ASTM E751/E751M-12

Standard Practice for Acoustic Emission Monitoring During Resistance Spot-Welding

SIGNIFICANCE AND USE
The AE produced during the production of a spot-weld can be related to weld quality parameters such as the strength and size of the nugget, the amount of expulsion, and the amount of cracking. Therefore, in-process AE monitoring can be used both as an examination method, and as a means for providing feedback control.
SCOPE
1.1 This practice describes procedures for the measurement, processing, and interpretation of the acoustic emission (AE) response associated with selected stages of the resistance spot-welding process.
1.2 This practice also provides guidelines for feedback control by utilizing the measured AE response signals during the spot-welding process.
1.3 Units—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 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.

General Information

• Status: Historical
• Publication Date: 14-Jun-2012
• ICS: 17.140.20 - Noise emitted by machines and equipment
• ICS: 25.160.10 - Welding processes
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.04 - Acoustic Emission Method

Relations

• Replaces: ASTM E751-07 - Standard Practice for Acoustic Emission Monitoring During Resistance Spot-Welding
• Effective Date: 15-Jun-2012

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E751/E751M − 12
Standard Practice for
Acoustic Emission Monitoring During Resistance Spot-
1
Welding
This standard is issued under the fixed designation E751/E751M; 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.
4
1. Scope* 2.3 AIA Standard:
NAS-410 Certification and Qualification of Nondestructive
1.1 This practice describes procedures for the measurement,
Personnel (Quality Assurance Committee)
processing, and interpretation of the acoustic emission (AE)
response associated with selected stages of the resistance
3. Terminology
spot-welding process.
3.1 Definitions—For definitions of terms relating to acoustic
1.2 This practice also provides guidelines for feedback
emission testing, see Section B of Terminology E1316.
control by utilizing the measured AE response signals during
the spot-welding process.
4. Summary of Practice
1.3 Units—The values stated in either SI units or inch-
4.1 The resistance spot-welding process consists of several
pound units are to be regarded separately as standard. The
stages. These are the set-down of the electrodes, squeeze,
values stated in each system may not be exact equivalents;
current flow, forging, hold time, and lift-off. Various types of
therefore, each system shall be used independently of the other.
acoustic emission signals are produced during each of these
Combining values from the two systems may result in non-
stages. Often, these signals can be identified with respect to the
conformance with the standard.
nature of their source. The individual signal elements may be
1.4 This standard does not purport to address all of the
greatly different, or totally absent, in various materials,
safety concerns, if any, associated with its use. It is the
thicknesses, and so forth. Fig. 1 is a schematic representation
responsibility of the user of this standard to establish appro-
showing typical signal elements which may be present in the
priate safety and health practices and determine the applica-
AE signature from a given spot-weld.
bility of regulatory limitations prior to use.
4.2 Most of the depictedAE signal features can be related to
2. Referenced Documents factors of weld quality. TheAE occurring during set-down and
squeeze can often be related to the condition of the electrodes
2
2.1 ASTM Standards:
and the surface of the parts. The large, often brief, signal at
E543 Specification for Agencies Performing Nondestructive
current initiation can be related to the initial resistance, and the
Testing
cleanliness of the part. For example, burning through of certain
E1316 Terminology for Nondestructive Examinations
oxide layers contributes to the acoustic emission response
3
2.2 ASNT Standards:
during this time.
SNT-TC-1A Recommended Practice for Nondestructive
4.2.1 During current flow, plastic deformation, nugget
Testing Personnel Qualification and Certification
expansion, friction, melting, and expulsions produce AE sig-
ANSI/ASNT CP-189 Standard for Qualification and Certifi-
nals. The signals caused by expulsion (spitting or flashing, or
cation of Nondestructive Testing Personnel
both) generally have large amplitudes and can be distinguished
from the rest of the acoustic emission associated with nugget
formation. Fig. 2 shows typical AE response signals during
1
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.04 on current flow for both d-c and a-c welding.
Acoustic Emission Method.
4.2.2 Following termination of the welding current, some
Current edition approved June 15, 2012. Published July 2012. Originally
materials exhibit appreciable AE noise during solidification
approved in 1980. Last previous edition approved in 2007 as E751 - 07. DOI:
which can be related to nugget size and inclusions. As the
10.1520/E0751-12.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
4
the ASTM website. Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
3
AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
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
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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:E751–07 Designation:E751/E751M–12
Standard Practice for
Acoustic Emission Monitoring During Resistance Spot-
1
Welding
This standard is issued under the fixed designation E751/E751M; 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 describes procedures for the measurement, processing, and interpretation of the acoustic emission (AE)
response associated with selected stages of the resistance spot-welding process.
1.2 This practice also provides guidelines for feedback control by utilizing the measured AE response signals during the
spot-welding process.
1.3
1.3 Units—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 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:
E543 Specification for Agencies Performing Nondestructive Testing
E1316 Terminology for Nondestructive Examinations
3
2.2 ASNT Standards:
SNT-TC-1A Recommended Practice for Nondestructive Testing Personnel Qualification and Certification
ANSI/ASNT CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
4
2.3 AIA Standard:
NAS-410 Certification and Qualification of Nondestructive Personnel (Quality Assurance Committee)
3. Terminology
3.1 Definitions—For definitions of terms relating to acoustic emission testing, see Section B of Terminology E1316.
4. Significance and Use
4.1The AE produced during the production of a spot-weld can be related to weld quality parameters such as the strength and
size of the nugget, the amount of expulsion, and the amount of cracking. Therefore, in-process AE monitoring can be used both
as an examination method, and as a means for providing feedback control. Summary of Practice
4.1 The resistance spot-welding process consists of several stages. These are the set-down of the electrodes, squeeze, current
flow, forging, hold time, and lift-off. Various types of acoustic emission signals are produced during each of these stages. Often,
these signals can be identified with respect to the nature of their source. The individual signal elements may be greatly different,
or totally absent, in various materials, thicknesses, and so forth. Fig. 1 is a schematic representation showing typical signal
elements which may be present in the AE signature from a given spot-weld.
4.2 Most of the depicted AE signal features can be related to factors of weld quality. The AE occurring during set-down and
squeeze can often be related to the condition of the electrodes and the surface of the parts. The large, often brief, signal at current
1
This practice is under the jurisdiction ofASTM Committee E07 on NondestructiveTesting and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission
Method.
Current edition approved Feb.June 15, 2007.2012. Published March 2007.July 2012. Originally approved in 1980. Last previous edition approved in 20012007 as
E751 - 017. DOI: 10.1520/E0751-07.10.1520/E0751-12.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
4
Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.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.
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E751/E751M–12
FIG. 1 Typical AE Response Signals During Resistance Spot W
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