ASTM A745/A745M-94(2009)
(Practice)Standard Practice for Ultrasonic Examination of Austenitic Steel Forgings
Standard Practice for Ultrasonic Examination of Austenitic Steel Forgings
ABSTRACT
This test method deals with the procedures for the standard practice of performing contact, pulse-echo ultrasonic examination of austenitic steel forgings by the straight and angle beam techniques. This practice does not cover the ultrasonic examination of nonmagnetic retaining ring forgings. The instrument used for this test method shall be the electronic pulsed reflection type. Prior to examination, specimens shall be heat treated and machined to a rectangular, parallel, or concentric surface configuration, and its surface shall be free of extraneous material such as loose scale, paint, and dirt. Calibration of the apparatus shall be done by either the single-block method or distance-amplitude curve method. Choice of method to be employed shall be determined by the test metal distance involved. Quality levels for acceptance, established by the type and amount of indication present, are detailed thoroughly.
SCOPE
1.1 This practice covers the standards and procedures for the contact, pulse-echo ultrasonic examination of austenitic steel forgings by the straight or angle beam techniques, or both.
1.2 This practice shall be used whenever the inquiry, proposal, contract, order, or specification states that austenitic steel forgings are to be subject to ultrasonic examination in accordance with Practice A 745/A 745M. Ultrasonic examination of nonmagnetic retaining ring forgings should be made to Practice A 531/A 531M, not to this practice.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.4 This practice and the applicable material specifications are expressed in both inch-pound units and SI units. However, unless the order specifies the applicable “M” specification designation [SI units], the material shall be furnished to inch-pound units.
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:A745/A745M–94 (Reapproved 2009)
Standard Practice for
Ultrasonic Examination of Austenitic Steel Forgings
This standard is issued under the fixed designationA745/A745M; 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 without the Use of Electronic Measurement Instruments
E428 Practice for Fabrication and Control of Metal, Other
1.1 This practice covers the standards and procedures for
than Aluminum, Reference Blocks Used in Ultrasonic
the contact, pulse-echo ultrasonic examination of austenitic
Testing
steelforgingsbythestraightoranglebeamtechniques,orboth.
2.2 American Society for Nondestructive Testing Docu-
1.2 This practice shall be used whenever the inquiry, pro-
ment:
posal,contract,order,orspecificationstatesthatausteniticsteel
SNT-TC-1A Recommended Practice for Nondestructive
forgings are to be subject to ultrasonic examination in accor-
Personnel Qualification and Certification
dance with Practice A745/A745M. Ultrasonic examination of
nonmagneticretainingringforgingsshouldbemadetoPractice
3. Ordering Information
A531/A531M, not to this practice.
3.1 When this practice is to be applied to an inquiry or
1.3 The values stated in either SI units or inch-pound units
purchase order, the purchaser shall furnish the following
are to be regarded separately as standard. The values stated in
information:
each system may not be exact equivalents; therefore, each
3.1.1 Quality level of examination (see Section 12).
system shall be used independently of the other. Combining
3.1.2 Additional requirements to this practice.
values from the two systems may result in non-conformance
3.1.3 Applicability of supplementary requirements (see
with the standard.
Supplementary Requirements section).
1.4 This practice and the applicable material specifications
3.2 When specified, the manufacturer shall submit an ex-
are expressed in both inch-pound units and SI units. However,
amination procedure for purchaser approval that shall include,
unless the order specifies the applicable “M” specification
but not be limited to, a sketch of the configuration as presented
designation [SI units], the material shall be furnished to
for ultrasonic examination showing the surfaces to be scanned,
inch-pound units.
scanning directions, notch locations and sizes (if applicable),
1.5 This standard does not purport to address all of the
extent of coverage (if applicable), and an instruction listing
safety concerns, if any, associated with its use. It is the
calibration and inspection details and stage of manufacture.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Apparatus
bility of regulatory limitations prior to use.
4.1 An electronic, pulsed, reflection type of instrument shall
2. Referenced Documents be used for this examination. The system shall have a mini-
3 mum capability for operating at frequencies from 0.5 to 5.0
2.1 ASTM Standards:
MHz. Either video or r-f presentation is acceptable.
A531/A531M Practice for Ultrasonic Examination of
4.2 The ultrasonic instrument shall provide linear presenta-
Turbine-Generator Steel Retaining Rings
tion (within 6 5 % of the signal height) for at least 75 % of the
E317 Practice for Evaluating Performance Characteristics
screen height (sweep line to top of screen). This 5 % linearity
of Ultrasonic Pulse-Echo Testing Instruments and Systems
is descriptive of the screen presentation of amplitude. Instru-
ment linearity shall be verified in accordance with the intent of
Practice E317.
This practice is under the jurisdiction of ASTM Committee A01 on Steel,
4.3 Instruments with incremental gain control (accurate
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
over its useful range to 6 10 % of the nominal attenuation
Current edition approved April 1, 2009. Published April 2009. Originally
ratio) shall be used when possible to allow measurement of
approved in 1977. Last previous edition approved in 2003 as A745/A745M – 94
signals beyond the linear display range of the instrument.
(2003). DOI: 10.1520/A0745_A0745M-94R09.
4.4 Search Units:
For ASME Boiler and Pressure Vessel Code applications see related Specifi-
cation SA-745/SA-745M in Section II of that Code.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from the American Society for Nondestructive Testing, 1711 Arlin-
the ASTM website. gate Lane, P.O. Box 28518, Columbus, OH 43228–0518.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A745/A745M–94 (2009)
4.4.1 Search units having transducers of either quartz or 6.5 In certain cases, such as with contour forged parts, it
other piezoelectric materials may be employed. may be impractical to assure 100 % volumetric coverage. Such
4.4.2 The maximum nominal active area of 1 ⁄2 in. [970 forgings shall be examined to the maximum extent possible.A
1 1
mm ] with ⁄2-in. [13 mm] minimum to 1 ⁄8-in. [30 mm] procedure indicating the extent of examination coverage shall
maximum dimensions or ⁄4-in. [20 mm] diameter minimum be submitted for the purchaser’s approval (see 3.2).
dimension shall be used for straight-beam scanning.
4.4.3 Angle-beam scanning transducers shall have a nomi-
7. Procedure
2 2
nalactiveareaof ⁄2to1in. [325to650mm ].Thesearchunit
7.1 Perform the ultrasonic examination after heat treatment
used for angle-beam examination shall produce a beam angle
when the forging is machined to the ultrasonic configuration
of 30 to 70° in the material.
but prior to drilling holes, cutting keyways, tapers, grooves, or
4.4.4 Other search units, including frequencies other than
machining sections to final contour.
those listed in Section 8 , may be used for evaluating and
7.2 To ensure complete coverage of the forging volume
pinpointing indications of discontinuities.
whenscanning,indexthesearchunitwithatleast15 %overlap
4.5 Couplant—A suitable couplant having good wetting
with each pass.
characteristics shall be used between the transducer and the
7.3 The scanning rate shall not exceed 6 in. [150 mm]/s.
examination surface. The same couplant shall be used for
7.4 Scan all regions of the forging in at least two perpen-
calibration and examination.
dicular directions to the maximum extent possible.
4.6 Reference Blocks:
7.5 Scan disk and disk-type forgings using a straight beam
4.6.1 All ultrasonic standard reference blocks shall be in
from at least one flat face and radially from the circumference
accordance with the general guidelines of Practice E428.
when practicable. For the purposes of this practice, a disk is a
However, absolute conformance to Practice E428 is not man-
cylindrical shape where the diameter dimension exceeds the
datory due to the nature of the material covered by this
height dimension. Disk-type forgings made as upset-forged
practice.
“pancakes” shall be classified as disks for inspection purposes
4.6.2 The reference block grain size, as measured by the
although at the time of inspection, the part may have a center
relative acoustic penetrability of the reference blocks, should
hole, counterturned steps, or other detail configuration.
be reasonably similar to the forging under examination. How-
ever, it must be recognized that large austenitic forgings vary 7.6 Scan cylindrical sections, ring and hollow forgings from
considerably in acoustic penetrability throughout their volume the entire external surface (sides or circumference), using the
due to variations in grain size and structure. Reference blocks straight-beam technique, and scan the forging in the axial
should be chosen that reasonably approximate the average direction to the extent possible.When the length divided by the
penetrability of the forging under examination. Supplementary diameterratio(slendernessratio)exceeds6to1(oraxiallength
blocks of coarser or finer grain may be used for evaluation of exceeds 24 in. [600 mm]), scan axially from both end surfaces
indications as covered in Section 11. to the extent possible. If axial penetration is not possible due to
4.6.3 As an alternative method, where practicable, the attenuation, angle-beam examination directed axially may be
appropriate size of reference hole (or holes) or notches may be
substituted in place of axial straight beam. Examine ring and
placed in representative areas of the forging for calibration and hollow forgings having an outside-diameter to inside-diameter
examination purposes when removed by subsequent machin-
ratio of less than 2 to 1 and a wall thickness less than 8 in. [200
ing. When holes or notches are not removed by subsequent mm] by angle-beam techniques from the outside diameter or
machining, the purchaser must approve the location of holes or
inside diameter, or both, using full node or half-node technique
notches. (see 10.1.2 and 10.1.3) as necessary to achieve either 100 %
volumetric coverage or the extent of coverage defined by an
5. Personnel Requirements
approved procedure (see 3.2).
5.1 Personnelperformingtheultrasonicexaminationstothis
practice shall be qualified and certified in accordance with a
8. Examination Frequency
written procedure conforming to Recommended Practice No.
8.1 Perform all ultrasonic examination at the highest fre-
SNT-TC-1A or another national standard that is acceptable to
quency practicable (as specified in 8.1.1, 8.1.2,or 8.1.3) that
both the purchaser and the supplier.
will adequately penetrate the forging thickness and resolve the
applicable reference standard. Include in the ultrasonic exami-
6. Forging Conditions
nation report the examination frequency used. Determine the
6.1 Forgings shall be ultrasonically examined after heat
test frequency at the time of actual examination by the
treating.
following guidelines:
6.2 The surfaces of the forging to be examined shall be free
8.1.1 The nominal test frequency shall be 2.25 MHz. Use of
of extraneous material such as loose scale, paint, dirt, etc.
this frequency will generally be restricted due to attenuation.
6.3 The surface roughness of scanning surfaces shall not
8.1.2 Onemegahertzisacceptableandwillbethefrequency
exceed 250 µin. [6 µm] unless otherwise stated in the order or
generally applicable.
contract.
6.4 The forgings shall be machined to a simple configura- 8.1.3 When necessary, due to attenuation, 0.5-MHz exami-
tion, that is, rectangular or parallel or concentric surfaces nation frequency may be used. The purchaser may request
where complete volumetric coverage can be obtained. notification before this lower frequency is employed.
A745/A745M–94 (2009)
8.1.4 In the event that adequate penetration of certain 3 in. [75 mm] ⁄2 T, and T. However, the distance between any
regions is not possible even at 0.5 MHz, alternative nonde- of the test blocks shall be 1 ⁄2 in. [40 mm] minimum. If
structive examination methods (such as radiography) may be indications closer than 3 in. [75 mm] from the initial pulse
employed to ensure the soundness of the forging by agreement must be evaluated, an additional block with 1 ⁄2 in. [40 mm]
between the purchaser and the manufacturer. test metal distance shall be used. This is the fixed reference
against which all indications shall be evaluated at the maxi-
9. Straight-Beam Examination
mum obtainable response at whatever depth the indications are
9.1 Method of Calibration:
observed. This will constitute an acceptable examination if
9.1.1 Perform calibration for straight-beam examination on
there are no indications exceeding the acceptance limits. In
the flat-bottom hole size determined by the applicable quality
large forgings, it is expected that a portion of the distance-
level (see Section 12).
amplitudecurvewillbeabovetheverticallinearitylimitsofthe
9.1.2 Determine the calibration method by the test metal
instrument. If an indication appears in this area, readjust the
distance involved.
instrument through the use of a calibrated gain control or
9.1.2.1 Thicknesses up to 6 in. [150 mm] may be examined
through recalibration to the initial calibration level to bring the
using either the single-block or the distance-amplitude curve
appropriate portion of the presentation on screen for evaluation
calibration method.
of that specific area.
(a) (a) Single-Block Method—Establish the test sensitiv-
NOTE 1—When flat surfaced reference block calibration is used for
ity on the reference standard representing the forging thick-
examination of forgings with surface curvature, compensation for curva-
ness. Drill flat-bottom holes normal to the examining surface,
ture shall be made and the method for curvature correction shall be a
tomidsectioninmaterialupto1.5in.[40mm]inthicknessand
matter of agreement between the producer and the purchaser. For
at least 0.75 in. [20 mm] in depth but no deeper than
diameters 80 in. [2000 mm] and over, no correction factor is required.
midsection in thicknesses from 1.5 to 6 in. [40 to 150 mm].
Make evaluations of indications at the estimated discontinuity
10. Angle-Beam Examination
depth at which they are observed using supplementary refer-
10.1 Ringandhollowroundforgings,asdefinedin7.6,shall
ence standards, if necessary.
be angle-beam examined from their outer periphery in both
(b) (b) Distance-Amplitude-Curve Correction Method—
circumferential directions employing the following method of
Establish the test sensitivity on the reference standard whose
calibration:
metal travel distance represents the greater metal travel dis-
10.1.1 Notches of 1.25 in. [30 mm] maximum surface
tance of the part under examination, within 61 in. [25 mm].
length, with the length perpendicular to sound propagation;
9.1.2.2 Examine thicknesses from 6 to 24 in. [150 to 600
depth based on quality level (Section12), either rectangular
mm] using the distance-amplitude calibration method. Calibra-
with a width not greater than twice its depth or 60° minimum
tion to ⁄2 thickness test metal distance may be used provided
to 75° maximum included angle, located in the forging so as to
examinations from two opposing surfaces are made.
produce no interference with each other, shall be used as
9.1.2.3 For metal travel distances over 24 in. [600 mm],
calibration standards.
perform one of the following e
...
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:A 745/A 745M–94 (Reapproved 2003) Designation: A745/A745M – 94
(Reapproved 2009)
Standard Practice for
Ultrasonic Examination of Austenitic Steel Forgings
This standard is issued under the fixed designationA745/A745M; 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
1.1 This practice covers the standards and procedures for the contact, pulse-echo ultrasonic examination of austenitic steel
forgings by the straight or angle beam techniques, or both.
1.2 This practice shall be used whenever the inquiry, proposal, contract, order, or specification states that austenitic steel
forgings are to be subject to ultrasonic examination in accordance with Practice A745/A745M. Ultrasonic examination of
nonmagnetic retaining ring forgings should be made to Practice A 531A531/A531M, not to this practice.
1.3 The values stated in either inch-pound SI units or SIinch-pound units are to be regarded separately as standard. Within the
text, the SI units are shown in brackets. The values stated in each system aremay not be exact equivalents; therefore, each system
mustshall be used independently of the other. Combining values from the two systems may result in non-conformance with the
practice. standard.
1.4 Thispracticeandtheapplicablematerialspecificationsareexpressedinbothinch-poundunitsandSIunits.However,unless
the order specifies the applicable “M” specification designation [SI units], the material shall be furnished to inch-pound units.
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.
2. Referenced Documents
2.1 ASTM Standards:
A531/A531M Practice for Ultrasonic InspectionExamination of Turbine-Generator Steel Retaining Rings
E317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-Echo ExaminationTesting Instruments and
Systems Withoutwithout the Use of Electronic Measurement Instruments
E428 Practice for Fabrication and Control of Steel Metal, Other than Aluminum, Reference Blocks Used in Ultrasonic
ExaminationTesting
2.2
2.2 American Society for Nondestructive Testing Document:
SNT-TC-1ARecommended Recommended Practice for Nondestructive Personnel Qualification and Certification
3. Ordering Information
3.1 When this practice is to be applied to an inquiry or purchase order, the purchaser shall furnish the following information:
3.1.1 Quality level of examination (see Section 12).
3.1.2 Additional requirements to this practice.
3.1.3 Applicability of supplementary requirements (see Supplementary Requirements section).
3.2 When specified, the manufacturer shall submit an examination procedure for purchaser approval that shall include, but not
be limited to, a sketch of the configuration as presented for ultrasonic examination showing the surfaces to be scanned, scanning
directions, notch locations and sizes (if applicable), extent of coverage (if applicable), and an instruction listing calibration and
inspection details and stage of manufacture.
This practice is under the jurisdiction ofASTM CommitteeA01 on Steel, Stainless Steel,Steel and RelatedAlloys,Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
Current edition approved Oct. 1, 2003. Published November 2003. Originally approved in 1977. Last previous edition approved in 1999 as A 745–94(1999).
Current edition approved April 1, 2009. Published April 2009. Originally approved in 1977. Last previous edition approved in 2003 as A745/A745M – 94 (2003). DOI:
10.1520/A0745_A0745M-94R09.
For ASME Boiler and Pressure Vessel Code applications see related Specification SA-745/SA-745M in Section II of that Code.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from the American Society for Nondestructive Testing, 1711 Arlingate Lane, P.O. Box 28518, Columbus, OH 43228–0518.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A745/A745M – 94 (2009)
4. Apparatus
4.1 An electronic, pulsed, reflection type of instrument shall be used for this examination. The system shall have a minimum
capability for operating at frequencies from 0.5 to 5.0 MHz. Either video or r-f presentation is acceptable.
4.2 Theultrasonicinstrumentshallprovidelinearpresentation(within 65 %ofthesignalheight)foratleast75 %ofthescreen
height (sweep line to top of screen). This 5 % linearity is descriptive of the screen presentation of amplitude. Instrument linearity
shall be verified in accordance with the intent of Practice E 317E317.
4.3 Instruments with incremental gain control (accurate over its useful range to 6 10 % of the nominal attenuation ratio) shall
be used when possible to allow measurement of signals beyond the linear display range of the instrument.
4.4 Search Units:
4.4.1 Search units having transducers of either quartz or other piezoelectric materials may be employed.
2 2
1 1 1
4.4.2 The maximum nominal active area of 1 ⁄2 in. [970 mm ] with ⁄2-in. [13 mm] minimum to 1 ⁄8-in. [30 mm] maximum
dimensions or ⁄4-in. [20 mm] diameter minimum dimension shall be used for straight-beam scanning.
2 2
4.4.3 Angle-beam scanning transducers shall have a nominal active area of ⁄2 to 1 in. [325 to 650 mm ]. The search unit used
for angle-beam examination shall produce a beam angle of 30 to 70° in the material.
4.4.4 Other search units, including frequencies other than those listed in Section 8 , may be used for evaluating and pinpointing
indications of discontinuities.
4.5 Couplant—A suitable couplant having good wetting characteristics shall be used between the transducer and the
examination surface. The same couplant shall be used for calibration and examination.
4.6 Reference Blocks:
4.6.1 All ultrasonic standard reference blocks shall be in accordance with the general guidelines of Practice E 428E428.
However, absolute conformance to Practice E 428E428 is not mandatory due to the nature of the material covered by this practice.
4.6.2 The reference block grain size, as measured by the relative acoustic penetrability of the reference blocks, should be
reasonably similar to the forging under examination. However, it must be recognized that large austenitic forgings vary
considerably in acoustic penetrability throughout their volume due to variations in grain size and structure. Reference blocks
should be chosen that reasonably approximate the average penetrability of the forging under examination. Supplementary blocks
of coarser or finer grain may be used for evaluation of indications as covered in Section 11.
4.6.3 As an alternative method, where practicable, the appropriate size of reference hole (or holes) or notches may be placed
in representative areas of the forging for calibration and examination purposes when removed by subsequent machining. When
holes or notches are not removed by subsequent machining, the purchaser must approve the location of holes or notches.
5. Personnel Requirements
5.1 Personnelperformingtheultrasonicexaminationstothispracticeshallbequalifiedandcertifiedinaccordancewithawritten
procedure conforming to Recommended Practice No. SNT-TC-1A SNT-TC-1Aor another national standard that is acceptable to
both the purchaser and the supplier.
6. Forging Conditions
6.1 Forgings shall be ultrasonically examined after heat treating.
6.2 The surfaces of the forging to be examined shall be free of extraneous material such as loose scale, paint, dirt, etc.
6.3 The surface roughness of scanning surfaces shall not exceed 250 µin. [6 µm] unless otherwise stated in the order or contract.
6.4 The forgings shall be machined to a simple configuration, that is, rectangular or parallel or concentric surfaces where
complete volumetric coverage can be obtained.
6.5 Incertaincases,suchaswithcontourforgedparts,itmaybeimpracticaltoassure100 %volumetriccoverage.Suchforgings
shall be examined to the maximum extent possible.Aprocedure indicating the extent of examination coverage shall be submitted
for the purchaser’s approval (see 3.2).
7. Procedure
7.1 Perform the ultrasonic examination after heat treatment when the forging is machined to the ultrasonic configuration but
prior to drilling holes, cutting keyways, tapers, grooves, or machining sections to final contour.
7.2 To ensure complete coverage of the forging volume when scanning, index the search unit with at least 15 % overlap with
each pass.
7.3 The scanning rate shall not exceed 6 in. [150 mm]/s.
7.4 Scan all regions of the forging in at least two perpendicular directions to the maximum extent possible.
7.5 Scan disk and disk-type forgings using a straight beam from at least one flat face and radially from the circumference when
practicable. For the purposes of this practice, a disk is a cylindrical shape where the diameter dimension exceeds the height
dimension. Disk-type forgings made as upset-forged “pancakes” shall be classified as disks for inspection purposes although at the
time of inspection, the part may have a center hole, counterturned steps, or other detail configuration.
7.6 Scan cylindrical sections, ring and hollow forgings from the entire external surface (sides or circumference), using the
straight-beam technique, and scan the forging in the axial direction to the extent possible.When the length divided by the diameter
ratio (slenderness ratio) exceeds 6 to 1 (or axial length exceeds 24 in. [600 mm]), scan axially from both end surfaces to the extent
A745/A745M – 94 (2009)
possible.Ifaxialpenetrationisnotpossibleduetoattenuation,angle-beamexaminationdirectedaxiallymaybesubstitutedinplace
of axial straight beam. Examine ring and hollow forgings having an outside-diameter to inside-diameter ratio of less than 2 to 1
andawallthicknesslessthan8in.[200mm]byangle-beamtechniquesfromtheoutsidediameterorinsidediameter,orboth,using
full node or half-node technique (see 10.1.2 and 10.1.3) as necessary to achieve either 100 % volumetric coverage or the extent
of coverage defined by an approved procedure (see 3.2).
8. Examination Frequency
8.1 Perform all ultrasonic examination at the highest frequency practicable (as specified in 8.1.1, 8.1.2, or 8.1.3) that will
adequately penetrate the forging thickness and resolve the applicable reference standard. Include in the ultrasonic examination
report the examination frequency used. Determine the test frequency at the time of actual examination by the following guidelines:
8.1.1 The nominal test frequency shall be 2.25 MHz. Use of this frequency will generally be restricted due to attenuation.
8.1.2 One megahertz is acceptable and will be the frequency generally applicable.
8.1.3 Whennecessary,duetoattenuation,0.5-MHzexaminationfrequencymaybeused.Thepurchasermayrequestnotification
before this lower frequency is employed.
8.1.4 In the event that adequate penetration of certain regions is not possible even at 0.5 MHz, alternative nondestructive
examination methods (such as radiography) may be employed to ensure the soundness of the forging by agreement between the
purchaser and the manufacturer.
9. Straight-Beam Examination
9.1 Method of Calibration:
9.1.1 Perform calibration for straight-beam examination on the flat-bottom hole size determined by the applicable quality level
(see Section 12).
9.1.2 Determine the calibration method by the test metal distance involved.
9.1.2.1 Thicknesses up to 6 in. [150 mm] may be examined using either the single-block or the distance-amplitude curve
calibration method.
(a) (a) Single-Block Method—Establish the test sensitivity on the reference standard representing the forging thickness. Drill
flat-bottom holes normal to the examining surface, to midsection in material up to 1.5 in. [40 mm] in thickness and at least 0.75
in. [20 mm] in depth but no deeper than midsection in thicknesses from 1.5 to 6 in. [40 to 150 mm]. Make evaluations of
indications at the estimated discontinuity depth at which they are observed using supplementary reference standards, if necessary.
(b) (b) Distance-Amplitude-Curve Correction Method—Establish the test sensitivity on the reference standard whose metal
travel distance represents the greater metal travel distance of the part under examination, within 61 in. [25 mm].
9.1.2.2 Examine thicknesses from 6 to 24 in. [150 to 600 mm] using the distance-amplitude calibration method. Calibration to
⁄2 thickness test metal distance may be used provided examinations from two opposing surfaces are made.
9.1.2.3 For metal travel distances over 24 in. [600 mm], perform one of the following examinations:
(a) (a) Perform a back-reflection examination from at least one surface to QL-5 (see 12.1.1) or to a purchaser-approved
procedure (see 3.2).
(b) (b) On hollow-round forgings with wall thicknesses less than 8 in. [200 mm], perform an axial angle-beam scan in place
of the straight-beam scan from the end surfaces. Calibration for this scan may be established on the existing axial notches required
for the circumferential scan or on transverse oriented notches installed specifically for axial angle beam.
9.2 Calibration Procedure—Over an indication-free area of the forging and with the proper test frequency, adjust the amplitude
of the back reflection to the maximum limit of vertical linearity of the instrument.The adjusted instrument sensitivity display shall
be the primary calibration reference for both the single-block and multiple-block calibration methods. If, at this gain setting, the
amplitude response from the flat-bottom hole in the longest calibration block is not equal to or greater than 0.5 in. [13 mm]
sweep-to-peak, adjust the instrument gain further to obtain a 0.5-in. [13 mm] sweep-to-peak minimum response. To complete the
distance-amplitude correction curve, determine the remaining points defining the shape of the curve at this adjusted gain setting
and mark the curve on the s
...
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