ASTM A745/A745M-94(1999)
(Practice)Standard Practice for Ultrasonic Examination of Austenitic Steel Forgings
Standard Practice for Ultrasonic Examination of Austenitic Steel Forgings
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 A531, not to this practice.
1.3 The values stated in either inch-pound or SI units are to be regarded as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the practice.
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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Standards Content (Sample)
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Designation: A 745/A 745M – 94 (Reapproved 1999)
Standard Practice for
Ultrasonic Examination of Austenitic Steel Forgings
This standard is issued under the fixed designation A 745/A 745M; 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 428 Practice for Fabrication and Control of Steel Refer-
ence Blocks Used in Ultrasonic Inspection
1.1 This practice covers the standards and procedures for
2.2 American Society for Nondestructive Testing Docu-
the contact, pulse-echo ultrasonic examination of austenitic
ment:
steel forgings by the straight or angle beam techniques, or both.
SNT-TC-1A Recommended Practice for Nondestructive
1.2 This practice shall be used whenever the inquiry, pro-
Personnel Qualification and Certification
posal, contract, order, or specification states that austenitic steel
forgings are to be subject to ultrasonic examination in accor-
3. Ordering Information
dance with Practice A 745/A 745M. Ultrasonic examination of
3.1 When this practice is to be applied to an inquiry or
nonmagnetic retaining ring forgings should be made to Practice
purchase order, the purchaser shall furnish the following
A 531, not to this practice.
information:
1.3 The values stated in either inch-pound or SI units are to
3.1.1 Quality level of examination (see Section 12).
be regarded as standard. Within the text, the SI units are shown
3.1.2 Additional requirements to this practice.
in brackets. The values stated in each system are not exact
3.1.3 Applicability of supplementary requirements (see
equivalents; therefore, each system must be used indepen-
Supplementary Requirements section).
dently of the other. Combining values from the two systems
3.2 When specified, the manufacturer shall submit an ex-
may result in nonconformance with the practice.
amination procedure for purchaser approval that shall include,
1.4 This practice and the applicable material specifications
but not be limited to, a sketch of the configuration as presented
are expressed in both inch-pound units and SI units. However,
for ultrasonic examination showing the surfaces to be scanned,
unless the order specifies the applicable “M” specification
scanning directions, notch locations and sizes (if applicable),
designation [SI units], the material shall be furnished to
extent of coverage (if applicable), and an instruction listing
inch-pound units.
calibration and inspection details and stage of manufacture.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Apparatus
responsibility of the user of this standard to establish appro-
4.1 An electronic, pulsed, reflection type of instrument shall
priate safety and health practices and determine the applica-
be used for this examination. The system shall have a mini-
bility of regulatory limitations prior to use.
mum capability for operating at frequencies from 0.5 to 5.0
MHz. Either video or r-f presentation is acceptable.
2. Referenced Documents
4.2 The ultrasonic instrument shall provide linear presenta-
2.1 ASTM Standards:
tion (within 6 5 % of the signal height) for at least 75 % of the
A 531/A531M Practice for Ultrasonic Inspection of
3 screen height (sweep line to top of screen). This 5 % linearity
Turbine-Generator Steel Retaining Rings
is descriptive of the screen presentation of amplitude. Instru-
E 317 Practice for Evaluating Performance Characteristics
ment linearity shall be verified in accordance with the intent of
of Ultrasonic Pulse-Echo Testing Systems Without the Use
4 Practice E 317.
of Electronic Measurement Instruments
4.3 Instruments with incremental gain control (accurate
over its useful range to 6 10 % of the nominal attenuation
This practice is under the jurisdiction of ASTM Committee A-1 on Steel, ratio) shall be used when possible to allow measurement of
Stainless Steel, and Related Alloys, and is the direct responsibility of Subcommittee
signals beyond the linear display range of the instrument.
A01.06 on Steel Forgings and Billets.
4.4 Search Units:
Current edition approved Aug. 15, 1994. Published October 1994. Originally
published as A 745 – 77. Last previous edition A 745 – 86 (1991).
For ASME Boiler and Pressure Vessel Code applications see related Specifi-
cation SA-745/SA-745M in Section II of that Code.
3 5
Annual Book of ASTM Standards, Vol 01.05. Available from the American Society for Nondestructive Testing, 1711 Arlin-
Annual Book of ASTM Standards, Vol 03.03. 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.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
A 745/A 745M – 94 (1999)
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
nal active area of ⁄2 to 1 in. [325 to 650 mm ]. The search unit
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.
when scanning, index the search unit with at least 15 % 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 E 428.
when practicable. For the purposes of this practice, a disk is a
However, absolute conformance to Practice E 428 is not
cylindrical shape where the diameter dimension exceeds the
mandatory 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
diameter ratio (slenderness ratio) exceeds 6 to 1 (or axial length
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 Personnel performing the ultrasonic examinations to this
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 One megahertz is acceptable and will be the frequency
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.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
A 745/A 745M – 94 (1999)
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).
amplitude curve will be above the vertical linearity limits of the
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
to midsection in material up to 1.5 in. [40 mm] in thickness and
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 Ring and hollow round forgings, as defined in 7.6, 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
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