ASTM F606/F606M-21

Standard Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets

ABSTRACT
These test methods establishes the standard procedures for conducting tests to determine the mechanical properties of externally and internally threaded fasteners, washers and direct tension indicators, and rivets. For externally threaded fasteners, the mechanical tests describe the procedures for determining the following properties: product hardness; proof load by length measurement (Method 1), yield strength (Method 2), yield strength of austenitic stainless steel and nonferrous materials (Method 2A), and uniform hardness (Method 3); axial tension of full size products such as fasteners and studs; wedge tension of full size products such as fasteners and studs; tension of machined test specimens including yield point (by drop of the beam or halt of the pointer, autographic diagram, and total extension under load methods), yield strength (by offset, and extension under load methods), tensile strength, elongation, and reduction of area; and total extension at fracture. As for internally threaded fasteners including nonheat- and heat-treated nuts, tests are provided for the determination of product hardness, proof load, and cone proof load. Test for determining the surface and core hardnesses are, conversely, described for direct tension indicators, and through-hardened, carburized, stainless steel, and nonferrous washers. And finally, product hardness testing is described for rivets. The test method for determining embrittlement of metallic coated externally threaded fasteners is detailed as well.
SCOPE
1.1 These test methods cover establishment of procedures for conducting tests to determine the mechanical properties of externally and internally threaded fasteners, washers, direct tension indicators, and rivets.  
1.2 Property requirements and the applicable tests for their determination are specified in individual product standards. In those instances where the testing requirements are unique or at variance with these standard procedures, the product standard shall specify the controlling testing requirements. In the absence of any specified test requirement(s), these test methods shall apply.  
1.3 These test methods describe mechanical tests for determining the following properties:    
Section    
For Externally Threaded Fasteners:  
3  
Product Hardness  
3.1  
Proof Load  
3.2.1  
Method 1, Length Measurement  
3.2.3  
Method 2, Yield Strength  
3.2.4  
Method 3, Uniform Hardness  
3.2.5  
Axial Tension Testing of Full-Size Product  
3.4  
Wedge Tension Testing of Full-Size Product  
3.5  
Tension Testing of Machined Test Specimens  
3.6  
Total Extension at Fracture Test
Single Sheer Test  
3.7
3.8  
For Internally Threaded Fasteners:  
4  
Product Hardness  
4.1  
Proof Load Test  
4.2  
Cone Proof Load Test  
4.3  
For Washers and Direct Tension Indicators:  
5  
Product Hardness-General Requirements  
5.1  
Through Hardened Washers  
5.2  
Carburized Washers  
5.3  
Stainless Steel and Nonferrous Washers  
5.4  
Direct Tension Indicators  
5.5  
Compression Load  
5.6  
For Rivets:  
6  
Product Hardness  
6.1  
Test for Embrittlement of Metallic-Coated Externally Threaded Fasteners  
7  
Test Method for Determining Decarburization and Carburization  
8  
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
Note 1: The values are stated in inch-pound for inch fasteners and SI metric units for metric fasteners.  
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 approp...

General Information

• Status: Published
• Publication Date: 31-May-2021
• ICS: 21.060.01 - Fasteners in general
• Technical Committee: F16 - Fasteners
• Drafting Committee: F16.01 - Test Methods

Relations

• Replaces: ASTM F606M-14 - Standard Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, and Rivets (Metric) (Withdrawn 2015)
• Effective Date: 08-Apr-2015
• Refers: ASTM E8/E8M-24 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM A394-08(2024) - Standard Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
• Effective Date: 01-Jan-2024
• Refers: ASTM F1624-12(2018) - Standard Test Method for Measurement of Hydrogen Embrittlement Threshold in Steel by the Incremental Step Loading Technique
• Effective Date: 01-Nov-2018
• Refers: ASTM F436/F436M-18a - Standard Specification for Hardened Steel Washers Inch and Metric Dimensions
• Effective Date: 01-Sep-2018
• Refers: ASTM E18-18 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Jul-2018
• Refers: ASTM F436/F436M-18 - Standard Specification for Hardened Steel Washers Inch and Metric Dimensions
• Effective Date: 01-Jun-2018
• Refers: ASTM E18-17 - Standard Test Methods for Rockwell Hardness of Metallic Materials
• Effective Date: 01-Jul-2017
• Refers: ASTM F436/F436M-16 - Standard Specification for Hardened Steel Washers Inch and Metric Dimensions
• Effective Date: 01-Sep-2016
• Refers: ASTM E8/E8M-16 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 15-Jul-2016
• Refers: ASTM F959-15 - Standard Specification for Compressible-Washer-Type Direct Tension Indicators for Use with Structural Fasteners
• Effective Date: 01-May-2015
• Refers: ASTM E8/E8M-15 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Feb-2015
• Refers: ASTM F2328-14 - Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts
• Effective Date: 01-Aug-2014
• Refers: ASTM F2328M-14 - Standard Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts, Screws, Studs, and Nuts (Metric)
• Effective Date: 01-Aug-2014
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014

Overview

ASTM F606/F606M-21 is a comprehensive standard developed by ASTM International that specifies test methods for determining the mechanical properties of fasteners and related components. This standard applies to externally and internally threaded fasteners, washers, direct tension indicators, and rivets. It outlines standardized procedures for mechanical testing such as hardness, proof load, yield strength, tension, and more, ensuring consistency and reliability in fastener performance assessments. The use of both SI metric and inch-pound units allows for global adoption and enhances its relevance in diverse industrial settings.

Key Topics

• Mechanical Properties Testing: Outlines methods to evaluate product hardness, proof load, yield strength, and tensile strength for various types of fasteners.
• Axial and Wedge Tension Testing: Provides procedures for axial tension and wedge tension tests, crucial for assessing the strength and ductility of fasteners and studs.
• Product-Specific Tests:
  • Externally Threaded Fasteners: Includes hardness, proof load (length measurement, yield strength, uniform hardness), tension, and fracture tests.
  • Internally Threaded Fasteners: Covers product hardness, proof load, and cone proof load testing.
  • Washers and Direct Tension Indicators: Details tests for through-hardened, carburized, stainless steel, and nonferrous washers, as well as compression load for direct tension indicators.
  • Rivets: Specifies methods to determine product hardness.
• Specialized Testing: Describes methods for evaluating embrittlement in metallic-coated fasteners and processes for decarburization and carburization assessment.
• Dual Units of Measurement: Clearly stipulates that SI and inch-pound units must be used independently, never combined, ensuring accuracy and consistency.

Applications

ASTM F606/F606M-21 is widely used across industries where fastener performance is critical, including:

• Construction and Infrastructure: Ensures that bolts, nuts, and washers used in structural applications meet required safety and quality standards.
• Manufacturing and Assembly: Provides a basis for quality control testing in factories producing fasteners for automotive, aerospace, and machinery applications.
• Product Development: Supports engineers in verifying fastener specifications during the design and prototyping stages for robust product performance.
• Quality Assurance and Compliance: Assists manufacturers and suppliers in meeting procurement requirements and regulatory standards, particularly in sectors governed by strict mechanical property criteria.
• Testing Laboratories: Offers standardized methodologies that promote accuracy and repeatability in laboratory test reporting.

By adhering to the methods in ASTM F606/F606M-21, organizations can:

• Ensure uniformity and comparability in mechanical property test results.
• Reduce the risk of fastener failure in service.
• Meet international procurement and regulatory requirements.
• Safeguard end-user safety through reliable product performance.

Related Standards

To fully implement ASTM F606/F606M-21 or for more detailed procedures, the following standards are often referenced or used in conjunction:

• ASTM E4: Practices for Force Verification of Testing Machines
• ASTM E8/E8M: Test Methods for Tension Testing of Metallic Materials
• ASTM E10: Brinell Hardness Testing of Metallic Materials
• ASTM E18: Rockwell Hardness Testing of Metallic Materials
• ASTM E92/E384: Test Methods for Microindentation Hardness
• ASTM F436/F436M: Specification for Hardened Steel Washers
• ASTM F959: Specification for Direct Tension Indicators
• ASTM F1624: Measurement of Hydrogen Embrittlement Threshold in Steel
• ASTM F2328/F2328M: Determining Decarburization and Carburization in Steel Fasteners

Adopting ASTM F606/F606M-21 and related standards ensures that the mechanical properties of fasteners and components are accurately measured, providing critical quality assurance for a broad range of industrial applications.

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: F606/F606M − 21
Standard Test Methods for
Determining the Mechanical Properties of Externally and
Internally Threaded Fasteners, Washers, Direct Tension
Indicators, and Rivets
This standard is issued under the fixed designation F606/F606M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
Product Hardness 6.1
Test for Embrittlement of Metallic-Coated Externally Threaded 7
1.1 These test methods cover establishment of procedures
Fasteners
for conducting tests to determine the mechanical properties of Test Method for Determining Decarburization and Carburization 8
externally and internally threaded fasteners, washers, direct
1.4 The values stated in either SI units or inch-pound units
tension indicators, and rivets.
are to be regarded separately as standard. The values stated in
each system are not necessarily exact equivalents; therefore, to
1.2 Property requirements and the applicable tests for their
ensure conformance with the standard, each system shall be
determination are specified in individual product standards. In
used independently of the other, and values from the two
those instances where the testing requirements are unique or at
systems shall not be combined.
variance with these standard procedures, the product standard
shall specify the controlling testing requirements. In the
NOTE 1—The values are stated in inch-pound for inch fasteners and SI
absenceofanyspecifiedtestrequirement(s),thesetestmethods
metric units for metric fasteners.
shall apply.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.3 These test methods describe mechanical tests for deter-
responsibility of the user of this standard to establish appro-
mining the following properties:
priate safety, health, and environmental practices and deter-
Section
For Externally Threaded Fasteners: 3 mine the applicability of regulatory limitations prior to use.
Product Hardness 3.1
1.6 This international standard was developed in accor-
Proof Load 3.2.1
dance with internationally recognized principles on standard-
Method 1, Length Measurement 3.2.3
Method 2, Yield Strength 3.2.4 ization established in the Decision on Principles for the
Method 3, Uniform Hardness 3.2.5
Development of International Standards, Guides and Recom-
Axial Tension Testing of Full-Size Product 3.4
mendations issued by the World Trade Organization Technical
Wedge Tension Testing of Full-Size Product 3.5
Tension Testing of Machined Test Specimens 3.6 Barriers to Trade (TBT) Committee.
Total Extension at Fracture Test 3.7
Single Sheer Test 3.8
2. Referenced Documents
For Internally Threaded Fasteners: 4
2.1 ASTM Standards:
Product Hardness 4.1
Proof Load Test 4.2
A394Specification for Steel Transmission Tower Bolts,
Cone Proof Load Test 4.3
Zinc-Coated and Bare
For Washers and Direct Tension Indicators: 5
E4Practices for Force Verification of Testing Machines
Product Hardness-General Requirements 5.1
Through Hardened Washers 5.2
E8/E8MTest Methods for Tension Testing of Metallic Ma-
Carburized Washers 5.3
terials
Stainless Steel and Nonferrous Washers 5.4
Direct Tension Indicators 5.5 E10Test Method for Brinell Hardness of Metallic Materials
Compression Load 5.6
E18Test Methods for Rockwell Hardness of Metallic Ma-
For Rivets: 6
terials
E83Practice for Verification and Classification of Exten-
someter Systems
These test methods are under the jurisdiction of ASTM Committee F16 on
Fasteners and are 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 June 1, 2021. Published June 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1979. Last previous edition approved in 2019 as F606/F606M–19. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/F0606_F0606M-21. 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
F606/F606M − 21
E92Test Methods for Vickers Hardness and Knoop Hard- The method used is at the option of the manufacturer, with
ness of Metallic Materials regards to the size and grade of the products.
E384Test Method for Microindentation Hardness of Mate-
3.1.1 Routine Test Locations—For testing the hardness of
rials
the finished product, the following test locations can be used:
F436/F436MSpecification for Hardened SteelWashers Inch
3.1.1.1 For hex and square head bolts; test shall be con-
and Metric Dimensions
ducted on the wrench flats, top of head, unthreaded shank, end
F959Specification for Compressible-Washer-Type Direct
of bolt or at the arbitration location.
Tension Indicators for Use With Structural Fasteners
3.1.1.2 Forstuds,productswithoutparallelwrenchflatsand
(Metric) F0959_F0959M
for head styles other than hex and square; tests shall be
F1624Test Method for Measurement of Hydrogen Em-
conducted on the unthreaded shank, end of the bolt or stud or
brittlement Threshold in Steel by the Incremental Step
at the arbitration location.
Loading Technique
3.1.1.3 Stress relieved products (3.1.1.1 and 3.1.1.2) are
F2328Test Method for Determining Decarburization and
measuredanywhereonthesurfaceorthroughthecrosssection.
Carburization in Hardened and Tempered Threaded Steel
Refer to the product specification for particular test location or
Bolts, Screws, Studs, and Nuts
use the arbitration location.
F2328MTest Method for Determining Decarburization and
3.1.1.4 The Rockwell Hardness Scale may be used for all
Carburization in Hardened and Tempered Threaded Steel
product diameters; however, the Brinell hardness is limited to
Bolts, Screws, Studs, and Nuts (Metric)
products over 1 ⁄2-in. or M36.
2.2 Military Standard:
3.1.2 Laboratory Inspection—Aminimum of three readings
MIL STD1312,Test 13 and Test 20
shall be taken on each sample of finished product.
3.1.3 Arbitration Test Location—Forpurposesofarbitration
3. Test Methods for Externally Threaded Fasteners
between the purchaser and seller over reported test results,
3.1 Product Hardness—Tests shall be conducted after the
hardness tests shall be conducted at the mid-radius (r/2) of a
removal of any surface oxide, decarburization, plating or other
transverse section through the threads taken at a distance of
coating.All readings shall be within the hardness values listed
approximately one diameter from the point end of the bolt or
in the product specification.The average of all readings on the
oneendofthestud.Fourreadingsshallbetakenfromthepoint
same part shall be considered as the product hardness. Test
end of the bolt or one end of the stud. Four readings shall be
results shall conform to the product specification for the lot
taken approximately 90° to one another on the same plane, if
representedbythetestspecimenstobeconsideredconforming.
product size permits. Smaller diameter products may also use
Test specimen preparation and hardness tests shall be con-
the opposite parallel surface area of the bolt head end as
ducted in accordance with Test Methods E18 for Rockwell
sectioned above (see Fig. 1). The use of Brinell hardness for
tests, Test Method E10 for Brinell tests, Test Method E92 for
arbitration testing is limited to product sizes greater than
Vickers tests, or Test Method E384 for Microhardness tests. 1
2 ⁄4-in. or M60.
3.2 Tension Tests—It is preferred that bolts and studs be
tested full size, and it is customary, when so testing, to specify
a minimum ultimate load (or stress) in pounds-force (or
DLA Document Services Building 4/D 700 Robbins Avenue Philadelphia, PA
19111-5094 http://quicksearch.dla.mil/
FIG. 1 Hardness Arbitration Test Location
F606/F606M − 21
pounds-forcepersquareinch.)forinchfastenersandorloadin fasteners and 3.0 mm/min for metric fasteners, as determined
newtons-force or megapascals MPa for metric fasteners. Sec- with a free-running cross head, axially load the fastener to the
tions3.2–3.5applywhentestingexternallythreadedfasteners
proof load value specified in the product specification. This
full size. Section 3.6 shall apply where the individual product load shall be maintained for a period of 10 s before releasing
specifications permit the use of machined specimens (see Test the load. Replace the fastener between the measuring anvils
Methods E8/E8M).
and rotate at least 360 degrees as before. The fastener shall be
stoppedatthepositionwherethelowestvalueisindicated.The
3.2.1 Proof Load—The proof-load test consists of stressing
measurement shall show no permanent elongation.Atolerance
the product with a specified load that the product must
of 60.0005 in. for inch fasteners and 6 0.013 mm for metric
withstand without measurable permanent set. Alternative tests
fasteners shall be allowed (for measurement error only) be-
for determining the ability of a fastener to pass the proof-load
tween the measurement made before loading and that made
test are the yield strength test and the uniform hardness test.
after loading. Variables such as straightness, thread alignment,
Either Method 1 (3.2.3), Method 2 (3.2.4), or Method 3 (3.2.5)
ormeasurementerrorcouldresultinapparentelongationofthe
may be used, but Method 1 shall be the arbitration method in
product when the specified proof load is initially applied. In
case of any dispute as to acceptance of the product (see Test
Methods E8/E8M). such cases, the product may be retested using a 3% greater
load, and shall be considered acceptable if there is no differ-
3.2.2 In both Methods 1 and 2, assemble the product in the
ence in the length measurement after this loading within a
fixture of the tension testing machine so that six complete
0.0005 in. for inch fasteners and 6 0.013 mm for metric
threads (except for heavy hex structural bolts, which shall be
fasteners, measurement tolerance as outlined.
based on four threads) are exposed between the grips. This is
obtained by freely running the nut or fixture to the thread 3.2.4 Method 2, Yield Strength—Assemble the product in
runout of the specimen and then unscrewing the specimen six the testing equipment as outlined in3.4.As the load is applied,
full turns. For continuous thread bolts, at least six full threads measure and record the total elongation of the product or any
shallbeexposedbetweenthefixtureends;however,forreferee part of it that includes the exposed threads to produce a
purposes, six full threads shall be exposed. load-elongation diagram. Determine the load or stress at an
offset equal to 0.2% of the length of bolt occupied by six full
3.2.3 Method1,LengthMeasurement—Toensureconsistent
threads as shown in Fig. 2 (except for heavy hex structural
and repetitive length measurements of the fastener, the
bolts, which shall be based on four threads) by the method
threaded end and top of the bolt head shall have conical
described in 3.6.3.1.
depressions made at the approximate axis or center line of the
fastener. In the event of a dispute over test results the test shall
3.2.4.1 Method 2A, Yield Strength for Austenitic Stainless
be conducted after the removal of all manufacturer or grade
Steel and Non-ferrous Materials—Assemble the product in the
markings, surface oxide, decarburization, plating, other
testing equipment as outlined in 3.4. As the load is applied,
coating, or a combination thereof, to achieve a clean, flat
measure and record the total elongation of the product in order
surface and the conical depressions shall be created using a
to produce a load elongation diagram. Determine the load or
lathe or some type of centering fixture. All debris shall be
stress at an offset equal to 0.2% strain based on the length of
removed from the conical depressions before measuring the
the bolt between the holders as shown in Fig. 2, which will be
part. When fasteners are too long to test in the available
subjecttoelongationunderloadbyusingthemethoddescribed
equipmentthefastenermaybecutto8inches 60.125forinch
in 3.6.3.1.
fastenersoralengthof200mm 63.0mmformetricfasteners
3.2.5 Method 3, Uniform Hardness—The fasteners shall be
and tested using Method 1. If there is a dispute over results
tested for hardness as described in 3.1, and in addition, the
whentestingthesamepartorlotofparts,bothfullsizeandcut
hardness shall also be determined in the core. The difference
fastener the cut fastener results shall be used to determine
between the mid-radius and core hardness shall be not more
acceptance. The measuring instrument shall have pointed
than 3 points on a Rockwell C Scale; and both readings must
anvils which mate with the center line depressions and be
be within product specification. This test is valid for fasteners
capable of measuring changes in length of 0.0001 in. for inch
up to and including 1 in. for inch fasteners and M24 diameter
fasteners and 0.0025 mm for metric fasteners. The instrument
for metric fasteners.
accuracy shall be within 0.0001 in. in any 0.001 in. range for
3.3 Bolts or Studs Too Short for Tension Testing—Product
inch parts and within 0.0025 mm accuracy within any 0.025
lengthslessthanthoseshowninTable1forproduct ⁄4through
mm range for metric parts. Place the fastener between the
⁄4 in. for inch fasteners and M5 through M20 for metric
measuring anvils. The fastener shall be rotated at least 360
fastenersindiameterandlessthanthreediametersinlengthfor
degrees to assure sound seating. At the position where the
product above ⁄4 in. and M20 in diameter, or that do not have
lowest value is indicated the instrument shall be zeroed or the
indicated measurement shall be recorded. If using a bolt sufficient threads for proper engagement and still leave the
specified number of complete threads exposed between the
extensometer, the bolt with attached extensometer may be
assembled into the tension testing machine. If not, mark the grips, shall be deemed too short for tension testing, and
acceptance shall be based on a hardness test performed in
fastener so it may be placed as close as possible to the same
position for the second reading. Remove and assemble the accordance with 3.1. If tests other than product hardness are
required, their requirements should be referenced in the prod-
fastener into the tension testing machine as outlined in 3.4.
With a test speed which shall not exceed 0.12 in./min for inch uct specification. When differences in tensile testing lengths
F606/F606M − 21
FIG. 2 Tension Testing of Full-Size Bolt (Typical Set-Up)
TABLE 1 Minimum Length of Product Requiring Tension Testing
threads exposed between the grips except for heavy hex
Nominal Minimum structural bolts, which shall have four complete threads ex-
Product Nominal
posed between the grips.
Size, in. Length, in.
3.4.2 Studs may be tested by assembling one end in the
1 5
⁄4 ⁄8
5 3
⁄16 ⁄4
threaded fixture to the thread runout. For studs having unlike
3 7
⁄8 ⁄8
threads,thisshallbetheendwiththefinerpitchthread,orwith
⁄16 1
1 1
the larger minor diameter. Likewise, assemble the other end of
⁄2 1 ⁄8
9 1
⁄16 1 ⁄4
the stud in a threaded fixture, leaving six complete threads
5 1
⁄8 1 ⁄2
exposed between the grips. For continuously threaded studs, at
3 3
⁄4 1 ⁄4
⁄8 and larger 3 dia
least six complete threads shall be exposed between the fixture
ends.The maximum speed of the free-running cross head shall
not exceed 1 in./min for inch fasteners and 25 mm/min for
exist between this standard and product standards, the require- metric fasteners. When reporting the tensile strength of inch
mentsoftheproductstandardshalltakeprecedence.Minimum
product, in pounds-force per square inch, calculate the thread
length in Table 1 indicates the nominal specified length of an
stress area as follows:
inch fastener (that is an A449 Hex Cap Screw size is specified
A 5 0.7854 @D 2 ~0.9743!/n# (1)
s
1 1 1
as ⁄2-13×1 ⁄8 indicates 1 ⁄8 in. is the nominal length) and
Table 2 for a metric fastener for size M12 ×30 indicates the where:
nominal length is 30 mm.
A = thread stress area, in. ,
s
D = nominal diameter of bolt or stud, in., and
3.4 Axial Tension Testing of Full-Size Products:
n = number of threads per inch.
3.4.1 Bolts may be tested in a holder with the load axially
applied between the head and a nut or suitable fixture (Fig. 2),
When reporting the tensile strength of metric product, in
either of which shall have sufficient thread engagement to
megapascals MPa calulate the thread stress area as follows:
develop the full strength of the product. Assemble the nut or
A 5 0.7854 D 2 0.9382 P (2)
@ ~ !#
s
fixtureontheproduct,leavingaminimumofsixcompletebolt
where:
TABLE 2 Minimum Length of Product Requiring Tension Testing A = thread stress area, mm ,
s
D = nominal diameter of bolt or stud, mm, and
Nominal Product Size, mm Minimum Nominal Length, mm
P = thread pitch, mm.
M5 12
M6 14
M8 20
3.4.3 Tomeettherequirementsofthetestdescribedin3.4.1
M10 25
and 3.4.2, the product shall support a load prior to fracture not
M12 30
less than the minimum tensile load specified in the product
M14 35
M16 40
specification for its size, strength, and thread series. In
M20 45
addition, unless otherwise specified, the tensile fracture shall
Over M20 3 dia
occur in the free threaded length. Fracture in the head or at the
F606/F606M − 21
existing stock has been depleted. Fasteners that are placed on order and
junction of the head and shank is prohibited at any load,
manufacturedaftertheissuanceofTestMethodsF606/F606M–16thatare
including those above the minimum requirements.
yield strength and wedge tensile tested shall follow the revised require-
3.4.3.1 For externally threaded fasteners, if the unthreaded
ment in 3.5.1.
shank diameter is reduced to be equal to or less than the basic
3.5.1.1 For externally threaded fasteners, if the unthreaded
thread pitch diameter, the fracture shall occur in the free
shank diameter is reduced to be equal to or less than the basic
threaded length or in the unthreaded shank.
thread pitch diameter, the fracture shall occur in the free
3.4.3.2 For screws threaded to the head, fracture that causes
threaded length or in the unthreaded shank.
failuremayextendorspreadintothetransitionsectionbetween
3.5.1.2 For screws threaded to the head, fracture that causes
the head and the thread, or into the head, before separation,
failuremayextendorspreadintothetransitionsectionbetween
provided that it originates in the free threaded length.
the head and the thread, or into the head, before separation,
3.4.3.3 Forfastenersmadeofnonhardenedsteel(thatis,not
provided that it originates in the free threaded length.
quench and tempered) or austenitic stainless steel, the fracture
3.5.1.3 Forfastenersmadeofnonhardenedsteel(thatis,not
shall occur in the free threaded length or in the unthreaded
quench and tempered) or austenitic stainless steel, the fracture
shank.
shall occur in the free threaded length or in the unthreaded
3.4.3.4 Forfastenersmadeofausteniticstainlesssteel,ifthe
shank.
test fastener’s thread pulls out of the internally threaded test
3.5.1.4 Forfastenersmadeofausteniticstainlesssteel,ifthe
fixture above the minimum specified tensile load, the fastener
test fastener’s thread pulls out of the internally threaded test
shall be considered conforming to the tensile strength require-
fixture above the minimum specified tensile load, the fastener
ment.
shall be considered conforming to the wedge tensile strength
3.5 WedgeTensionTestingofFull-SizeProduct—Thewedge
requirement.
tensile strength of a hex or square-head fastener, socket-head
NOTE 3—Fracture at the junction of the head and shank is prohibited at
cap screw (with the exception of socket button or flat counter-
any load, including those above the minimum requirements.
sunk head products) or stud is the tensile load that the product
is capable of sustaining when stressed with a wedge under the
3.5.2 Wedge Tension Testing of Studs—When both wedge
head. The purpose of this test is to obtain the tensile strength
tension and proof load testing are required by the product
and demonstrate the “head quality” and ductility of the
specifications, assemble one end of the same stud previously
product.
used for proof load testing in a threaded fixture to the thread
3.5.1 Wedge Tension Testing of Bolts—Determine the ulti- runout. For studs having unlike threads, this shall be the end
mate load of the bolt as described in 3.4 except place a wedge with the finer pitch thread or with the larger minor diameter.
under the bolt head. When both wedge tension and proof load Assemble the other end of the stud in a threaded wedge to the
testing are required by the product specification the bolts that runout and then unscrew six full turns, thus leaving six
have been the proof load-tested in accordance with Method 1 complete threads exposed between the grips, as illustrated in
(3.2.3) or Method 3 (3.2.5) may be used for wedge testing. Fig. 4. For continuous thread studs, at least six complete
Fasteners that have been yield strength tested utilizing either threadsshallbeexposedbetweenthefixtureends.Theangleof
Method2(3.2.4)orMethod2A(3.2.4.1)shallnotbereusedfor thewedgeforthestudsizeandgradeorpropertyclassshallbe
wedge testing. The wedge shall have a minimum hardness of as specified in Table 3 and Table 4. Assemble the stud in the
45 HRC. Additionally, the wedge shall have a minimum testingmachineandtensiontesttofracture,asdescribedin3.4.
thickness of one half the nominal bolt diameter (measured at The minimum hardness of the threaded wedge shall be 45
the thin side of the hole, see Fig. 3). The wedge shall have an HRC.The length of the threaded section of the wedge shall be
includedangleasshowninTable3andTable4fortheproduct equal to at least the diameter of the stud. To facilitate removal
typebeingtested.Theholeinthewedgeshallhaveaclearance ofthebrokenstud,thethreadedwedgemaybecounterboredon
over the nominal size of the bolt, and its top and bottom edges the faces as shown in Fig. 4.The thickness of the wedge at the
shall be rounded as specified in Table 5and Table 6. The thinsideoftheholeshallequalthediameterofthestudplusthe
minimum outside dimension of the wedge shall be such that depthofcounterbore.ThethreadinthewedgeshallhaveClass
during the test no corner loading of the product head (adjacent 3Btolerancesforinchpartsanda5Htoleranceformetricparts,
to the wedge) shall occur (see head orientation in Fig. 3). The except when testing studs having an interference fit thread, in
bolt shall be tension tested to fracture. To meet the require- which case the wedge shall be threaded to provide a finger-
ments of this test, the bolt shall support a load prior to fracture tight fit. The supporting fixture, as shown in Fig. 4, shall have
not less than the minimum tensile load specified in the product a hole clearance over the nominal size of the stud, and shall
specification for its size, strength, and thread series. In have its top and bottom edges rounded or chamfered to the
addition, unless otherwise specified, the tensile fracture shall same limits specified for the hardened wedge washers in Table
occur in the free thread length. Fracture in the head or at the 5 and Table 6. To meet the requirements of this test, the stud
junction of the head and shank is prohibited at any load, shallsupportaloadpriortofracturenotlessthantheminimum
including those above the minimum requirements. tensile strength specified in the product specification for its
size, grade, and thread series. When tensile testing externally
NOTE 2— Fasteners that have been manufactured/in-stock or on order
threadedfastenersmadeofausteniticstainlesssteelandthetest
prior to the approval of Test Methods F606/F606M–16 that utilized the
fastener’sthreadpullsoutoftheinternallythreadedtestfixture
same fastener for both yield strength and wedge tensile testing are
acceptable and may be supplied/used as-is without additional testing until after the minimum tensile strength requirement has been
F606/F606M − 21
c = clearance of hole
D = diameter of bolt or screw
R = radius or chamfer
T = reference thickness of wedge at thin side of hole equals one half diameter of bolt or
screw
W = wedge angle (see Table 3)
FIG. 3 Wedge Test Details—Bolts
TABLE 3 Tension Test Wedge Angles for Inch Bolts and Screws TABLE 4 Tension Test Wedge Angles for Metric Bolts and Screws
NOTE 1—For use with hardened and tempered steel and alloy steel NOTE 1—For use with hardened and tempered steel and alloy steel
standard products. For non-ferrous and special products, see the related standard products. For non-ferrous and special products, see the related
product specification. Unless otherwise specified, Table 3 shall apply. product specification.
Nominal Product Size, in. Degrees Nominal Product Size, mm. Degrees
A A
Bolts Studs and Bolts Studs and
Flange Bolts Flange Bolts
⁄4 –1 10 6 M5–M24 10 6
Over 1 6 4 Over M24 6 4
A
A
Heat-treated bolts that are threaded one diameter or closer to the underside of Heat-treated bolts that are threaded one diameter or closer to the underside of
1 3
the head, shall use a wedge angle of 6° for sizes ⁄4 through ⁄4 in. and 4° for sizes the head, shall use a wedge angle of 6° for sizes M5 through M20 and 4° for sizes
over ⁄4 in. over M20.
reached, the fasteners shall be considered conforming to the
tensile strength requirement. NOTE 4—Dimensional tolerances for all test fixtures used in this test
F606/F606M − 21
TABLE 5 Tensile Test Wedge Hole Clearance—Details for Inch
M16 through M30 for metric fasteners shall be machined with
Bolts and Screws
the axis of the specimen located midway between the center
and outside surface shown in Fig. 7.
NOTE 1—Fracture at the junction of the head and shank is prohibited at
any load, including those above the minimum requirements.
3.6.1.3 Bolts and studs 1 ⁄8 in. or M33 and larger may have
Nominal Product Nominal Clearance in Nominal Radius on
their shanks machined to test specimen with the axis of the
Size, in. Hole, in. Corners of Hole, in.
specimen located midway between the center and outside
1 1
⁄4 – ⁄2 0.030 0.030
surface of the bolt or stud as shown in Fig. 7 to sizes indicated
9 3
⁄16 – ⁄4 0.050 0.060
in Fig. 5 and Fig. 6 for inch and metric fasteners respectively.
⁄8 – 1 0.060 0.060
1 1
1 ⁄8–1 ⁄4 0.060 0.125
3.6.1.4 Machined test specimens shall exhibit tensile
3 1
1 ⁄8–1 ⁄2 0.094 0.125
strength, yield strength (or yield point), elongation, and reduc-
1 ⁄4 – 2 0.094 0.225
1 tion of area equal to or greater than the values of these
2 ⁄4 – 3 0.125 0.256
properties specified for the product size in the applicable
product specification when tested in accordance with this
TABLE 6 Tensile Test Wedge Hole Clearance—Details for Metric section.
Bolts and Screws
3.6.2 Determination of Tensile Properties:
3.6.2.1 Yield Point—Yield point is the first stress in a
NOTE 1—Fracture at the junction of the head and shank is prohibited at
any load, including those above the minimum requirements.
material, less than the maximum obtainable stress, at which an
Nominal Product Nominal Clearance in Nominal Radius on increase in strain occurs without an increase in stress. Yield
Size, mm. Hole, mm Corners of Hole, mm
point is intended for application only for materials that may
M5 and M6 0.50 0.70
exhibit the unique characteristic of showing an increase in
Over M6–M12 0.80 0.80
strainwithoutanincreaseinstress.Thestress-straindiagramis
Over M12–M20 1.60 1.30
characterizedbyasharpkneeordiscontinuity.Determineyield
Over M20–M36 3.20 1.60
Over M36 3.20 3.20
point by one of the following methods:
3.6.2.2 DropoftheBeamorHaltofthePointerMethod—In
this method apply an increasing load to the specimen at a
method, unless otherwise noted, shall conform to standard machining
uniformrate.Whenaleverandpoisemachineisused,keepthe
practices.
beam in balance by running out the poise at approximately a
3.6 Tension Testing of Machined Test Specimens:
steadyrate.Whentheyieldpointofthematerialisreached,the
3.6.1 Where bolts and studs cannot be tested full size,
increase of the load will stop, but run the poise a trifle beyond
conduct tests using test specimens machined from the bolt or
thebalanceposition,andthebeamofthemachinewilldropfor
stud (see Test Methods E8/E8M).
a brief but appreciable interval of time. When a machine
3.6.1.1 Boltsandstuds ⁄16in.andsmallermaybemachined
equipped with a load-indicating dial is used, there is a halt or
concentric with the axis of the bolt or stud for inch fasteners
hesitation of the load-indicating pointer corresponding to the
andM14formetricfasteners.Thespecimenshallhaveaturned
drop of the beam. Note the load at the “drop of the beam” or
section as large as feasible and shall have a gage length four
the “halt of the pointer” and record the corresponding stress as
times the diameter of the specimen for inch series and five
the yield point.
times the diameter of the specimen for metric series. See Fig.
3.6.2.3 Autographic Diagram Method—When a sharp-
5, Fig. 6.
kneed stress-strain diagram is obtained by an autographic
5 1
3.6.1.2 Boltsandstuds ⁄8in.indiameterthrough1 ⁄4in.for
recordingdevice,takethestresscorrespondingtothetopofthe
inch fasteners and M16 through M30 for metric fasteners may
knee(Fig.8),orthestressatwhichthecurvedropsastheyield
havetheirshanksmachinedconcentricwiththeaxisofthebolt
point (Fig. 9).
or stud, leaving the bolt head and threaded section intact as
3.6.2.4 Total Extension Under Load Method—When testing
shown in Fig. 5 and Fig. 6, however heat treated bolts in these
material for yield point and the test specimens may not exhibit
size ranges must not be reduced by more than 25% of their
a well-defined disproportionate deformation that characterizes
original diameter. Alternatively, bolts and studs ⁄8 in. in
a yield point as measured by the drop of the beam, halt of the
diameter through 1 ⁄4 in. for inch fasteners and M16 through
pointer, or autographic diagram methods described in 3.6.2.2
M30 for metric fasteners may have their shanks machined to a
and3.6.2.3,avalueequivalenttotheyieldpointinitspractical
test specimen with the axis of the specimen located midway
significance may be determined by the following method and
between the axis and outside surface of the bolt or stud as
may be recorded as yield point: Attach a Class C or better
shown in Fig. 7. Bolts of a small cross section that will not
extensometer (Note 5 and Note 6) to the specimen. When the
permit taking test specimens as shown in Fig. 5 or Fig. 6 for
load producing a specified extension (Note 7) is reached,
inch and metric fasteners respectively, shall have a turned
record the stress corresponding to the load as the yield point,
section as large as feasible and concentric with the axis of the
and remove the extensometer (Fig. 10).
boltorstud.Thegagelengthformeasuringtheelongationshall
NOTE5—Automaticdevicesareavailablethatdeterminetheloadatthe
be four times the diameter of the specimen for inch series and
specified total extension without plotting a stress-strain curve. Such
five times the diameter of the specimen for metric series. Fig.
devicesmaybeusediftheiraccuracyhasbeendemonstrated.Multiplying
5 and Fig. 6 illustrate an example of these small-size speci-
calipers and other such devices are acceptable for use provided their
mens. For arbitration purposes, machined test specimens for
accuracy has been demonstrated as equivalent to a Class C extensometer.
5 1
bolts and studs ⁄8 in. through 1 ⁄4 in. for inch fasteners and NOTE 6—Reference should be made to Practice E83.
F606/F606M − 21
C = clearance of hole,
D = diameter of stud,
R = radius or chamfer,
T = E plus depth of counterbore,
W = wedge angle,
E = length of threaded section of wedge =D
FIG. 4 Wedge Test Details—Studs
FIG. 5 Tension Test Specimen for Bolt with Turned-Down Shank for Inch Bolts
NOTE 7—For steel inch fasteners with a specified yield point not over
beforeorattheintersectionofmnwithr.Inreportingvaluesof
80000 psi, an appropriate value is 0.005 in./in. of gage length. For values
yield strength obtained by this method, the specified value of
above 80000 psi, this test method is not valid unless the limiting total
“offset” used should be stated in parentheses after the term
extension is increased. For steel metric fasteners with a specified yield
yield strength. For inch fasteners:
point not over 550 MPa, an appropriate value is 0.13 mm/mm of gauge
length. For values above 550 MPa, this test method is not valid unless the
Yieldstrength 0.2% offset 5 52000psi (3)
~ !
limiting total extension is increased.
For metric fasteners:
3.6.3 Yield Strength—Yield strength is the stress at which a
Yieldstrength 0.2% offset 5 360 MPa (4)
~ !
material exhibits a specified limiting deviation from the pro-
In using this method, a minimum extensometer magnification
portionality of stress to strain. The deviation is expressed in
of 250 to 1 is required. A Class B1 extensometer meets this
terms of strain, percent offset, total extension under load, etc.
requirement (see Note 6). See also Note 5 for automatic de-
Determine yield strength by one of the following methods:
vices.
3.6.3.1 Offset Method—To determine the yield strength by
3.6.3.2 Extension Under Load Method—For tests to deter-
the “offset method,” it is necessary to secure data (autographic
or numerical) from which a stress-strain diagram may be minetheacceptanceorrejectionofmaterialwhosestress-strain
characteristics are well known from previous tests of similar
drawn. Then on the stress-strain diagram (Fig. 8) lay off om
equal to the specified value of the offset, draw mn parallel to material in which stress-strain diagrams were plotted, the total
oA, and thus locate r. The yield strength load R is the load strain corresponding to the stress at which the specified offset
corresponding to the highest point of the stress-strain curve (see Note 8) occurs will be known within satisfactory limits.
F606/F606M − 21
D = nominal thread diameter,
D = diameter of test piece (D < minor diameter of thread),
O O
B = length of thread (B$ D),
L =5D or (5.65 S ),
O O œ O
L = length of straight portion (L +D ),
C O O
L = total length of test piece (L +2 +B),
T C R
L = length after fracture,
U
S = cross-sectional area, and
O
R = fillet radius (R$ 4mm)
FIG. 6 Tension Specimens with Turned-down Shank for Metric Bolts
FIG. 8 Stress-Strain Diagram for Determination of Yield
FIG. 7 Location of Standard Round 2-in. Gage Length Tension
Strength by the Offset Method
Test Specimen When Turned from Large Size Bolt
test. In general, the value of extension under load applicable to any
The stress on the specimen, when this total strain is reached, is
material strength level may be determined from the sum of the propor-
the value of the yield strength.The total strain can be obtained
tional strain and the plastic strain expected at the specified yield strength.
The following equation is used:
satisfactorily by use of a Class B1 extensometer (Note 5 and
Extensionunderload,in./in.ofgagelengthforinchfastenersandmm/mm
Note 6).
of gage length for metric fasteners = (YS/E)= r
NOTE 8—The appropriate magnitude of the extension under load will where:
obviously vary with the strength range of the particular material under YS = specified yield strength, psi for inch fasteners and MPa for metric
F606/F606M − 21
r = limitingplasticstrain,in./inforinchfastenersandmm/mmformetric
fasteners.
3.6.4 Tensile Strength—Calculate the tensile strength by
dividing the maximum load the specimen sustains during a
tension test by the original cross-sectional area of the speci-
men.
3.6.5 Elongation:
3.6.5.1 Fit the ends of the fractured specimen together
carefully and measure the distance between the gage marks to
the nearest 0.01 in. for gage lengths through 2 in. or 0.25 mm
through 50 mm gauge length. Measure to the nearest 0.5% of
longer gage lengths.The elongation is the increase in length of
the gage length, expressed as a percentage of the original gage
length.Inreportingelongationvalues,giveboththepercentage
increase and the original gage length.
3.6.5.2 If any part of the fracture takes place outside of the
middle half of the gage length or in a punched or scribed mark
within the reduced section, the elongation value obtained may
FIG. 9 Stress-Strain Diagram Showing Yield Point
not be representative of the material. If the elongation so
Corresponding with Top of Knee
measured meets the minimum requirements specified, no
furthertestingisindicated,butiftheelongationislessthanthe
minimum requirements, discard the test and retest.
3.6.6 Reduction of Area—Fit the ends of the fractured
specimentogetherandmeasurethemeandiameterorthewidth
andthicknessatthesmallestcrosssectiontothesameaccuracy
as the original dimensions. The difference between the area
thus found and the area of the original cross section expressed
as a percentage of the original area, is the reduction of area.
3.7 Total Extension at Fracture Test:
3.7.1 Theextensionatfracture(A )testshallbecarriedout
L
on stainless steel and nonferrous products (bolts, screws, and
studs) in the finished condition, with lengths equal to or in
excess of those minimums listed in Table 1 and Table 2.
3.7.2 The products to be tested shall be measured for total
length (L ) as described in 3.7.2.1 and shown in Fig. 11.
3.7.2.1 Mark both ends of the bolt, screw, or stud using a
permanentmarkingsubstancesuchasbluingsothatmeasuring
reference points for determining total length L and L are
1 2
established. Using an open-end caliper and steel rule or other
FIG. 10 Stress-Strain Diagram Showing Yield Point or Yield
device capable of measuring to within 0.010 in., or 0.25 mm,
Strength by Extension Under Load Method
determine the total length of the product as shown in Fig. 11.
3.7.3 The product under test shall be screwed into the
fasteners,
threaded adapter to a depth of one diameter (see Fig. 2) and
E = modulus of elasticity, psi for inch fasteners and MPa for metric
fasteners, and load applied axially until the product fractures. The maximum
FIG. 11 Determination of Total Extension at Fracture (A )
L
(only Screw Product Shown)
F606/F606M − 21
speed of the free-running cross head shall not exceed 1 in./min
for inch fasteners and 25 mm/min for metric fasteners.
3.7.4 After the product has been fractured in accordance
with 3.7.3, the two broken pieces shall be fitted closely
together and the overall length (L ) measured (see 3.7.2.1 and
Fig.11).Thetotalextensionatfractureshallthenbecalculated
as follows:
A = L − L
L 2 1
3.7.5 Thevalueobtainedshallequalorexceedtheminimum
valuesshownintheapplicablespecificationfortheproductand
material type.
3.8 Single Shear Test—(Note 9) This test is intended to
determinetheabilityofafastenertowithstandapredetermined
loadwhenappliedtransverselytotheaxisofthefastener.Shear
is defined as an action or stress caused by applied forces that
causes two adjacent parts of a body to slide on each other to
cause separation. Shear tests may be conducted in either
FIG. 12 Typical Single Shear Fixture (Tension Type)
tension-type or compression-type single shear fixture.
3.8.1 The specimen shall be tested using hardened steel
manufacturer, taking into account the size and grade or
plates of sufficient thickness to preclude bearing failure. Holes
property class of the product.
in the shear plates shall be ⁄16 in. larger than the nominal body
4.1.1 The preparation of test specimens and the perfor-
diameter or nominal thread diameter of the test bolt for inch
mance of hardness tests for Rockwell and Brinell testing shall
fasteners and 1.5 mm for metric fasteners. The holes shall be
be in conformance with the requirements ofTest Methods E18
chamfered 0.010 in. or 0.25 mm to relieve sharp edges. Shear
and E10, respectively.
plates shall be prevented from separating by means of a
4.1.2 Readings when taken on the bearing face shall be
suitable jig or by using a nut on the test bolt tightened finger
halfway between the major diameter of the thread and one
tight.
corner. The reported hardness shall be the average of two
3.8.2 The test specimen, when assembled in the shear jig,
hardnessreadingslocated180°apart.Thereadingswhentaken
shall be mounted in a tensile-testing machine capable of
on the wrench flats shall be one third of the distance from a
applying load at a controllable rate. The grips shall be
corner to the center of the wrench face. The reported harness
self-aligning and care shall be taken when mounting the
shall be the average of two readings located from opposite
specimentoassurethattheloadwillbetransmittedinastraight
corners.
line transversely through the test bolt. Load shall be applied
4.1.3 For the purpose of arbitration or for nuts too large for
and continued until fracture of the bolt. Speed of testing as
full size testing, where hardness alone shall determine accep-
determinedwithafree-runningcrossheadshallnotbelessthan
tance (see 4.1.4), the following shall apply.
1 1
⁄4 in. 6.0 mm nor greater than ⁄2 in./min or 12.0 mm/min.
4.1.3.1 Sample nuts shall be sectioned laterally at approxi-
3.8.3 The maximum load applied to the specimen, coinci-
mately one half ( ⁄2) of the nut height. Such samples need not
dentwithorpriortoboltfractureshallberecordedastheshear
be threaded, but shall be part of the manufacturing lot that was
strength of the bolt. At the discretion of the testing activity,
formed (in the case of heat-treated nuts, formed and heat-
tests need not be continued to destruction provided that the
treated) with the product to be shipped. The preparation of the
specimen supports, without evidence of bolt fracture, the
sample shall be in accordance with 4.1.1 above. All readings
minimum load specified.
shall be conducted on a Rockwell Hardness testing machine.
3.8.4 Atypicaltestfixturefortensionsheartestingisshown
Forstandardhex,heavyhexandsquarenuts,thehalfofthenut
in Fig. 12.
not to be tested may be discarded. For special nut configura-
NOTE 9—This single-shear test is primarily used for testing Specifica-
tionsbothsectionsshallbeidentifiedandmadeavailabletothe
tion A394 tower bolts which range in size from ⁄2 through 1 in. diameter.
purchaser, if specified on the purchase order or inquiry.
For general use, the shear test practices and fixturing found in MIL STD
4.1.3.2 Nonheat-Treated Nuts (See Fig. 13)—Two readings
1312 Test 13 is used for double shear and Test 20 may be used for single
shall be taken 180° apart at the core (halfway between the
shear.
major diameter if threaded, or blank hole if not threaded) and
4. Test Methods for Internally Threaded Fasteners
a corner of the nut. The reported hardness shall be the average
4.1 Product Hardness—For routine inspection of both heat- of the two readings, and in addition both readings shall be
treated and nonheat-treated nuts, hardness shall be determined within the hardness values listed in the product specification.
on the bearing face or wrench flats after removal of any oxide, 4.1.3.3 Heat-Treated Nuts (See Fig. 14)—Two sets of three
decarburization,plating,orothercoatingmaterial.Rockwellor readings 180° apart shall be taken. The three readings shall be
Brinell hardness shall be used at the option of the taken across the section of the nut at the following positions:
F606/F606M − 21
4.1.3.4 The reported hardness shall be the average of all six
readings. In addition all readings shall be within hardness
values listed in the product specification.
4.1.4 Nutsexhibitingaproofloadinexcessof160000lbfor
inch nuts or 700 kN for metric nuts may be considered, at the
option of the manufacturer, as too large for full-size testing.
Full-size testing is recommended whenever possible.
4.1.5 For nuts on which hard
...

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: F606/F606M − 19 F606/F606M − 21
Standard Test Methods for
Determining the Mechanical Properties of Externally and
Internally Threaded Fasteners, Washers, Direct Tension
Indicators, and Rivets
This standard is issued under the fixed designation F606/F606M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 These test methods cover establishment of procedures for conducting tests to determine the mechanical properties of externally
and internally threaded fasteners, washers, direct tension indicators, and rivets.
1.2 Property requirements and the applicable tests for their determination are specified in individual product standards. In those
instances where the testing requirements are unique or at variance with these standard procedures, the product standard shall
specify the controlling testing requirements. In the absence of any specified test requirement(s), these test methods shall apply.
1.3 These test methods describe mechanical tests for determining the following properties:
Section
For Externally Threaded Fasteners: 3
Product Hardness 3.1
Proof Load 3.2.1
Method 1, Length Measurement 3.2.3
Method 2, Yield Strength 3.2.4
Method 3, Uniform Hardness 3.2.5
Axial Tension Testing of Full-Size Product 3.4
Wedge Tension Testing of Full-Size Product 3.5
Tension Testing of Machined Test Specimens 3.6
Total Extension at Fracture Test 3.7
Single Sheer Test 3.8
For Internally Threaded Fasteners: 4
Product Hardness 4.1
Proof Load Test 4.2
Cone Proof Load Test 4.3
For Washers and Direct Tension Indicators: 5
Product Hardness-General Requirements 5.1
Through Hardened Washers 5.2
Carburized Washers 5.3
Stainless Steel and Nonferrous Washers 5.4
Direct Tension Indicators 5.5
Compression Load 5.6
For Rivets: 6
Product Hardness 6.1
These test methods are under the jurisdiction of ASTM Committee F16 on Fasteners and are the direct responsibility of Subcommittee F16.01 on Test Methods.
Current edition approved Nov. 15, 2019June 1, 2021. Published January 2020June 2021. Originally approved in 1979. Last previous edition approved in 20162019 as
F606/F606M – 16.F606/F606M – 19. DOI: 10.1520/F0606_F0606M-19.10.1520/F0606_F0606M-21.
*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
F606/F606M − 21
Test for Embrittlement of Metallic-Coated Externally Threaded 7
Fasteners
Test Method for Determining Decarburization and Carburization 8
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
NOTE 1—The values are stated in inch-pound for inch fasteners and SI metric units for metric fasteners.
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.
2. Referenced Documents
2.1 ASTM Standards:
A394 Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
E4 Practices for Force Verification of Testing Machines
E8/E8M Test Methods for Tension Testing of Metallic Materials
E10 Test Method for Brinell Hardness of Metallic Materials
E18 Test Methods for Rockwell Hardness of Metallic Materials
E83 Practice for Verification and Classification of Extensometer Systems
E92 Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials
E384 Test Method for Microindentation Hardness of Materials
F436/F436M Specification for Hardened Steel Washers Inch and Metric Dimensions
F959 Specification for Compressible-Washer-Type Direct Tension Indicators for Use With Structural Fasteners (Metric)
F0959_F0959M
F1624 Test Method for Measurement of Hydrogen Embrittlement Threshold in Steel by the Incremental Step Loading Technique
F2328 Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts,
Screws, Studs, and Nuts
F2328M Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts,
Screws, Studs, and Nuts (Metric)
2.2 Military Standard:
MIL STD 1312, Test 13 and Test 20
3. Test Methods for Externally Threaded Fasteners
3.1 Product Hardness—Tests shall be conducted after the removal of any surface oxide, decarburization, plating or other coating.
All readings shall be within the hardness values listed in the product specification. The average of all readings on the same part
shall be considered as the product hardness. Test results shall conform to the product specification for the lot represented by the
test specimens to be considered conforming. Test specimen preparation and hardness tests shall be conducted in accordance with
Test Methods E18 for Rockwell tests, Test Method E10 for Brinell tests, Test Method E92 for Vickers tests, or Test Method E384
for Microhardness tests. The method used is at the option of the manufacturer, with regards to the size and grade of the products.
3.1.1 Routine Test Locations—For testing the hardness of the finished product, the following test locations can be used:
3.1.1.1 For hex and square head bolts; test shall be conducted on the wrench flats, top of head, unthreaded shank, end of bolt or
at the arbitration location.
3.1.1.2 For studs, products without parallel wrench flats and for head styles other than hex and square; tests shall be conducted
on the unthreaded shank, end of the bolt or stud or at the arbitration location.
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 the ASTM website.
DLA Document Services Building 4/D 700 Robbins Avenue Philadelphia, PA 19111-5094 http://quicksearch.dla.mil/
F606/F606M − 21
3.1.1.3 Stress relieved products (3.1.1.1 and 3.1.1.2) are measured anywhere on the surface or through the cross section. Refer to
the product specification for particular test location or use the arbitration location.
3.1.1.4 The Rockwell Hardness Scale may be used for all product diameters; however, the Brinell hardness is limited to products
over 1 ⁄2-in. or M36.
3.1.2 Laboratory Inspection—A minimum of three readings shall be taken on each sample of finished product.
3.1.3 Arbitration Test Location—For purposes of arbitration between the purchaser and seller over reported test results, hardness
tests shall be conducted at the mid-radius (r/2) of a transverse section through the threads taken at a distance of approximately one
diameter from the point end of the bolt or one end of the stud. Four readings shall be taken from the point end of the bolt or one
end of the stud. Four readings shall be taken approximately 90° to one another on the same plane, if product size permits. Smaller
diameter products may also use the opposite parallel surface area of the bolt head end as sectioned above (see Fig. 1). The use of
Brinell hardness for arbitration testing is limited to product sizes greater than 2 ⁄4-in. or M60.
3.2 Tension Tests—It is preferred that bolts and studs be tested full size, and it is customary, when so testing, to specify a minimum
ultimate load (or stress) in pounds-force (or pounds-force per square inch.) for inch fasteners and or load in newtons-force or
megapascals MPa for metric fasteners. Sections 3.2 – 3.5 apply when testing externally threaded fasteners full size. Section 3.6
shall apply where the individual product specifications permit the use of machined specimens (see Test Methods E8/E8M).
3.2.1 Proof Load—The proof-load test consists of stressing the product with a specified load that the product must withstand
without measurable permanent set. Alternative tests for determining the ability of a fastener to pass the proof-load test are the yield
strength test and the uniform hardness test. Either Method 1 (3.2.3), Method 2 (3.2.4), or Method 3 (3.2.5) may be used, but
Method 1 shall be the arbitration method in case of any dispute as to acceptance of the product (see Test Methods E8/E8M).
3.2.2 In both Methods 1 and 2, assemble the product in the fixture of the tension testing machine so that six complete threads
(except for heavy hex structural bolts, which shall be based on four threads) are exposed between the grips. This is obtained by
freely running the nut or fixture to the thread runout of the specimen and then unscrewing the specimen six full turns. For
continuous thread bolts, at least six full threads shall be exposed between the fixture ends; however, for referee purposes, six full
threads shall be exposed.
3.2.3 Method 1, Length Measurement—To ensure consistent and repetitive length measurements of the fastener, the threaded end
and top of the bolt head shall have conical depressions made at the approximate axis or center line of the fastener. In the event
of a dispute over test results the test shall be conducted after the removal of all manufacturer or grade markings, surface oxide,
decarburization, plating, other coating, or a combination thereof, to achieve a clean, flat surface and the conical depressions shall
be created using a lathe or some type of centering fixture. All debris shall be removed from the conical depressions before
FIG. 1 Hardness Arbitration Test Location
F606/F606M − 21
measuring the part. When fasteners are too long to test in the available equipment the fastener may be cut to 8 inches 6 0.125
for inch fasteners or a length of 200 mm 6 3.0 mm for metric fasteners and tested using Method 1. If there is a dispute over results
when testing the same part or lot of parts, both full size and cut fastener the cut fastener results shall be used to determine
acceptance. The measuring instrument shall have pointed anvils which mate with the center line depressions and be capable of
measuring changes in length of 0.0001 in. for inch fasteners and 0.0025 mm for metric fasteners. The instrument accuracy shall
be within 0.0001 in. in any 0.001 in. range for inch parts and within 0.0025 mm accuracy within any 0.025 mm range for metric
parts. Place the fastener between the measuring anvils. The fastener shall be rotated at least 360 degrees to assure sound seating.
At the position where the lowest value is indicated the instrument shall be zeroed or the indicated measurement shall be recorded.
If using a bolt extensometer, the bolt with attached extensometer may be assembled into the tension testing machine. If not, mark
the fastener so it may be placed as close as possible to the same position for the second reading. Remove and assemble the fastener
into the tension testing machine as outlined in 3.4. With a test speed which shall not exceed 0.12 in./min for inch fasteners and
3.0 mm/min for metric fasteners, as determined with a free-running cross head, axially load the fastener to the proof load value
specified in the product specification. This load shall be maintained for a period of 10 s before releasing the load. Replace the
fastener between the measuring anvils and rotate at least 360 degrees as before. The fastener shall be stopped at the position where
the lowest value is indicated. The measurement shall show no permanent elongation. A tolerance of 60.0005 in. for inch fasteners
and 6 0.013 mm for metric fasteners shall be allowed (for measurement error only) between the measurement made before loading
and that made after loading. Variables such as straightness, thread alignment, or measurement error could result in apparent
elongation of the product when the specified proof load is initially applied. In such cases, the product may be retested using a 3 %
greater load, and shall be considered acceptable if there is no difference in the length measurement after this loading within a
0.0005 in. for inch fasteners and 6 0.013 mm for metric fasteners, measurement tolerance as outlined.
3.2.4 Method 2, Yield Strength—Assemble the product in the testing equipment as outlined in 3.4. As the load is applied, measure
and record the total elongation of the product or any part of it that includes the exposed threads to produce a load-elongation
diagram. Determine the load or stress at an offset equal to 0.2 % of the length of bolt occupied by six full threads as shown in Fig.
2 (except for heavy hex structural bolts, which shall be based on four threads) by the method described in 3.6.3.1.
3.2.4.1 Method 2A, Yield Strength for Austenitic Stainless Steel and Non-ferrous Materials—Assemble the product in the testing
equipment as outlined in 3.4. As the load is applied, measure and record the total elongation of the product in order to produce
a load elongation diagram. Determine the load or stress at an offset equal to 0.2 % strain based on the length of the bolt between
the holders as shown in Fig. 2, which will be subject to elongation under load by using the method described in 3.6.3.1.
3.2.5 Method 3, Uniform Hardness—The fasteners shall be tested for hardness as described in 3.1, and in addition, the hardness
shall also be determined in the core. The difference between the mid-radius and core hardness shall be not more than 3 points on
a Rockwell C Scale; and both readings must be within product specification. This test is valid for fasteners up to and including
1 in. for inch fasteners and M24 diameter for metric fasteners.
FIG. 2 Tension Testing of Full-Size Bolt (Typical Set-Up)
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1 3
3.3 Bolts or Studs Too Short for Tension Testing—Product lengths less than those shown in Table 1 for product ⁄4 through ⁄4 in.
for inch fasteners and M5 through M20 for metric fasteners in diameter and less than three diameters in length for product above
⁄4 in. and M20 in diameter, or that do not have sufficient threads for proper engagement and still leave the specified number of
complete threads exposed between the grips, shall be deemed too short for tension testing, and acceptance shall be based on a
hardness test performed in accordance with 3.1. If tests other than product hardness are required, their requirements should be
referenced in the product specification. When differences in tensile testing lengths exist between this standard and product
standards, the requirements of the product standard shall take precedence. Minimum length in Table 1 indicates the nominal
1 1 1
specified length of an inch fastener (that is an A449 Hex Cap Screw size is specified as ⁄2-13 × 1 ⁄8 indicates 1 ⁄8 in. is the nominal
length) and Table 2 for a metric fastener for size M12 ×30 indicates the nominal length is 30 mm.
3.4 Axial Tension Testing of Full-Size Products:
3.4.1 Bolts may be tested in a holder with the load axially applied between the head and a nut or suitable fixture (Fig. 2), either
of which shall have sufficient thread engagement to develop the full strength of the product. Assemble the nut or fixture on the
product, leaving a minimum of six complete bolt threads exposed between the grips except for heavy hex structural bolts, which
shall have four complete threads exposed between the grips.
3.4.2 Studs may be tested by assembling one end in the threaded fixture to the thread runout. For studs having unlike threads, this
shall be the end with the finer pitch thread, or with the larger minor diameter. Likewise, assemble the other end of the stud in a
threaded fixture, leaving six complete threads exposed between the grips. For continuously threaded studs, at least six complete
threads shall be exposed between the fixture ends. The maximum speed of the free-running cross head shall not exceed 1 in./min
for inch fasteners and 25 mm/min for metric fasteners. When reporting the tensile strength of inch product, in pounds-force per
square inch, calculate the thread stress area as follows:
A 5 0.7854 @D 2 ~0.9743!/n# (1)
s
where:
A = thread stress area, in. ,
s
D = nominal diameter of bolt or stud, in., and
n = number of threads per inch.
When reporting the tensile strength of metric product, in megapascals MPa calulate the thread stress area as follows:
A 5 0.7854 @D 2 ~0.9382 P!# (2)
s
where:
A = thread stress area, mm ,
s
D = nominal diameter of bolt or stud, mm, and
P = thread pitch, mm.
3.4.3 To meet the requirements of the test described in 3.4.1 and 3.4.2, the product shall support a load prior to fracture not less
than the minimum tensile load specified in the product specification for its size, strength, and thread series. In addition, unless
otherwise specified, the tensile fracture shall occur in the free threaded length. Fracture in the head or at the junction of the head
and shank is prohibited at any load, including those above the minimum requirements.
TABLE 1 Minimum Length of Product Requiring Tension Testing
Nominal Minimum
Product Nominal
Size, in. Length, in.
1 5
⁄4 ⁄8
5 3
⁄16 ⁄4
3 7
⁄8 ⁄8
⁄16 1
1 1
⁄2 1 ⁄8
9 1
⁄16 1 ⁄4
5 1
⁄8 1 ⁄2
3 3
⁄4 1 ⁄4
⁄8 and larger 3 dia
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TABLE 2 Minimum Length of Product Requiring Tension Testing
Nominal Product Size, mm Minimum Nominal Length, mm
M5 12
M6 14
M8 20
M10 25
M12 30
M14 35
M16 40
M20 45
Over M20 3 dia
3.4.3.1 For externally threaded fasteners, if the unthreaded shank diameter is reduced to be equal to or less than the basic thread
pitch diameter, the fracture shall occur in the free threaded length or in the unthreaded shank.
3.4.3.2 For screws threaded to the head, fracture that causes failure may extend or spread into the transition section between the
head and the thread, or into the head, before separation, provided that it originates in the free threaded length.
3.4.3.3 For fasteners made of non hardened steel (that is, not quench and tempered) or austenitic stainless steel, the fracture shall
occur in the free threaded length or in the unthreaded shank.
3.4.3.4 For fasteners made of austenitic stainless steel, if the test fastener’s thread pulls out of the internally threaded test fixture
above the minimum specified tensile load, the fastener shall be considered conforming to the tensile strength requirement.
3.5 Wedge Tension Testing of Full-Size Product—The wedge tensile strength of a hex or square-head fastener, socket-head cap
screw (with the exception of socket button or flat countersunk head products) or stud is the tensile load that the product is capable
of sustaining when stressed with a wedge under the head. The purpose of this test is to obtain the tensile strength and demonstrate
the “head quality” and ductility of the product.
3.5.1 Wedge Tension Testing of Bolts—Determine the ultimate load of the bolt as described in 3.4 except place a wedge under the
bolt head. When both wedge tension and proof load testing are required by the product specification the bolts that have been the
proof load-tested in accordance with Method 1 (3.2.3) or Method 3 (3.2.5) may be used for wedge testing. Fasteners that have been
yield strength tested utilizing either Method 2 (3.2.4) or Method 2A (3.2.4.1) shall not be reused for wedge testing. The wedge shall
have a minimum hardness of 45 HRC. Additionally, the wedge shall have a minimum thickness of one half the nominal bolt
diameter (measured at the thin side of the hole, see Fig. 3). The wedge shall have an included angle as shown in Table 3 and Table
4 for the product type being tested. The hole in the wedge shall have a clearance over the nominal size of the bolt, and its top and
bottom edges shall be rounded as specified in Table 5and Table 6. The minimum outside dimension of the wedge shall be such
that during the test no corner loading of the product head (adjacent to the wedge) shall occur (see head orientation in Fig. 3). The
bolt shall be tension tested to fracture. To meet the requirements of this test, the bolt shall support a load prior to fracture not less
than the minimum tensile load specified in the product specification for its size, strength, and thread series. In addition, unless
otherwise specified, the tensile fracture shall occur in the free thread length. Fracture in the head or at the junction of the head and
shank is prohibited at any load, including those above the minimum requirements.
NOTE 2— Fasteners that have been manufactured/in-stock or on order prior to the approval of Test Methods F606/F606M–16 that utilized the same
fastener for both yield strength and wedge tensile testing are acceptable and may be supplied/used as-is without additional testing until existing stock has
been depleted. Fasteners that are placed on order and manufactured after the issuance of Test Methods F606/F606M–16 that are yield strength and wedge
tensile tested shall follow the revised requirement in 3.5.1.
3.5.1.1 For externally threaded fasteners, if the unthreaded shank diameter is reduced to be equal to or less than the basic thread
pitch diameter, the fracture shall occur in the free threaded length or in the unthreaded shank.
3.5.1.2 For screws threaded to the head, fracture that causes failure may extend or spread into the transition section between the
head and the thread, or into the head, before separation, provided that it originates in the free threaded length.
3.5.1.3 For fasteners made of non hardened steel (that is, not quench and tempered) or austenitic stainless steel, the fracture shall
occur in the free threaded length or in the unthreaded shank.
3.5.1.4 For fasteners made of austenitic stainless steel, if the test fastener’s thread pulls out of the internally threaded test fixture
above the minimum specified tensile load, the fastener shall be considered conforming to the wedge tensile strength requirement.
F606/F606M − 21
c = clearance of hole
D = diameter of bolt or screw
R = radius or chamfer
T = reference thickness of wedge at thin side of hole equals one half diameter of bolt or
screw
W = wedge angle (see Table 3)
FIG. 3 Wedge Test Details—Bolts
TABLE 3 Tension Test Wedge Angles for Inch Bolts and Screws
NOTE 1—For use with hardened and tempered steel and alloy steel
standard products. For non-ferrous and special products, see the related
product specification. Unless otherwise specified, Table 3 shall apply.
Nominal Product Size, in. Degrees
A
Bolts Studs and
Flange Bolts
⁄4 –1 10 6
Over 1 6 4
A
Heat-treated bolts that are threaded one diameter or closer to the underside of
1 3
the head, shall use a wedge angle of 6° for sizes ⁄4 through ⁄4 in. and 4° for sizes
over ⁄4 in.
F606/F606M − 21
TABLE 4 Tension Test Wedge Angles for Metric Bolts and Screws
NOTE 1—For use with hardened and tempered steel and alloy steel
standard products. For non-ferrous and special products, see the related
product specification.
Nominal Product Size, mm. Degrees
A
Bolts Studs and
Flange Bolts
M5–M24 10 6
Over M24 6 4
A
Heat-treated bolts that are threaded one diameter or closer to the underside of
the head, shall use a wedge angle of 6° for sizes M5 through M20 and 4° for sizes
over M20.
TABLE 5 Tensile Test Wedge Hole Clearance—Details for Inch
Bolts and Screws
NOTE 1—Fracture at the junction of the head and shank is prohibited at
any load, including those above the minimum requirements.
Nominal Product Nominal Clearance in Nominal Radius on
Size, in. Hole, in. Corners of Hole, in.
1 1
⁄4 – ⁄2 0.030 0.030
9 3
⁄16 – ⁄4 0.050 0.060
⁄8 – 1 0.060 0.060
1 1
1 ⁄8 – 1 ⁄4 0.060 0.125
3 1
1 ⁄8 – 1 ⁄2 0.094 0.125
1 ⁄4 – 2 0.094 0.225
2 ⁄4 – 3 0.125 0.256
TABLE 6 Tensile Test Wedge Hole Clearance—Details for Metric
Bolts and Screws
NOTE 1—Fracture at the junction of the head and shank is prohibited at
any load, including those above the minimum requirements.
Nominal Product Nominal Clearance in Nominal Radius on
Size, mm. Hole, mm Corners of Hole, mm
M5 and M6 0.50 0.70
Over M6–M12 0.80 0.80
Over M12–M20 1.60 1.30
Over M20–M36 3.20 1.60
Over M36 3.20 3.20
NOTE 3—Fracture at the junction of the head and shank is prohibited at any load, including those above the minimum requirements.
3.5.2 Wedge Tension Testing of Studs—When both wedge tension and proof load testing are required by the product specifications,
assemble one end of the same stud previously used for proof load testing in a threaded fixture to the thread runout. For studs having
unlike threads, this shall be the end with the finer pitch thread or with the larger minor diameter. Assemble the other end of the
stud in a threaded wedge to the runout and then unscrew six full turns, thus leaving six complete threads exposed between the grips,
as illustrated in Fig. 4. For continuous thread studs, at least six complete threads shall be exposed between the fixture ends. The
angle of the wedge for the stud size and grade or property class shall be as specified in Table 3 and Table 4. Assemble the stud
in the testing machine and tension test to fracture, as described in 3.4. The minimum hardness of the threaded wedge shall be 45
HRC. The length of the threaded section of the wedge shall be equal to at least the diameter of the stud. To facilitate removal of
the broken stud, the threaded wedge may be counterbored on the faces as shown in Fig. 4. The thickness of the wedge at the thin
side of the hole shall equal the diameter of the stud plus the depth of counterbore. The thread in the wedge shall have Class 3B
tolerances for inch parts and a 5H tolerance for metric parts, except when testing studs having an interference fit thread, in which
case the wedge shall be threaded to provide a finger-tight fit. The supporting fixture, as shown in Fig. 4, shall have a hole clearance
over the nominal size of the stud, and shall have its top and bottom edges rounded or chamfered to the same limits specified for
the hardened wedge washers in Table 5 and Table 6. To meet the requirements of this test, the stud shall support a load prior to
fracture not less than the minimum tensile strength specified in the product specification for its size, grade, and thread series. When
tensile testing externally threaded fasteners made of austenitic stainless steel and the test fastener’s thread pulls out of the internally
threaded test fixture after the minimum tensile strength requirement has been reached, the fasteners shall be considered conforming
to the tensile strength requirement.
F606/F606M − 21
C = clearance of hole,
D = diameter of stud,
R = radius or chamfer,
T = E plus depth of counterbore,
W = wedge angle,
E = length of threaded section of wedge =D
FIG. 4 Wedge Test Details—Studs
NOTE 4—Dimensional tolerances for all test fixtures used in this test method, unless otherwise noted, shall conform to standard machining practices.
3.6 Tension Testing of Machined Test Specimens:
3.6.1 Where bolts and studs cannot be tested full size, conduct tests using test specimens machined from the bolt or stud (see Test
Methods E8/E8M).
3.6.1.1 Bolts and studs ⁄16 in. and smaller may be machined concentric with the axis of the bolt or stud for inch fasteners and M14
for metric fasteners. The specimen shall have a turned section as large as feasible and shall have a gage length four times the
diameter of the specimen. specimen for inch series and five times the diameter of the specimen for metric series. See Fig. 5, Fig.
6.
5 1
3.6.1.2 Bolts and studs ⁄8 in. in diameter through 1 ⁄4 in. for inch fasteners and M16 through M30 for metric fasteners may have
their shanks machined concentric with the axis of the bolt or stud, leaving the bolt head and threaded section intact as shown in
Fig. 5 and Fig. 6, however heat treated bolts in these size ranges must not be reduced by more than 25%25 % of their original
5 1
diameter. Alternatively, bolts and studs ⁄8 in. in diameter through 1 ⁄4 in. for inch fasteners and M16 through M30 for metric
fasteners may have their shanks machined to a test specimen with the axis of the specimen located midway between the axis and
outside surface of the bolt or stud as shown in Fig. 7. Bolts of a small cross section that will not permit taking test specimens as
shown in Fig. 5 or Fig. 6 for inch and metric fasteners respectively, shall have a turned section as large as feasible and concentric
FIG. 5 Tension Test Specimen for Bolt with Turned-Down Shank for Inch Bolts
F606/F606M − 21
D = nominal thread diameter,
D = diameter of test piece (D < minor diameter of thread),
O O
B = length of thread (B $ D),
L = 5D or (5.65 S ),
O O œ O
L = length of straight portion (L + D ),
C O O
L = total length of test piece (L +2 +B),
T C R
L = length after fracture,
U
S = cross-sectional area, and
O
R = fillet radius (R $ 4mm)
FIG. 6 Tension Specimens with Turned-down Shank for Metric Bolts
FIG. 7 Location of Standard Round 2-in. Gage Length Tension Test Specimen When Turned from Large Size Bolt
with the axis of the bolt or stud. The gage length for measuring the elongation shall be four times the diameter of the specimen.
specimen for inch series and five times the diameter of the specimen for metric series. Fig. 5 and Fig. 6 illustrate an example of
5 1
these small-size specimens. For arbitration purposes, machined test specimens for bolts and studs ⁄8 in. through 1 ⁄4 in. for inch
fasteners and M16 through M30 for metric fasteners shall be machined with the axis of the specimen located midway between the
center and outside surface shown in Fig. 7.
F606/F606M − 21
3.6.1.3 Bolts and studs 1 ⁄8 in. or M33 and larger may have their shanks machined to test specimen with the axis of the specimen
located midway between the center and outside surface of the bolt or stud as shown in Fig. 7 to sizes indicated in Fig. 5 and Fig.
6 for inch and metric fasteners respectively.
3.6.1.4 Machined test specimens shall exhibit tensile strength, yield strength (or yield point), elongation, and reduction of area
equal to or greater than the values of these properties specified for the product size in the applicable product specification when
tested in accordance with this section.
3.6.2 Determination of Tensile Properties:
3.6.2.1 Yield Point—Yield point is the first stress in a material, less than the maximum obtainable stress, at which an increase in
strain occurs without an increase in stress. Yield point is intended for application only for materials that may exhibit the unique
characteristic of showing an increase in strain without an increase in stress. The stress-strain diagram is characterized by a sharp
knee or discontinuity. Determine yield point by one of the following methods:
3.6.2.2 Drop of the Beam or Halt of the Pointer Method—In this method apply an increasing load to the specimen at a uniform
rate. When a lever and poise machine is used, keep the beam in balance by running out the poise at approximately a steady rate.
When the yield point of the material is reached, the increase of the load will stop, but run the poise a trifle beyond the balance
position, and the beam of the machine will drop for a brief but appreciable interval of time. When a machine equipped with a
load-indicating dial is used, there is a halt or hesitation of the load-indicating pointer corresponding to the drop of the beam. Note
the load at the “drop of the beam” or the “halt of the pointer” and record the corresponding stress as the yield point.
3.6.2.3 Autographic Diagram Method—When a sharp-kneed stress-strain diagram is obtained by an autographic recording device,
take the stress corresponding to the top of the knee (Fig. 8), or the stress at which the curve drops as the yield point (Fig. 9).
3.6.2.4 Total Extension Under Load Method—When testing material for yield point and the test specimens may not exhibit a
well-defined disproportionate deformation that characterizes a yield point as measured by the drop of the beam, halt of the pointer,
or autographic diagram methods described in 3.6.2.2 and 3.6.2.3, a value equivalent to the yield point in its practical significance
may be determined by the following method and may be recorded as yield point: Attach a Class C or better extensometer (Note
5 and Note 6) to the specimen. When the load producing a specified extension (Note 7) is reached, record the stress corresponding
to the load as the yield point, and remove the extensometer (Fig. 10).
FIG. 8 Stress-Strain Diagram for Determination of Yield
Strength by the Offset Method
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FIG. 9 Stress-Strain Diagram Showing Yield Point
Corresponding with Top of Knee
FIG. 10 Stress-Strain Diagram Showing Yield Point or Yield Strength by Extension Under Load Method
NOTE 5—Automatic devices are available that determine the load at the specified total extension without plotting a stress-strain curve. Such devices may
be used if their accuracy has been demonstrated. Multiplying calipers and other such devices are acceptable for use provided their accuracy has been
demonstrated as equivalent to a Class C extensometer.
NOTE 6—Reference should be made to Practice E83.
NOTE 7—For steel inch fasteners with a specified yield point not over 80 000 psi, an appropriate value is 0.005 in./in. of gage length. For values above
80 000 psi, this test method is not valid unless the limiting total extension is increased. For steel metric fasteners with a specified yield point not over
550 MPa, an appropriate value is 0.13 mm/mm of gauge length. For values above 550 MPa, this test method is not valid unless the limiting total extension
is increased.
3.6.3 Yield Strength—Yield strength is the stress at which a material exhibits a specified limiting deviation from the proportionality
of stress to strain. The deviation is expressed in terms of strain, percent offset, total extension under load, etc. Determine yield
strength by one of the following methods:
3.6.3.1 Offset Method—To determine the yield strength by the “offset method,” it is necessary to secure data (autographic or
numerical) from which a stress-strain diagram may be drawn. Then on the stress-strain diagram (Fig. 8) lay off om equal to the
F606/F606M − 21
specified value of the offset, draw mn parallel to oA, and thus locate r. The yield strength load R is the load corresponding to the
highest point of the stress-strain curve before or at the intersection of mn with r. In reporting values of yield strength obtained by
this method, the specified value of “offset” used should be stated in parentheses after the term yield strength. For inch fasteners:
Yield strength ~0.2 % offset! 5 52 000 psi (3)
For metric fasteners:
Yield strength 0.2 % offset 5 360 MPa (4)
~ !
In using this method, a minimum extensometer magnification of 250 to 1 is required. A Class B1 extensometer meets this re-
quirement (see Note 6). See also Note 5 for automatic devices.
3.6.3.2 Extension Under Load Method—For tests to determine the acceptance or rejection of material whose stress-strain
characteristics are well known from previous tests of similar material in which stress-strain diagrams were plotted, the total strain
corresponding to the stress at which the specified offset (see Note 8) occurs will be known within satisfactory limits. The stress
on the specimen, when this total strain is reached, is the value of the yield strength. The total strain can be obtained satisfactorily
by use of a Class B1 extensometer (Note 5 and Note 6).
NOTE 8—The appropriate magnitude of the extension under load will obviously vary with the strength range of the particular material under test. In
general, the value of extension under load applicable to any material strength level may be determined from the sum of the proportional strain and the
plastic strain expected at the specified yield strength. The following equation is used:
Extension under load, in./in. of gage length for inch fasteners and mm/mm of gage length for metric fasteners = (YS/E) = r
where:
YS = specified yield strength, psi for inch fasteners and MPa for metric fasteners,
E = modulus of elasticity, psi for inch fasteners and MPa for metric fasteners, and
r = limiting plastic strain, in./in for inch fasteners and mm/mm for metric fasteners.
3.6.4 Tensile Strength—Calculate the tensile strength by dividing the maximum load the specimen sustains during a tension test
by the original cross-sectional area of the specimen.
3.6.5 Elongation:
3.6.5.1 Fit the ends of the fractured specimen together carefully and measure the distance between the gage marks to the nearest
0.01 in. for gage lengths through 2 in. or 0.25 mm through 50 mm gauge length. Measure to the nearest 0.5 % of longer gage
lengths. The elongation is the increase in length of the gage length, expressed as a percentage of the original gage length. In
reporting elongation values, give both the percentage increase and the original gage length.
3.6.5.2 If any part of the fracture takes place outside of the middle half of the gage length or in a punched or scribed mark within
the reduced section, the elongation value obtained may not be representative of the material. If the elongation so measured meets
the minimum requirements specified, no further testing is indicated, but if the elongation is less than the minimum requirements,
discard the test and retest.
3.6.6 Reduction of Area—Fit the ends of the fractured specimen together and measure the mean diameter or the width and
thickness at the smallest cross section to the same accuracy as the original dimensions. The difference between the area thus found
and the area of the original cross section expressed as a percentage of the original area, is the reduction of area.
3.7 Total Extension at Fracture Test:
3.7.1 The extension at fracture (A ) test shall be carried out on stainless steel and nonferrous products (bolts, screws, and studs)
L
in the finished condition, with lengths equal to or in excess of those minimums listed in Table 1 and Table 2.
3.7.2 The products to be tested shall be measured for total length (L ) as described in 3.7.2.1 and shown in Fig. 11.
3.7.2.1 Mark both ends of the bolt, screw, or stud using a permanent marking substance such as bluing so that measuring reference
points for determining total length L and L are established. Using an open-end caliper and steel rule or other device capable of
1 2
measuring to within 0.010 in., or 0.25 mm, determine the total length of the product as shown in Fig. 11.
3.7.3 The product under test shall be screwed into the threaded adapter to a depth of one diameter (see Fig. 2) and load applied
axially until the product fractures. The maximum speed of the free-running cross head shall not exceed 1 in./min for inch fasteners
and 25 mm/min for metric fasteners.
F606/F606M − 21
FIG. 11 Determination of Total Extension at Fracture (A )
L
(only Screw Product Shown)
3.7.4 After the product has been fractured in accordance with 3.7.3, the two broken pieces shall be fitted closely together and the
overall length (L ) measured (see 3.7.2.1 and Fig. 11). The total extension at fracture shall then be calculated as follows:
A = L − L
L 2 1
3.7.5 The value obtained shall equal or exceed the minimum values shown in the applicable specification for the product and
material type.
3.8 Single Shear Test—(Note 9) This test is intended to determine the ability of a fastener to withstand a predetermined load when
applied transversely to the axis of the fastener. Shear is defined as an action or stress caused by applied forces that causes two
adjacent parts of a body to slide on each other to cause separation. Shear tests may be conducted in either tension-type or
compression-type single shear fixture.
3.8.1 The specimen shall be tested using hardened steel plates of sufficient thickness to preclude bearing failure. Holes in the shear
plates shall be ⁄16 in. larger than the nominal body diameter or nominal thread diameter of the test bolt for inch fasteners and 1.5
mm for metric fasteners. The holes shall be chamfered 0.010 in. or 0.25 mm to relieve sharp edges. Shear plates shall be prevented
from separating by means of a suitable jig or by using a nut on the test bolt tightened finger tight.
3.8.2 The test specimen, when assembled in the shear jig, shall be mounted in a tensile-testing machine capable of applying load
at a controllable rate. The grips shall be self-aligning and care shall be taken when mounting the specimen to assure that the load
will be transmitted in a straight line transversely through the test bolt. Load shall be applied and continued until fracture of the
1 1
bolt. Speed of testing as determined with a free-running cross head shall not be less than ⁄4 in. 6.0 mm nor greater than ⁄2 in./min
or 12.0 mm/min.
3.8.3 The maximum load applied to the specimen, coincident with or prior to bolt fracture shall be recorded as the shear strength
of the bolt. At the discretion of the testing activity, tests need not be continued to destruction provided that the specimen supports,
without evidence of bolt fracture, the minimum load specified.
3.8.4 A typical test fixture for tension shear testing is shown in Fig. 12.
NOTE 9—This single-shear test is primarily used for testing Specification A394 tower bolts which range in size from ⁄2 through 1 in. diameter. For general
use, the shear test practices and fixturing found in MIL STD 1312 Test 13 is used for double shear and Test 20 may be used for single shear.
4. Test Methods for Internally Threaded Fasteners
4.1 Product Hardness—For routine inspection of both heat-treated and nonheat-treated nuts, hardness shall be determined on the
bearing face or wrench flats after removal of any oxide, decarburization, plating, or other coating material. Rockwell or Brinell
hardness shall be used at the option of the manufacturer, taking into account the size and grade or property class of the product.
4.1.1 The preparation of test specimens and the performance of hardness tests for Rockwell and Brinell testing shall be in
conformance with the requirements of Test Methods E18 and E10, respectively.
4.1.2 Readings when taken on the bearing face shall be halfway between the major diameter of the thread and one corner. The
F606/F606M − 21
FIG. 12 Typical Single Shear Fixture (Tension Type)
reported hardness shall be the average of two hardness readings located 180° apart. The readings when taken on the wrench flats
shall be one third of the distance from a corner to the center of the wrench face. The reported harness shall be the average of two
readings located from opposite corners.
4.1.3 For the purpose of arbitration or for nuts too large for full size testing, where hardness alone shall determine acceptance (see
4.1.4), the following shall apply.
4.1.3.1 Sample nuts shall be sectioned laterally at approximately one half ( ⁄2) of the nut height. Such samples need not be
threaded, but shall be part of the manufacturing lot that was formed (in the case of heat-treated nuts, formed and heat-treated) with
the product to be shipped. The preparation of the sample shall be in accordance with 4.1.1 above. All readings shall be conducted
on a Rockwell Hardness testing m
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