ASTM A745/A745M-94(2003)
(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, 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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Designation:A 745/A 745M–94 (Reapproved 2003)
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope A 531/A531M Practice for Ultrasonic Inspection of
2 Turbine-Generator Steel Retaining Rings
1.1 This practice covers the standards and procedures for
E 317 Practice for Evaluating Performance Characteristics
the contact, pulse-echo ultrasonic examination of austenitic
of Ultrasonic Pulse-Echo Examination Instruments and
steelforgingsbythestraightoranglebeamtechniques,orboth.
Systems Without the Use of Electronic Measurement
1.2 This practice shall be used whenever the inquiry, pro-
Instruments
posal,contract,order,orspecificationstatesthatausteniticsteel
E 428 Practice for Fabrication and Control of Steel Refer-
forgings are to be subject to ultrasonic examination in accor-
ence Blocks Used in Ultrasonic Examination
dance with PracticeA 745/A 745M. Ultrasonic examination of
2.2 American Society for Nondestructive Testing Docu-
nonmagneticretainingringforgingsshouldbemadetoPractice
ment:
A 531, not to this practice.
SNT-TC-1A Recommended Practice for Nondestructive
1.3 The values stated in either inch-pound or SI units are to
Personnel Qualification and Certification
be regarded as standard.Within the text, the SI units are shown
in brackets. The values stated in each system are not exact
3. Ordering Information
equivalents; therefore, each system must be used indepen-
3.1 When this practice is to be applied to an inquiry or
dently of the other. Combining values from the two systems
purchase order, the purchaser shall furnish the following
may result in nonconformance with the practice.
information:
1.4 This practice and the applicable material specifications
3.1.1 Quality level of examination (see Section 12).
are expressed in both inch-pound units and SI units. However,
3.1.2 Additional requirements to this practice.
unless the order specifies the applicable “M” specification
3.1.3 Applicability of supplementary requirements (see
designation [SI units], the material shall be furnished to
Supplementary Requirements section).
inch-pound units.
3.2 When specified, the manufacturer shall submit an ex-
1.5 This standard does not purport to address all of the
amination procedure for purchaser approval that shall include,
safety concerns, if any, associated with its use. It is the
but not be limited to, a sketch of the configuration as presented
responsibility of the user of this standard to establish appro-
for ultrasonic examination showing the surfaces to be scanned,
priate safety and health practices and determine the applica-
scanning directions, notch locations and sizes (if applicable),
bility of regulatory limitations prior to use.
extent of coverage (if applicable), and an instruction listing
2. Referenced Documents calibration and inspection details and stage of manufacture.
2.1 ASTM Standards:
4. Apparatus
4.1 An electronic, pulsed, reflection type of instrument shall
be used for this examination. The system shall have a mini-
This practice is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel, and RelatedAlloys, and is the direct responsibility of Subcommittee
mum capability for operating at frequencies from 0.5 to 5.0
A01.06 on Steel Forgings and Billets.
MHz. Either video or r-f presentation is acceptable.
Current edition approved Oct. 1, 2003. Published November 2003. Originally
4.2 The ultrasonic instrument shall provide linear presenta-
approved in 1977. Last previous edition approved in 1999 as A 745 – 94 (1999).
For ASME Boiler and Pressure Vessel Code applications see related Specifi- tion (within 6 5 % of the signal height) for at least 75 % of the
cation SA-745/SA-745M in Section II of that Code.
screen height (sweep line to top of screen). This 5 % linearity
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.
A 745/A 745M–94 (2003)
is descriptive of the screen presentation of amplitude. Instru- 6.2 The surfaces of the forging to be examined shall be free
ment linearity shall be verified in accordance with the intent of of extraneous material such as loose scale, paint, dirt, etc.
Practice E 317. 6.3 The surface roughness of scanning surfaces shall not
4.3 Instruments with incremental gain control (accurate exceed 250 µin. [6 µm] unless otherwise stated in the order or
over its useful range to 6 10 % of the nominal attenuation contract.
ratio) shall be used when possible to allow measurement of 6.4 The forgings shall be machined to a simple configura-
signals beyond the linear display range of the instrument.
tion, that is, rectangular or parallel or concentric surfaces
4.4 Search Units: where complete volumetric coverage can be obtained.
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 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-
7.6 Scan cylindrical sections, ring and hollow forgings from
ever, it must be recognized that large austenitic forgings vary
the entire external surface (sides or circumference), using the
considerably in acoustic penetrability throughout their volume
straight-beam technique, and scan the forging in the axial
due to variations in grain size and structure. Reference blocks
direction to the extent possible.When the length divided by the
should be chosen that reasonably approximate the average
diameterratio(slendernessratio)exceeds6to1(oraxiallength
penetrability of the forging under examination. Supplementary
exceeds 24 in. [600 mm]), scan axially from both end surfaces
blocks of coarser or finer grain may be used for evaluation of
to the extent possible. If axial penetration is not possible due to
indications as covered in Section 11.
attenuation, angle-beam examination directed axially may be
4.6.3 As an alternative method, where practicable, the
substituted in place of axial straight beam. Examine ring and
appropriate size of reference hole (or holes) or notches may be
hollow forgings having an outside-diameter to inside-diameter
placed in representative areas of the forging for calibration and
ratio of less than 2 to 1 and a wall thickness less than 8 in. [200
examination purposes when removed by subsequent machin-
mm] by angle-beam techniques from the outside diameter or
ing. When holes or notches are not removed by subsequent
inside diameter, or both, using full node or half-node technique
machining, the purchaser must approve the location of holes or
(see 10.1.2 and 10.1.3) as necessary to achieve either 100 %
notches.
volumetric coverage or the extent of coverage defined by an
approved procedure (see 3.2).
5. Personnel Requirements
5.1 Personnelperformingtheultrasonicexaminationstothis
8. Examination Frequency
practice shall be qualified and certified in accordance with a
8.1 Perform all ultrasonic examination at the highest fre-
written procedure conforming to Recommended Practice No.
quency practicable (as specified in 8.1.1, 8.1.2, or 8.1.3) that
SNT-TC-1A or another national standard that is acceptable to
will adequately penetrate the forging thickness and resolve the
both the purchaser and the supplier.
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:
A 745/A 745M–94 (2003)
8.1.1 The nominal test frequency shall be 2.25 MHz. Use of or greater than 0.5 in. [13 mm] sweep-to-peak, adjust the
this frequency will generally be restricted due to attenuation. instrument gain further to obtain a 0.5-in. [13 mm] sweep-to-
8.1.2 Onemegahertzisacceptableandwillbethefrequency peak minimum response. To complete the distance-amplitude
generally applicable. correction curve, determine the remaining points defining the
8.1.3 When necessary, due to attenuation, 0.5-MHz exami- shape of the curve at this adjusted gain setting and mark the
nation frequency may be used. The purchaser may request curve on the shield of the cathode ray tube or plot on a graph.
notification before this lower frequency is employed. At least three blocks shall be used with test metal distances of
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 me
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