ASTM A966/A966M-15
(Practice)Standard Practice for Magnetic Particle Examination of Steel Forgings Using Alternating Current
Standard Practice for Magnetic Particle Examination of Steel Forgings Using Alternating Current
SIGNIFICANCE AND USE
5.1 For ferromagnetic materials, magnetic particle examination is widely specified for the detection of surface and near-surface flaws such as cracks, laps, seams, and linearly oriented nonmetallic inclusions. Such examinations are included as mandatory requirements in some forging standards such as Specifications A508/A508M and A963/A963M.
5.2 Use of alternating current as the power source for magnetic particle examination imposes a significant restriction on the detection of subsurface indications, so that the procedure is essentially limited to the finding of flaws that are open to the surface. Attention therefore is drawn to the need to have the component in the finish-machined condition before conducting the magnetic particle examination.
5.3 The presence of residual magnetic fields in a component may be undesirable, and an advantage of the use of an AC power source for magnetic particle examination is that an acceptable level of demagnetization can be readily achieved.
SCOPE
1.1 This practice covers a procedure for the magnetic particle examination of steel forgings using alternating current as the power source. The procedure will produce consistent results upon which acceptance standards can be based. This practice does not contain acceptance limits or recommended quality levels.
1.2 Only alternating 50–60 cycle current shall be used as the electric power source for any of the magnetizing methods.
1.3 When subsurface indications are sought in forgings, then dc magnetization in accordance with Practice A275/A275M should be used.
1.4 The values stated in either inch-pound units or SI units are to be regarded separately 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 shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. Unless the order specifies the applicable “M” specification designation [SI units], the inch-pound units shall be used.
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: A966/A966M − 15
Standard Practice for
Magnetic Particle Examination of Steel Forgings Using
1
Alternating Current
This standard is issued under the fixed designationA966/A966M; 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* A508/A508M Specification for Quenched and Tempered
Vacuum-Treated Carbon and Alloy Steel Forgings for
1.1 This practice covers a procedure for the magnetic
Pressure Vessels
particle examination of steel forgings using alternating current
A788/A788M Specification for Steel Forgings, General Re-
as the power source. The procedure will produce consistent
quirements
results upon which acceptance standards can be based. This
A963/A963M Specification for Deep Drawing Steel (DDS),
practice does not contain acceptance limits or recommended
3
Sheet, Carbon, Cold-Rolled (Withdrawn 2000)
quality levels.
2.2 Other Document:
1.2 Onlyalternating50–60cyclecurrentshallbeusedasthe
Practice No. SNT-TC-1A, Supplement B—Magnetic Par-
electric power source for any of the magnetizing methods.
4
ticle Method
1.3 When subsurface indications are sought in forgings,
then dc magnetization in accordance with Practice A275/
3. Terminology
A275M should be used.
3.1 Definitions:
1.4 The values stated in either inch-pound units or SI units
3.1.1 (ac) magnetic particle method of examination, n—a
are to be regarded separately as standard. Within the text, the
method for detecting discontinuities on the surface in suitably
SI units are shown in brackets. The values stated in each
magnetized materials, which employs finely divided magnetic
system are not exact equivalents; therefore each system shall
particles that tend to congregate in regions of leakage fields.
be used independently of the other. Combining values from the
3.1.2 indication, n—the visual magnetic particle buildup
two systems may result in nonconformance with the specifi-
resulting from leakage fields in the magnetic field.
cation. Unless the order specifies the applicable “M” specifi-
3.1.3 linear indication, n—an indication in which the length
cation designation [SI units], the inch-pound units shall be
is at least three times the width. The minimum length of
used.
1
indications to be considered linear shall be ⁄16 in. [1.5 mm].
1.5 This standard does not purport to address all of the
3.1.4 magnetic flux, n—the product of the magnetic induc-
safety concerns, if any, associated with its use. It is the
tion and the area of a surface (or cross section) when the
responsibility of the user of this standard to establish appro-
magnetic induction is uniformly distributed and normal to the
priate safety and health practices and determine the applica-
plane of the surface.
bility of regulatory limitations prior to use.
3.1.4.1 Discussion—The concept that the magnetic field is
flowing along the lines of force suggests that these lines are
2. Referenced Documents
therefore “flux” lines, and they are called magnetic flux.
2
2.1 ASTM Standards:
3.1.5 nonrelevant indications, n—indications produced by
A275/A275M Practice for Magnetic Particle Examination of
leakagefieldswheretheconditionscausingthemarepresentby
Steel Forgings
accident or part design, or other features of the part having no
relation to the damaging flaws being sought.
3.1.5.1 Discussion—This term signifies that such an indica-
1
This practice is under the jurisdiction of ASTM Committee A01 on Steel,
tion has no relation to the discontinuities that might constitute
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
defects.
Current edition approved May 1, 2015. Published May 2015. Originally
approved in 1996. Last previous edition approved in 2012 as A966/A966M – 08
(2012). DOI: 10.1520/A0966_A0966M-15.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM www.astm.org.
4
Standards volume information, refer to the standard’s Document Summary page on AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
the ASTM website. 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.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
1
---------------------- Page: 1 ----------------------
A966/A966M − 15
4. Basis of Application 9. Magnetic Particles
9.1 The inspection medium shall consist of finely divid
...
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: A966/A966M − 08 (Reapproved 2012) A966/A966M − 15
Standard Practice for
Magnetic Particle Examination of Steel Forgings Using
1
Alternating Current
This standard is issued under the fixed designation A966/A966M; 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 practice covers a procedure for the magnetic particle examination of steel forgings using alternating current as the
power source. The procedure will produce consistent results upon which acceptance standards can be based. This practice does not
contain acceptance limits or recommended quality levels.
1.2 Only alternating 50–60 cycle current shall be used as the electric power source for any of the magnetizing methods.
1.3 When subsurface indications are sought in forgings, then dc magnetization in accordance with Practice A275/A275M should
be used.
1.4 The values stated in either inch-pound units or SI units are to be regarded separately 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 shall be used
independently of the other. Combining values from the two systems may result in nonconformance with the specification. Unless
the order specifies the applicable “M” specification designation [SI units], the inch-pound units shall be used.
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
2.1 ASTM Standards:
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A508/A508M Specification for Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels
A788/A788M Specification for Steel Forgings, General Requirements
3
A963/A963M Specification for Deep Drawing Steel (DDS), Sheet, Carbon, Cold-Rolled (Withdrawn 2000)
2.2 Other Document:
4
Practice No. SNT-TC-1A, Supplement B—Magnetic Particle Method
3. Terminology
3.1 Definitions:
3.1.1 (ac) magnetic particle method of examination, n—a method for detecting discontinuities on the surface in suitably
magnetized materials, which employs finely divided magnetic particles that tend to congregate in regions of leakage fields.
3.1.2 indication, n—the visual magnetic particle buildup resulting from leakage fields in the magnetic field.
3.1.3 linear indication, n—an indication in which the length is at least three times the width. The minimum length of indications
1
to be considered linear shall be ⁄16 in. [1.5 mm].
1
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, 2012May 1, 2015. Published May 2012May 2015. Originally approved in 1996. Last previous edition approved in 20082012 as
A966/A966M – 08.A966/A966M – 08 (2012). DOI: 10.1520/A0966_A0966M-08R12.10.1520/A0966_A0966M-15.
2
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 the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
4
Available from American Society for NonDestructive Testing, 1711 Arlingate Lane, Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus,
OH 43228-0518.43228-0518, http://www.asnt.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
1
---------------------- Page: 1 ----------------------
A966/A966M − 15
3.1.4 magnetic flux, n—the product of the magnetic induction and the area of a surface (or cross section) when the magnetic
induction is uniformly distributed and normal to the plane of the surface.
3.1.4.1 Discussion—
The concept that the magnetic field is flowing along the lines of force suggests that these lines are therefore “flux” lines, and they
are called magnetic flux.
3.1.5 no
...
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