ASTM F2328-17(2022)
(Test Method)Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts
Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts
SIGNIFICANCE AND USE
4.1 Decarburization and carburization are two surface conditions created, either intentionally or unintentionally, as with a pre-existing condition created during the rod rolling process, the rod/wire annealing process, or while heat treating threaded steel products. Too much of either will adversely affect the safety and performance of the threaded product. Therefore, limits have been established for three different product groups: the harder and greater the tensile strength of the product, the more susceptible to failure the product becomes if these limits are exceeded.
4.2 When testing to a particular product specification that lists the dimensions and microindentation data to be used, that data shall take precedence over the tables in this test method.
4.3 There are only two viable methods available to detect these deficiencies, either by the visual method or the microindentation method. Both methods are used for routine inspections when evaluations are conducted at a single location on the product sample.
4.3.1 Because an evaluation at a specific location may not be representative of the whole part, the referee method employs the microindentation method taken as an average of evaluations conducted on four adjacent threads. This procedure significantly reduces the random test variables when compared to testing on a single thread.
4.4 Specifying this test method does not specify or imply that testing shall be for either decarburization or carburization alone or for both conditions. When either test method is performed, both conditions will be apparent and shall be reported. For example, if an order is placed to test for decarburization and none is found, but the presence of carburization is detected, it shall be reported on the test report that carburization was found.
SCOPE
1.1 This test method covers procedures for measuring, classifying, and determining the presence of decarburization and carburization in the threaded section of hardened and tempered inch series steel bolts, screws, studs, nuts, and similar parts which have been heated to facilitate fabrication or to modify their mechanical properties. This test method is not intended to address products which are intentionally carburized to achieve specific results.
1.2 Two routine methods are described for measuring the limits of and determining the presence of decarburization or carburization—the optical method and the microindentation method 1. Either method is appropriate for routine examinations. The microindentation method 2 shall be considered the referee method.
1.3 For the purpose of these tests, there are four classes of hardened and tempered steel products for which specific measurements must be made with respect to their physical properties.
1.4 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.
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, health, and environmental 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.
General Information
- Status
- Published
- Publication Date
- 31-Jul-2022
- Technical Committee
- F16 - Fasteners
- Drafting Committee
- F16.01 - Test Methods
Relations
- Effective Date
- 01-Nov-2023
- Effective Date
- 01-Jun-2017
- Effective Date
- 01-Aug-2016
- Effective Date
- 01-Mar-2015
- Effective Date
- 01-Feb-2015
- Effective Date
- 01-Sep-2014
- Effective Date
- 01-Feb-2014
- Effective Date
- 01-Dec-2012
- Effective Date
- 01-Jun-2012
- Effective Date
- 01-Nov-2011
- Effective Date
- 01-Nov-2011
- Effective Date
- 01-May-2011
- Effective Date
- 01-Dec-2010
- Effective Date
- 01-May-2010
- Effective Date
- 01-May-2010
Overview
ASTM F2328-17(2022), "Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts," establishes procedures for measuring and classifying decarburization and carburization in the threaded sections of steel fasteners. Developed by ASTM International, this test method is essential for maintaining the safety, mechanical integrity, and performance of high-strength threaded steel products that have undergone heat treatment to alter their mechanical properties.
The standard is widely applied in the manufacturing and quality control of mechanical fasteners, including bolts, screws, studs, and nuts. It offers two primary evaluation methods: the optical method and the microindentation hardness method, with the latter serving as the referee test.
Key Topics
- Decarburization: Loss of carbon from the surface layer of steel fasteners, often resulting from heat treatment processes, which can affect mechanical strength and lead to premature failure.
- Carburization: Increase in surface carbon content, which can also negatively impact fastener reliability and performance.
- Testing Methods:
- Optical Method: Uses metallographic examination to assess surface conditions after etching.
- Microindentation Hardness Method: Measures variations in surface and subsurface hardness using Knoop or Vickers indenters.
- Product Classification: Divides fasteners into four classes based on physical properties (such as tensile strength and hardness), each requiring specific measurement protocols.
- Significance: Too much decarburization or carburization can seriously impair the safety of fasteners, especially those with higher tensile strengths.
- Reporting: The standard requires documentation of both decarburization and carburization, even if only one condition was originally specified for testing.
Applications
ASTM F2328-17(2022) is a crucial standard in several industries reliant on the integrity of steel fasteners. Its typical applications include:
- Automotive Manufacturing: Ensures bolts and screws used in critical assemblies meet strength and durability requirements.
- Construction and Infrastructure: Helps prevent failures in structural fasteners, especially those subject to dynamic loads.
- Aerospace and Defense: Provides confidence in the reliability of fasteners under extreme conditions.
- Quality Assurance: Enables routine inspection and conformance for manufacturers of threaded steel products, ensuring compliance with regulatory and customer specifications.
- Failure Analysis: Assists engineers in diagnosing fastener failures related to surface carbon content changes, helping to identify root causes and prevent recurrence.
- Supply Chain Compliance: Supports suppliers and purchasers in verifying the metallurgical quality of fasteners before acceptance or deployment.
Related Standards
ASTM F2328-17(2022) aligns with several industry-recognized standards and guides, including:
- ASTM E3: Guide for Preparation of Metallographic Specimens.
- ASTM E384: Test Method for Microindentation Hardness of Materials.
- ASTM F1789: Terminology for F16 Mechanical Fasteners.
- International Standards: Developed following the World Trade Organization (WTO) Technical Barriers to Trade (TBT) Committee principles, ensuring international relevance and acceptability.
Practical Value
Adhering to ASTM F2328-17(2022) helps manufacturers, suppliers, and customers maintain product quality, reduce safety risks, and comply with both domestic and international regulatory requirements. By providing clear procedures for detecting and quantifying decarburization and carburization in threaded steel fasteners, this standard is essential for anyone involved in the quality assurance or manufacturing of high-strength steel components.
Keywords: decarburization, carburization, threaded steel fasteners, ASTM F2328, microindentation hardness, optical method, mechanical fasteners, steel bolts, screws, tensile strength, heat treatment, quality assurance, metallography.
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ASTM F2328-17(2022) - Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts
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Frequently Asked Questions
ASTM F2328-17(2022) is a standard published by ASTM International. Its full title is "Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts". This standard covers: SIGNIFICANCE AND USE 4.1 Decarburization and carburization are two surface conditions created, either intentionally or unintentionally, as with a pre-existing condition created during the rod rolling process, the rod/wire annealing process, or while heat treating threaded steel products. Too much of either will adversely affect the safety and performance of the threaded product. Therefore, limits have been established for three different product groups: the harder and greater the tensile strength of the product, the more susceptible to failure the product becomes if these limits are exceeded. 4.2 When testing to a particular product specification that lists the dimensions and microindentation data to be used, that data shall take precedence over the tables in this test method. 4.3 There are only two viable methods available to detect these deficiencies, either by the visual method or the microindentation method. Both methods are used for routine inspections when evaluations are conducted at a single location on the product sample. 4.3.1 Because an evaluation at a specific location may not be representative of the whole part, the referee method employs the microindentation method taken as an average of evaluations conducted on four adjacent threads. This procedure significantly reduces the random test variables when compared to testing on a single thread. 4.4 Specifying this test method does not specify or imply that testing shall be for either decarburization or carburization alone or for both conditions. When either test method is performed, both conditions will be apparent and shall be reported. For example, if an order is placed to test for decarburization and none is found, but the presence of carburization is detected, it shall be reported on the test report that carburization was found. SCOPE 1.1 This test method covers procedures for measuring, classifying, and determining the presence of decarburization and carburization in the threaded section of hardened and tempered inch series steel bolts, screws, studs, nuts, and similar parts which have been heated to facilitate fabrication or to modify their mechanical properties. This test method is not intended to address products which are intentionally carburized to achieve specific results. 1.2 Two routine methods are described for measuring the limits of and determining the presence of decarburization or carburization—the optical method and the microindentation method 1. Either method is appropriate for routine examinations. The microindentation method 2 shall be considered the referee method. 1.3 For the purpose of these tests, there are four classes of hardened and tempered steel products for which specific measurements must be made with respect to their physical properties. 1.4 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard. 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, health, and environmental 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.
SIGNIFICANCE AND USE 4.1 Decarburization and carburization are two surface conditions created, either intentionally or unintentionally, as with a pre-existing condition created during the rod rolling process, the rod/wire annealing process, or while heat treating threaded steel products. Too much of either will adversely affect the safety and performance of the threaded product. Therefore, limits have been established for three different product groups: the harder and greater the tensile strength of the product, the more susceptible to failure the product becomes if these limits are exceeded. 4.2 When testing to a particular product specification that lists the dimensions and microindentation data to be used, that data shall take precedence over the tables in this test method. 4.3 There are only two viable methods available to detect these deficiencies, either by the visual method or the microindentation method. Both methods are used for routine inspections when evaluations are conducted at a single location on the product sample. 4.3.1 Because an evaluation at a specific location may not be representative of the whole part, the referee method employs the microindentation method taken as an average of evaluations conducted on four adjacent threads. This procedure significantly reduces the random test variables when compared to testing on a single thread. 4.4 Specifying this test method does not specify or imply that testing shall be for either decarburization or carburization alone or for both conditions. When either test method is performed, both conditions will be apparent and shall be reported. For example, if an order is placed to test for decarburization and none is found, but the presence of carburization is detected, it shall be reported on the test report that carburization was found. SCOPE 1.1 This test method covers procedures for measuring, classifying, and determining the presence of decarburization and carburization in the threaded section of hardened and tempered inch series steel bolts, screws, studs, nuts, and similar parts which have been heated to facilitate fabrication or to modify their mechanical properties. This test method is not intended to address products which are intentionally carburized to achieve specific results. 1.2 Two routine methods are described for measuring the limits of and determining the presence of decarburization or carburization—the optical method and the microindentation method 1. Either method is appropriate for routine examinations. The microindentation method 2 shall be considered the referee method. 1.3 For the purpose of these tests, there are four classes of hardened and tempered steel products for which specific measurements must be made with respect to their physical properties. 1.4 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard. 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, health, and environmental 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.
ASTM F2328-17(2022) is classified under the following ICS (International Classification for Standards) categories: 21.060.01 - Fasteners in general; 77.140.20 - Stainless steels. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM F2328-17(2022) has the following relationships with other standards: It is inter standard links to ASTM F1789-23, ASTM F1789-17, ASTM F1789-16, ASTM F1789-15a, ASTM F1789-15, ASTM F1789-14a, ASTM F1789-14, ASTM F1789-12a, ASTM F1789-12, ASTM F1789-11b, ASTM F1789-11a, ASTM F1789-11, ASTM F1789-10b, ASTM F1789-10ae1, ASTM F1789-10a. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM F2328-17(2022) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
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.
Designation: F2328 − 17 (Reapproved 2022)
Standard Test Method for
Determining Decarburization and Carburization in Hardened
and Tempered Threaded Steel Bolts, Screws, Studs, and
Nuts
This standard is issued under the fixed designation F2328; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers procedures for measuring,
E3Guide for Preparation of Metallographic Specimens
classifying, and determining the presence of decarburization
E384Test Method for Microindentation Hardness of Mate-
and carburization in the threaded section of hardened and
rials
temperedinchseriessteelbolts,screws,studs,nuts,andsimilar
F1789Terminology for F16 Mechanical Fasteners
parts which have been heated to facilitate fabrication or to
modify their mechanical properties. This test method is not
3. Terminology
intendedtoaddressproductswhichareintentionallycarburized
to achieve specific results.
3.1 Definitions:
3.1.1 carburization—process or result of increasing the
1.2 Two routine methods are described for measuring the
carbon content of the surface layers of the steel fastener
limits of and determining the presence of decarburization or
product.
carburization—the optical method and the microindentation
method 1. Either method is appropriate for routine examina- 3.1.2 decarburization—in accordance with Terminology
F1789,isalossofcarbonfromthesurfacelayerofthefastener,
tions. The microindentation method 2 shall be considered the
normally associated with heat treatment.
referee method.
3.1.3 gross decarburization—also known as complete
1.3 For the purpose of these tests, there are four classes of
decarburization, is characterized by a sufficient carbon loss to
hardened and tempered steel products for which specific
show only clearly defined ferrite grains.
measurements must be made with respect to their physical
properties. 3.1.4 partial decarburization—characterized as a loss of
carbon sufficient to cause a lighter shade of tempered marten-
1.4 Thevaluesstatedininch-poundunitsaretoberegarded
site than that of the immediately adjacent base metal, but as
asstandard.Nootherunitsofmeasurementareincludedinthis
being of insufficient carbon loss to show clearly defined ferrite
standard.
grains.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
4.1 Decarburization and carburization are two surface con-
priate safety, health, and environmental practices and deter-
ditions created, either intentionally or unintentionally, as with
mine the applicability of regulatory limitations prior to use.
a pre-existing condition created during the rod rolling process,
1.6 This international standard was developed in accor-
the rod/wire annealing process, or while heat treating threaded
dance with internationally recognized principles on standard-
steel products. Too much of either will adversely affect the
ization established in the Decision on Principles for the
safety and performance of the threaded product. Therefore,
Development of International Standards, Guides and Recom-
limits have been established for three different product groups:
mendations issued by the World Trade Organization Technical
the harder and greater the tensile strength of the product, the
Barriers to Trade (TBT) Committee.
more susceptible to failure the product becomes if these limits
are exceeded.
This test method is under the jurisdiction of ASTM Committee F16 on
Fasteners and is the direct responsibility of Subcommittee F16.01 on Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2022. Published December 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2004. Last previous edition approved in 2017 as F2328–17. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F2328-17R22. the ASTM website.
*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
F2328 − 17 (2022)
4.2 When testing to a particular product specification that of any light-etching band of martensite defines the depth of
lists the dimensions and microindentation data to be used, that decarburization. Compare the image with Fig. 1 for the
data shall take precedence over the tables in this test method. maximum limits for G by taking a measurement on a line
perpendicular to the flank of the thread midway between the
4.3 There are only two viable methods available to detect
thread crest and root (pitch diameter).
these deficiencies, either by the visual method or the microin-
dentation method. Both methods are used for routine inspec- 7.2 Interpretation of Results:
tionswhenevaluationsareconductedatasinglelocationonthe 7.2.1 Allowablelimitsforpartialdecarburizationshallbein
product sample. accordancewith3.1.4andFig.1,andthemeasuredvaluesshall
4.3.1 Because an evaluation at a specific location may not be in accordance with Table 2, when measured in accordance
be representative of the whole part, the referee method em- with the illustrations in Figs. 2 and 3.
ploys the microindentation method taken as an average of 7.2.2 Allowablelimitsforgrossdecarburization(G)shallbe
evaluationsconductedonfouradjacentthreads.Thisprocedure inaccordancewith3.1.3andthemeasuredvaluesasdefinedin
significantlyreducestherandomtestvariableswhencompared Table 1. The optical method is the only valid method for
to testing on a single thread. evaluating the depth of gross decarburization. Gross decarbur-
ization is prohibited in Class 3 products.
4.4 Specifying this test method does not specify or imply
7.2.3 Carburization is identified when the tempered marten-
that testing shall be for either decarburization or carburization
siteisadarkershadethantheimmediatelyadjacentbasemetal.
alone or for both conditions. When either test method is
If visible evidence of surface carburization is present on the
performed, both conditions will be apparent and shall be
surfacezone,themicroindentationmethod,inaccordancewith
reported. For example, if an order is placed to test for
Section 8, shall be used.
decarburization and none is found, but the presence of carbur-
7.2.4 The optical method may not be appropriate for speci-
ization is detected, it shall be reported on the test report that
menswithcertaincoatings,suchaszinc,wherethecoatingcan
carburization was found.
affecttheetchingprocessanddistorttheappearanceofthebase
material microstructure.These coatings shall be removed prior
5. Class of Decarburization
to mounting if the coating prevents proper etching. Care must
5.1 Class Determination—These measurements by Class
also be exercised to not alter the surface condition of the
arepredicatedupontheirrelationshipbetweentheheight(H)of
substrate during the coating removal process.
the external thread at its maximum boundary, disregarding any
7.2.5 If the results of the optical method indicate a possible
surface coating, and N, which is the minimum thread height in
nonconformanceinthemeasurementofpartialdecarburization
the non-decarburized zone (see Figs. 1-3). The dimensions for
or carburization, or are otherwise inconclusive, the microin-
N and H are listed in Table 2 for each Class. Dimension G
dentation method (Section 8) shall be performed after the
(Table 1 and Fig. 1) represents the maximum depth of gross or
specimens are repolished.
complete decarburization.
NOTE1—Refertotheproductstandardforspecificrequirements.When
8. Evaluation by the Microi
...




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