ASTM A745/A745M-20

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: A745/A745M − 15 A745/A745M − 20
Standard Practice for
Ultrasonic Examination of Austenitic Steel Forgings
This standard is issued under the fixed designation A745/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 straight and angle beam contact, pulse-echo ultrasonic examination of austenitic steel forgings
produced in accordance with Practice A388/A388M and Specifications A965/A965M and A1049/A1049M.
1.2 Ultrasonic examination of nonmagnetic retaining ring forgings should be made to Practice A531/A531M rather than this
practice.
1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementary
requirements shall apply only when specified individually by the purchaser in the purchase order or contract.
1.4 This practice is expressed in inch-pound and SI units; however, unless the purchase order or contract specifies the applicable
“M” specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-pound units or SI units
are to be regarded separately as standard. Within the practice, the SI units are shown in brackets. The values stated in each system
mayare not benecessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other. Combiningother, and values from the two systems may result in nonconformance with the
standard.shall not be combined.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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:
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A531/A531M Practice for Ultrasonic Examination of Turbine-Generator Steel Retaining Rings
A788/A788M Specification for Steel Forgings, General Requirements
A965/A965M Specification for Steel Forgings, Austenitic, for Pressure and High Temperature Parts
A1049/A1049M Specification for Stainless Steel Forgings, Ferritic/Austenitic (Duplex), for Pressure Vessels and Related
Components
E317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-Echo Testing Instruments and Systems without the
Use of Electronic Measurement Instruments
E428 Practice for Fabrication and Control of Metal, Other than Aluminum, Reference Blocks Used in Ultrasonic Testing
(Withdrawn 2019)
2.2 ASME Code:
ASME Boiler and Pressure Vessel Code
This practice is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06
on Steel Forgings and Billets.
Current edition approved May 1, 2015May 1, 2020. Published May 2015June 2020. Originally approved in 1977. Last previous edition approved in 20122015 as
A745/A745M – 12.A745/A745M-15. DOI: 10.1520/A0745_A0745M-15.10.1520/A0745_A0745M-20.
For ASME Boiler and Pressure Vessel Code applications, see related Specification 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’sstandard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
www.asme.org.
*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
A745/A745M − 20
2.3 American Society for Nondestructive Testing Document:
SNT-TC-1A 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).
3.1.4 Supplementary requirements, if any.
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.
4. Apparatus
4.1 Electronic Apparatus—A pulse-echo instrument permitting inspection frequencies of 1, 2.25,1 MHz, 2.25 MHz, and 5 MHz
is required. The accuracy of discontinuity amplitude analysis using this practice involves a knowledge of the true operating
frequency of the complete inspection system. One of the best ways to obtain the desired accuracy is by use of a tuned pulser and
narrow band amplifier of known frequency response, with either a broadband transducer, or a narrow-band tuned transducer of
known and matching frequency.
4.1.1 Apparatus Qualification and Calibration—Basic qualification of the ultrasonic test instrument shall be performed at
intervals not to exceed 12 months or whenever maintenance is performed that affects the equipment function. The date of the last
calibration and the date of the next required calibration shall be displayed on the test equipment.
4.1.2 The horizontal linearity shall be checked on a distance calibration bar using the multiple order technique (see Practice
E317). The horizontal linearity shall be 62 % of the metal path.
4.1.3 The accuracy of the linearity shall be checked by ultrasonically verifying the thickness of the component in at least one
location beyond the near field of the transducer. If necessary, minor adjustments for differences in the ultrasonic velocities between
the calibration bar and the forging shall then be made.
4.2 Amplifier—The amplifier and display shall provide linear response within 62 %, up to 100 % of full screen height.
4.2.1 Amplifier Calibration—An amplifier vertical linearity check shall be made prior to performing the test by observing a
multiple order pattern from a calibration block using a 2.25 MHz 2.25 MHz transducer (see Practice E317). The first back reflection
shall be set at 100 % of full screen height. The higher order back reflections, 10 % and higher in amplitude, shall also be positioned
on the screen and their amplitudes noted. The first back reflection shall be reduced to 50 % and then 25 % of full screen height.
The amplitudes of the higher order back reflections shall be noted at each step. The vertical linearity will be considered acceptable
if the signal heights of the higher order reflections decrease in proportion to the decrease set for the first back reflection. The
maximum acceptable error for the decrease of the higher order reflections is the greater of 65 % of the expected back reflection
height or 62 % of full screen height.
4.3 Signal Attenuator—The instrument shall contain a calibrated gain control or signal attenuator that meets the requirements
of Practice E317 (in each case, accurate within 65 %) that will allow indications beyond the linear range of the instrument to be
measured. It is recommended that these controls permit signal adjustments up to 25 to 1 (28 dB).
4.4 Search Units:
2 2
1 1 1
4.4.1 The maximum nominal active area of 1 ⁄2 in. [970 mm[970 mm ] with ⁄2-in. in. [13 mm] minimum to 1 ⁄8-in. in. [30 mm]
maximum dimensions or ⁄4-in. in. [20 mm] diameter minimum dimension shall be used for straight-beam scanning.
2 2
4.4.2 Angle-beam scanning transducers shall have a nominal active area of ⁄2 in. to 1 in. [325[325 mm to 650 mm ]. The
search unit used for angle-beam examination shall produce a beam angle of 30 to 70° in the material.
4.4.3 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 E428. However,
absolute conformance to Practice E428 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
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
A745/A745M − 20
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 Personnel performing the ultrasonic examinations to this practice shall be qualified and certified in accordance with a written
procedure conforming to Recommended Practice No. SNT-TC-1A or 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
where the definition for surface finish is as per Specification A788/A788M.
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 In certain cases, such as with contour forged parts, it may be impractical to assure 100 % volumetric coverage. Such forgings
shall be examined to the maximum extent possible. A procedure indicating the extent of examination coverage shall be submitted
for the purchaser’spurchaser’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
possible. If axial penetration is not possible due to attenuation, angle-beam examination directed axially may be substituted in place
of axial straight beam. Examine ring and hollow forgings having an outside-diameter to inside-diameter ratio of less than 2 to 1
and a wall thickness less than 8 in. [200 mm] [200 mm] by angle-beam techniques from the outside diameter or inside diameter,
or both, 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).
7.7 If electronic circuitry is used for ultrasonic examination, the manufacturer’s instructions for the specific instrument shall
be required. This is achieved by the use of electronic circuitry referred to as time variable amplifier gain, typically called distance
amplitude correction (DAC), distance echo correction (DEC), time varying gain (TVG), time-corrected gain (TCG), or sensitivity
time control (STC). If circuitry is used that normalizes the amplitude of each reflector, such as TCG, the reflector with the lowest
response shall be set at 80 % FSH.
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
...