selected test blocks and
position encoders in addition to the instrument or system to be
1.1 This guide describes procedures for evaluating some
evaluated.
performance characteristics of phased-array ultrasonic exami-
1.8 Precautions relating to the applicability of the proce-
nation instruments and systems.
dures and interpretation of the results are included.
1.2 Evaluation of these characteristics is intended to be used
1.9 Alternate procedures, such as examples described in this
for comparing instruments and systems or, by periodic
document, or others, may only be used with customer approval.
repetition, for detecting long-term changes in the characteris-
tics of a given instrument or system that may be indicative of
1.10 The values stated in SI units are to be regarded as
impending failure, and which, if beyond certain limits, will
standard. No other units of measurement are included in this
require corrective maintenance. Instrument characteristics
standard.
measured in accordance with this guide are expressed in terms
1.11 This standard does not purport to address all of the
that relate to their potential usefulness for ultrasonic examina-
safety concerns, if any, associated with its use. It is the
tions. Other electronic instrument characteristics in phased-
responsibility of the user of this standard to establish appro-
array units are similar to non-phased-array units and may be
priate safety, health, and environmental practices and deter-
measured as described in Practice E1065 or Guide E1324.
mine the applicability of regulatory limitations prior to use.
1.12 This international standard was developed in accor-
1.3 Ultrasonic examination systems using pulsed-wave
trains and A-scan presentation (rf or video) may be evaluated. dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
1.4 This guide establishes no performance limits for exami-
Development of International Standards, Guides and Recom-
nation systems; if such acceptance criteria are required, these
mendations issued by the World Trade Organization Technical
must be specified by the using parties. Where acceptance
Barriers to Trade (TBT) Committee.
criteria are implied herein they are for example only and are
subject to more or less restrictive limits imposed by customer’s
2. Referenced Documents
and end user’s controlling documents. 2
2.1 ASTM Standards:
1.5 The specific parameters to be evaluated, conditions and
E317 Practice for Evaluating Performance Characteristics of
frequency of test, and report data required, must also be
Ultrasonic Pulse-Echo Testing Instruments and Systems
determined by the user.
without the Use of Electronic Measurement Instruments
E494 Practice for Measuring Ultrasonic Velocity in Materi-
1.6 This guide may be used for the evaluation of a complete
als
examination system, including search unit, instrument,
E1065 Practice for Evaluating Characteristics of Ultrasonic
interconnections, scanner fixtures and connected alarm and
Search Units
auxiliary devices, primarily in cases where such a system is
E1316 Terminology for Nondestructive Examinations
used repetitively without change or substitution. This guide is
E1324 Guide for Measuring Some Electronic Characteristics
not intended to be used as a substitute for calibration or
of Ultrasonic Testing Instruments
standardization of an instrument or system to inspect any given
material.
3. Terminology
3.1 Refer to Terminology E1316 for definitions of terms in
this guide.
This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-
tive Testing and is the direct responsibility of Subcommittee E07.06 on Ultrasonic
Method. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2018. Published December 2018. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2013 as E2491 – 13. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2491-13R18. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2491 − 13 (2018)
4. Summary of Guide when the hole diameter is between about 1.5 mm and 2.5 mm
and 20 mm to 25 mm in length.
4.1 Phased-array instruments and systems have similar in-
dividual components as are found in traditional ultrasonic
5. Significance and Use
systems that are based on single channel or multiplexed
5.1 This guide is intended to evaluate performance assess-
pulse-echo units. These include pulsers, receivers, probes, and
ment of combinations of phased-array probes and instruments.
interconnecting cables. The most significant difference is that
It is not intended to define performance and acceptance criteria,
phased-array systems form the transmitted ultrasonic pulse by
but rather to provide data from which such criteria may be
constructive phase interference from the wavelets formed off
established.
the individually pulsed elements of the phased-array probes.
5.2 Recommended procedures described in this guide are
4.2 Each phased-array probe consists of a series of individu-
intended to provide performance-related measurements that
ally wired elements that are activated separately using a
can be reproduced under the specified test conditions using
programmable time delay pattern. Varying the number of
simple targets and the phased-array test system itself. It is
elements used and the delay time between the pulses to each
intended for phased-array flaw detection instruments operating
element allows control of the beam. Depending on the probe
in the nominal frequency range of 1 MHz to 20 MHz, but the
design, it is possible to electronically vary the angle (incident
procedures are applicable to measurements on instruments
or skew), or the focal distance, or the beam dimensions, or a
utilizing significantly higher frequency components.
combination of the three. In the receiving mode, acoustic
5.3 This guide is not intended for service calibration, or
energy is received by the elements and the signals undergo a
maintenance of circuitry for which the manufacturer’s instruc-
summation process utilizing the same type of time delay
tions are available.
process as was used during transmission.
5.4 Implementation of specific assessments may require
4.3 The degree of beam steering available is dependent on
more detailed procedural instructions in a format of the using
several parameters including; number of elements, pitch of the
facility.
element spacing, element dimensions, element array shape,
5.5 The measurement data obtained may be employed by
resonant frequency of the elements, the material into which the
users of this guide to specify, describe, or provide a perfor-
beam is directed, the minimum delay possible between firing of
mance criteria for procurement and quality assurance, or
adjacent pulsers and receivers and the pulser voltage charac-
service evaluation of the operating characteristics of phased-
teristics.
array systems.
4.4 Pulser and receiver parameters in phased-array systems
5.6 Not all assessments described in this guide are appli-
are generally computer controlled and the received signals are
cable to all systems. All or portions of the guide may be used
typically displayed on computer monitors via computer data
as determined by the user.
acquisition systems and may be stored to computer files.
6. Procedure
4.5 Although most systems use piezo-electric materials for
the elements, electro-magnetic acoustic transducer (EMAT) 6.1 Procedures for assessment of several parameters in
devices have also been designed and built using phased-array
phased-array systems are described in Annex A1 – Annex A7.
instrumentation. 6.1.1 These include; determination of beam profile, beam
steering capability, element activity, focusing capability, soft-
4.6 Most phased array systems can use encoders for auto-
ware calculations (controls and display of received signals),
mated and semi-automated scanning.
compensation for wedge attenuation, receiver gain linearity.
4.7 Side Drilled Holes used as targets in this document
7. Keywords
should have diameters less than the wavelength of the pulse
being assessed and long enough to avoid end effects from
7.1 characterization; focal point; phased-array; phased-array
causing interfering signals. This will typically be accomplished probe; sound beam profile; ultrasound
E2491 − 13 (2018)
ANNEXES
(Mandatory Information)
A1. DETERMINATION OF PHASED-ARRAY BEAM PROFILE
A1.1 Introduction electronic scan sequence for probes with sufficient number of
elements to electronically advance the beam past the targets of
A1.1.1 This annex describes procedures to determine beam
interest. For phased array probes using a large portion of the
profiles of phased-array probes. Either immersion or contact
available elements to form the beam the number of remaining
probe applications can be addressed using these procedures.
elements for the electronic raster may be too small to allow the
However, it should be cautioned that assessments of contact
beam to pass over the target. In this case it will be necessary to
probes may suffer from variability greater than imposed
have encoded mechanical motion and assess each focal law
tolerances if proper precautions are not taken to ensure
constant coupling conditions. along the active plane separately.
A1.2.3 Side-drilled holes should be arranged at various
A1.2 Test Setup
depths in a flaw-free sample of the test material in which focal
A1.2.1 For single focal laws where the beam is fixed (that
laws have been programmed for. Using the linear scan feature
is, not used in an electronic or sectorial scan mode) and the
of the phased-array system the beam is passed over the targets
probe is used in an immersion setup, the ball-target or
at the various depths of interest. The electronic scan is
hydrophone options described in Practice E1065 may be used.
illustrated schematically in Fig. A1.1.
For phased array probes used in a dynamic fashion where
several focal laws are used to produce sectorial or electronic
A1.2.4 Data collection of the entire waveform over the
scanning it may be possible to make beam-profile assessments
range of interest shall be made. The display shall represent
with no or little mechanical motion. Where mechanical motion
amplitude as a color or grayscale. Time or equivalent distance
is used it shall be encoded to relate signal time and amplitude
in the test material shall be presented along one axis and
to distance moved. Encoder accuracy shall be verified to be
distance displaced along the other axis. This is a typical B-scan
within tolerances appropriate for the measurements made.
as illustrated in Fig. A1.2.
Descriptions made for electronic scan and sectorial scan beam
profile assessments will be made for contact probes; however,
A1.2.5 Data display for an electronic scan using a phased-
when assessment in water is required the machined targets may array probe mounted on a wedge can be similarly made using
be replaced with rods or balls as appropriate.
simple orthogonal representation of time versus displacement
or it can be angle corrected as illustrated in Fig. A1.3.
A1.2.2 Linear-Array Probes—Linear-array probes have an
active plane and an inactive or passive plane. Assessment of
the beam in the active plane should be made by use of an
FIG. A1.1 Electronic Scan of Side Drilled Holes
E2491 − 13 (2018)
FIG. A1.2 B-Scan Display of Electronic Scan Represented in Fig. A1.1 (Depth is in the vertical axis and electronic-scan distance is rep-
resented along the horizontal axis.)
FIG. A1.3 Angle-Corrected B-Scan of a Phased-Array Beam (in Shear Wave Mode) from a Side Drilled Hole (Off-axis lobe effects can be
seen in the display.)
A1.2.6 Resolution along the displacement axis will be a chanical motion in the passive plane provides data that can be
function of the step size of the electronic scan or, if the scan
projection-corrected to provide beam dimensions in the passive
uses an encoded mechanical fixture the resolution will be
plane. Fig. A1.4 illustrates a method for beam assessment in
dependent on the encoder step-size used for sampling.
the passive plane. This technique uses a corner reflection from
an end-drilled hole at depths established by a series of steps.
A1.2.7 Resolution along the beam axis will be a function of
the intervals between the target paths. For highly focused
A1.2.10 Fig. A1.5 illustrates an alternative to the stepped
beams it may be desirable to have small differences between
intervals shown in Fig. A1.4. A through hole may be arranged
the sound paths to the target paths (for example, 1 mm or
perpendicular to the required refracted angle to provide a
2 mm).
continuous transition of path length to the target.
A1.2.8 Beam profiling in the passive plane can also be
A1.2.11 A projected C-scan can be used to size the beam
made. The passive plane in a linear-array probe is perpendicu-
based on either color or grayscale indicating amplitude drop or
lar to the active plane and refers to the plane in which no beam
a computer display that plots amplitude with respect to
steering is possible by phasing effects. Beam profiling in the
displacement. The projected C-scan option is schematically
passive direction will require mechanical scanning.
represented in Fig. A1.6.
A1.2.9 Waveform collection of signals using a combination
of electronic scanning in the active plane and encoded me-
E2491 − 13 (2018)
FIG. A1.4 Scanning End-Drilled Holes to Obtain Beam Dimensions in Passive Plane
FIG. A1.5 Representation of an Inclined Hole for Beam Characterization in the Passive Plane
FIG. A1.6 Representation of Projected C-Scan of Corner Effect Scan Seen in Fig. A1.4
A2. DETERMINATION OF PHASED-ARRAY BEAM STEERING LIMITS
A2.1 Introduction A2.1.2 Recommended limits to establish the working range
of angular sweep of a phased-ar
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2491 − 13 E2491 − 13 (Reapproved 2018)
Standard Guide for
Evaluating Performance Characteristics of Phased-Array
Ultrasonic Testing Instruments and Systems
This standard is issued under the fixed designation E2491; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*Scope
1.1 This guide describes procedures for evaluating some performance characteristics of phased-array ultrasonic examination
instruments and systems.
1.2 Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition,
for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure,
and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with
this guide are expressed in terms that relate to their potential usefulness for ultrasonic examinations. Other electronic instrument
characteristics in phased-array units are similar to non-phased-array units and may be measured as described in GuidePractice
E1065 or Guide E1324.
1.3 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated.
1.4 This guide establishes no performance limits for examination systems; if such acceptance criteria are required, these must
be specified by the using parties. Where acceptance criteria are implied herein they are for example only and are subject to more
or less restrictive limits imposed by customer’s and end user’s controlling documents.
1.5 The specific parameters to be evaluated, conditions and frequency of test, and report data required, must also be determined
by the user.
1.6 This guide may be used for the evaluation of a complete examination system, including search unit, instrument,
interconnections, scanner fixtures and connected alarm and auxiliary devices, primarily in cases where such a system is used
repetitively without change or substitution. This guide is not intended to be used as a substitute for calibration or standardization
of an instrument or system to inspect any given material.
1.7 Required test apparatus includes selected test blocks and position encoders in addition to the instrument or system to be
evaluated.
1.8 Precautions relating to the applicability of the procedures and interpretation of the results are included.
1.9 Alternate procedures, such as examples described in this document, or others, may only be used with customer approval.
1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.11 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.12 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.
2. Referenced Documents
2.1 ASTM Standards:
This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.06 on Ultrasonic Method.
Current edition approved June 1, 2013Nov. 1, 2018. Published June 2013December 2018. Originally approved in 2006. Last previous edition approved in 20082013 as
E2491 - 08.E2491 – 13. DOI: 10.1520/E2491-13.10.1520/E2491-13R18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2491 − 13 (2018)
E317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-Echo Testing Instruments and Systems without the
Use of Electronic Measurement Instruments
E494 Practice for Measuring Ultrasonic Velocity in Materials
E1065 Practice for Evaluating Characteristics of Ultrasonic Search Units
E1316 Terminology for Nondestructive Examinations
E1324 Guide for Measuring Some Electronic Characteristics of Ultrasonic Testing Instruments
3. Terminology
3.1 Refer to Terminology E1316 for definitions of terms in this guide.
4. Summary of Guide
4.1 Phased-array instruments and systems have similar individual components as are found in traditional ultrasonic systems that
are based on single channel or multiplexed pulse-echo units. These include pulsers, receivers, probes, and interconnecting cables.
The most significant difference is that phased-array systems form the transmitted ultrasonic pulse by constructive phase
interference from the wavelets formed off the individually pulsed elements of the phased-array probes.
4.2 Each phased-array probe consists of a series of individually wired elements that are activated separately using a
programmable time delay pattern. Varying the number of elements used and the delay time between the pulses to each element
allows control of the beam. Depending on the probe design, it is possible to electronically vary the angle (incident or skew), or
the focal distance, or the beam dimensions, or a combination of the three. In the receiving mode, acoustic energy is received by
the elements and the signals undergo a summation process utilizing the same type of time delay process as was used during
transmission.
4.3 The degree of beam steering available is dependent on several parameters including; number of elements, pitch of the
element spacing, element dimensions, element array shape, resonant frequency of the elements, the material into which the beam
is directed, the minimum delay possible between firing of adjacent pulsers and receivers and the pulser voltage characteristics.
4.4 Pulser and receiver parameters in phased-array systems are generally computer controlled and the received signals are
typically displayed on computer monitors via computer data acquisition systems and may be stored to computer files.
4.5 Although most systems use piezo-electric materials for the elements, electro-magnetic acoustic transducer (EMAT) devices
have also been designed and built using phased-array instrumentation.
4.6 Most phased array systems can use encoders for automated and semi-automated scanning.
4.7 Side Drilled Holes used as targets in this document should have diameters less than the wavelength of the pulse being
assessed and long enough to avoid end effects from causing interfering signals. This will typically be accomplished when the hole
diameter is between about 1.5 mm and 2.5 mm and 20 mm to 25 mm in length.
5. Significance and Use
5.1 This guide is intended to evaluate performance assessment of combinations of phased-array probes and instruments. It is
not intended to define performance and acceptance criteria, but rather to provide data from which such criteria may be established.
5.2 Recommended procedures described in this guide are intended to provide performance-related measurements that can be
reproduced under the specified test conditions using simple targets and the phased-array test system itself. It is intended for
phased-array flaw detection instruments operating in the nominal frequency range of 1 MHz to 20 MHz, but the procedures are
applicable to measurements on instruments utilizing significantly higher frequency components.
5.3 This guide is not intended for service calibration, or maintenance of circuitry for which the manufacturer’s instructions are
available.
5.4 Implementation of specific assessments may require more detailed procedural instructions in a format of the using facility.
5.5 The measurement data obtained may be employed by users of this guide to specify, describe, or provide a performance
criteria for procurement and quality assurance, or service evaluation of the operating characteristics of phased-array systems.
5.6 Not all assessments described in this guide are applicable to all systems. All or portions of the guide may be used as
determined by the user.
6. Procedure
6.1 Procedures for assessment of several parameters in phased-array systems are described in Annex A1 – Annex A7Annexes
A1 to A7.
6.1.1 These include; determination of beam profile, beam steering capability, element activity, focusing capability, software
calculations (controls and display of received signals), compensation for wedge attenuation, receiver gain linearity.
E2491 − 13 (2018)
7. Keywords
7.1 characterization; focal point; phased-array; phased-array probe; sound beam profile; ultrasound
ANNEXES
(Mandatory Information)
A1. DETERMINATION OF PHASED-ARRAY BEAM PROFILE
A1.1 Introduction
A1.1.1 This annex describes procedures to determine beam profiles of phased-array probes. Either immersion or contact probe
applications can be addressed using these procedures. However, it should be cautioned that assessments of contact probes may
suffer from variability greater than imposed tolerances if proper precautions are not taken to ensure constant coupling conditions.
A1.2 Test Setup
A1.2.1 For single focal laws where the beam is fixed (that is, not used in an electronic or sectorial scan mode) and the probe is
used in an immersion setup, the ball-target or hydrophone options described in Practice E1065 may be used. For phased array
probes used in a dynamic fashion where several focal laws are used to produce sectorial or electronic scanning it may be possible
to make beam-profile assessments with no or little mechanical motion. Where mechanical motion is used it shall be encoded to
relate signal time and amplitude to distance moved. Encoder accuracy shall be verified to be within tolerances appropriate for the
measurements made. Descriptions made for electronic scan and sectorial scan beam profile assessments will be made for contact
probes; however, when assessment in water is required the machined targets may be replaced with rods or balls as appropriate.
A1.2.2 Linear-Array Probes—Linear-array probes have an active plane and an inactive or passive plane. Assessment of the beam
in the active plane should be made by use of an electronic scan sequence for probes with sufficient number of elements to
electronically advance the beam past the targets of interest. For phased array probes using a large portion of the available elements
to form the beam the number of remaining elements for the electronic raster may be too small to allow the beam to pass over the
target. In this case it will be necessary to have encoded mechanical motion and assess each focal law along the active plane
separately.
A1.2.3 Side-drilled holes should be arranged at various depths in a flaw-free sample of the test material in which focal laws have
been programmed for. Using the linear scan feature of the phased-array system the beam is passed over the targets at the various
depths of interest. The electronic scan is illustrated schematically in Fig. A1.1.
A1.2.4 Data collection of the entire waveform over the range of interest shall be made. The display shall represent amplitude as
a color or grayscale. Time or equivalent distance in the test material shall be presented along one axis and distance displaced along
the other axis. This is a typical B-scan as illustrated in Fig. A1.2.
A1.2.5 Data display for an electronic scan using a phased-array probe mounted on a wedge can be similarly made using simple
orthogonal representation of time versus displacement or it can be angle corrected as illustrated in Fig. A1.3.
A1.2.6 Resolution along the displacement axis will be a function of the step size of the electronic scan or, if the scan uses an
encoded mechanical fixture the resolution will be dependent on the encoder step-size used for sampling.
A1.2.7 Resolution along the beam axis will be a function of the intervals between the target paths. For highly focused beams it
may be desirable to have small differences between the sound paths to the target paths (for example, 1 mm or 2 mm).1 mm or
2 mm).
E2491 − 13 (2018)
FIG. A1.1 Electronic Scan of Side Drilled Holes
FIG. A1.2 B-Scan Display of Electronic Scan Represented in Fig. A1.1 (Depth is in the vertical axis and electronic-scan distance is rep-
resented along the horizontal axis.)
A1.2.8 Beam profiling in the passive plane can also be made. The passive plane in a linear-array probe is perpendicular to the
active plane and refers to the plane in which no beam steering is possible by phasing effects. Beam profiling in the passive direction
will require mechanical scanning.
A1.2.9 Waveform collection of signals using a combination of electronic scanning in the active plane and encoded mechanical
motion in the passive plane provides data that can be projection-corrected to provide beam dimensions in the passive plane. Fig.
A1.4 illustrates a method for beam assessment in the passive plane. This technique uses a corner reflection from an end-drilled hole
at depths established by a series of steps.
A1.2.10 Fig. A1.5 illustrates an alternative to the stepped intervals shown in Fig. A1.4. A through hole may be arranged
perpendicular to the required refracted angle to provide a continuous transition of path length to the target.
A1.2.11 A projected C-scan can be used to size the beam based on either color or grayscale indicating amplitude drop or a
E2491 − 13 (2018)
FIG. A1.3 Angle-Corrected B-Scan of a Phased-Array Beam (in Shear Wave Mode) from a Side Drilled Hole (Off-axis lobe effects can be
seen in the display.)
FIG. A1.4 Scanning End-Drilled Holes to Obtain Beam Dimensions in Passive Plane
FIG. A1.5 Representation of an Inclined Hole for Beam Characterization in the Passive Pl
...