ASTM A307-21

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.
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Designation: A307 − 14 A307 − 21
Standard Specification for
Carbon Steel Bolts, Studs, and Threaded Rod 60 000 PSI
Tensile Strength
This standard is issued under the fixed designation A307; 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.
ε NOTE—Section 7.3 was editorially corrected in May 2017.
1. Scope*
1.1 This specification covers the chemical and mechanical requirements of two grades of carbon steel bolts and studs in sizes ⁄4
in. through 4 in. The fasteners are designated by “Grade” denoting tensile strength and intended use, as follows:
Grade Description
Grade A Bolts, studs, and threaded
rod having a minimum
tensile strength of 60 ksi
and intended for general
applications,
Grade B Bolts, studs, and threaded
A
rod having a tensile
strength of 60 to 100 ksi and
intended for flanged joints in
piping systems with cast iron
flanges, and
Grade C Replaced by Specification
F1554 Gr.36
A
Threaded rod is not usually produced to Grade B, but can be when specified by the purchaser.
1.2 This specification does not cover requirements for machine screws, thread cutting/forming screws, mechanical expansion
anchors or similar externally threaded fasteners.
1.3 Suitable nuts are covered in Specification A563. Unless otherwise specified, the grade and style of nut for each grade of
fastener, of all surface finishes, shall be as follows:
A
Fastener Grade and Size Nut Grade and Style
1 1
A ⁄4 to 1 ⁄2 in. A, hex
A over 1 ⁄2 to 4 in. A, heavy hex
B, ⁄4 to 4 in. A, heavy hex
This specification is under the jurisdiction of ASTM Committee F16 on Fasteners and is the direct responsibility of Subcommittee F16.02 on Steel Bolts, Nuts, Rivets
and Washers.
Current edition approved Oct. 1, 2014Feb. 15, 2021. Published October 2014April 2021. Originally approved in 1947. Last previous edition approved in 20122014 as
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A307 –12. –14 . DOI: 10.1520/A0307-14E01.10.1520/A0307-21.
For ASME Boiler and Pressure Vessel Code applications see related Specification SA-307 in Section II of that Code.
*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
A307 − 21
A
Nuts of other grades and styles having specified proof load stresses (Specification A563, Table 3) greater than the specified grade and style of nut are also suitable.
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1.4 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
1.5 Supplementary Requirement S1 of an optional nature is provided, which describes additional restrictions to be applied when
bolts are to be welded. It shall apply only when specified in the inquiry, order, and contract.
1.6 Terms used in this specification are defined in Terminology F1789 unless otherwise defined herein.
1.7 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:
A563 Specification for Carbon and Alloy Steel Nuts
A706/A706M Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement
A751 Test Methods and Practices for Chemical Analysis of Steel Products
B695 Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel
F606F606/F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners,
Washers, and Rivets (Metric) F0606_F0606M Direct Tension Indicators, and Rivets
F788/F788MF788 Specification for Surface Discontinuities of Bolts, Screws, Studs, and Rivets, Inch and Metric Series
F1470 Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
F1554 Specification for Anchor Bolts, Steel, 36, 55, and 105-ksi Yield Strength
F1789 Terminology for F16 Mechanical Fasteners
F2329F2329/F2329M Specification for Zinc Coating, Hot-Dip, Requirements for Application to Carbon and Alloy Steel Bolts,
Screws, Washers, Nuts, and Special Threaded Fasteners
2.2 ASME Standards:
B 1.1 Unified Screw Threads
B 18.2.1 Square and Hex Bolts and Screws
B 18.24 Part Identifying Number (PIN) Code System
B 18.5 Round Head Bolts (Inch Series)
B18.31.3 Threaded Rods (Inch Series)
3. Ordering Information
3.1 Orders for externally threaded fasteners (including nuts and accessories) under this specification shall include the following:
3.1.1 ASTM designation and year of issue,
3.1.2 Name of product, bolts or studs; and bolt head style, that is, hex or heavy hex, or threaded rod,
3.1.3 Grade, that is, A, or B. If no grade is specified, Grade A is furnished.
3.1.4 Quantities (number of pieces by size including nuts),
3.1.5 Fastener size and length,
3.1.6 Washers—Quantity and size (separate from bolts),
3.1.7 Zinc Coating—Specify the zinc-coating process required, for example, hot-dip, mechanically deposited, or no preference
(see 4.5).
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, ThreeTwo Park Ave., New York, NY 10016-5990,
http://www.asme.org.
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3.1.8 Other Finishes—Specify other protective finish, if required.
3.1.9 Specify if inspection at point of manufacture is required,
3.1.10 Specify if certified test report is required (see 9.2), and
3.1.11 Specify additional testing (9.3) or special requirements.
3.1.12 For establishment of a part identifying system, see ASME B18.24.
4. Materials and Manufacture
4.1 Steel for bolts, studs, and threaded rod shall be made by the open-hearth, basic-oxygen, or electric-furnace process.
4.2 Bolts shall be produced by hot or cold forging of the heads or machining from bar stock.
4.3 Heat Treatment:
4.3.1 Cold headed fasteners with head configurations other than hex having a specified minimum head height less than or equal
to .50.5 D (D is nominal diameter) shall be stress relief annealed at a minimum temperature of 875°F.875 °F. This would include
cold headed Round Head and Round Head Square Neck Bolts in accordance with ASME B18.5. When specified by the purchaser,
cold headed hex head bolts and screws shall be stress relieved at 875 °F minimum.
4.3.2 Stress relieving of hex head fasteners and those with minimum head heights greater than .50.5 D shall be at the
manufacturer’s option.
4.4 Bolt and stud threads shall be rolled or cut.
4.5 Zinc Coatings, Hot-Dip and Mechanically Deposited:
4.5.1 When zinc-coated fasteners are required, the purchaser shall specify the zinc-coating process, for example hot dip,
mechanically deposited, or no preference.
4.5.2 When hot-dip is specified, the fasteners shall be zinc-coated by the hot-dip process in accordance with the requirements of
Specification F2329F2329/F2329M.
4.5.3 When mechanically deposited is specified, the fasteners shall be zinc-coated by the mechanical-deposition process in
accordance with the requirements of Class 55 of Specification B695.
4.5.4 When no preference is specified, the supplier may furnish either a hot-dip zinc coating in accordance with Specification
F2329F2329/F2329M, or a mechanically deposited zinc coating in accordance with Specification B695, Class 55. Threaded
components (bolts and nuts) shall be coated by the same zinc-coating process and the supplier’s option is limited to one process
per item with no mixed processes in a lot.
5. Chemical Composition
5.1 Grade A and B bolts, studs, and threaded rod shall have a heat analysis conforming to the requirements specified in Table 1
based on the steel producer’s heat analysis.
5.2 The purchaser shall have the option of conducting product analyses on finished bolts in each lot, which shall conform to the
product analysis specified in Table 1.
5.3 In case of conflict or for referee purposes, the product analysis shall take precedence.
5.4 Bolts and studs are customarily furnished from stock, in which case individual heats of steel cannot be identified.
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TABLE 1 Chemical Requirements for Grades A and B Bolts,
Studs, and Threaded Rod
Heat Analysis Product Analysis
Heat Analysis Product Analysis
Carbon, max 0.29 0.33
Manganese, max 1.20 1.25
Phosphorus, max 0.04 0.041
Sulfur, max
A
Grade A 0.15
Grade B 0.05 0.051
A
Resulfurized steel is not subject to rejection based on product analysis for sulfur.
5.5 Application of heats of steel to which bismuth, selenium, tellurium, or lead has been intentionally added shall not be permitted
for Grade B bolts and studs.
5.6 Chemical analyses shall be performed in accordance with Test Methods, Practices, and Terminology A751.
6. Mechanical Properties
6.1 Grades A and B bolts, studs, and threaded rod shall conform to the hardness specified in Table 2.
6.2 Grade A and B bolts, studs, and threaded rod 1½1 ⁄2 in. in diameter or less, other than those excepted in 6.4, shall be tested
full size and shall conform to the requirements for tensile strength specified in Table 3. Threaded rod is permitted to be cut to a
length suitable for tensile testing and shall be treated using the same method specified for studs.
6.3 Grade A and B bolts, studs, and threaded rod larger than 1 ⁄2 in. in diameter, other than those excepted in 6.4, shall preferably
be tested full size and when equipment of sufficient capacity is available and shall conform to the requirements for tensile strength
specified in Table 3. When equipment of sufficient capacity for full-size testing is not available, or when the length of the bolt or
stud makes full-size testing impractical, machined specimens shall be tested and shall conform to the requirements specified in
Table 4.
6.4 Grades A and B bolts and studs less than three diameters in nominal length or bolts with drilled or undersize heads are not
subject to tensile tests.
6.5 In the event that bolts, studs, and threaded rod are tested by both full size and by machine test specimen methods, the full-size
test shall govern if a controversy between the two methods exists.
6.6 For bolts, studs, and threaded rod on which both hardness and tension tests are performed, acceptance based on tensile
requirements shall take precedence in the event that there is controversy over low readings of hardness tests.
TABLE 2 Hardness Requirements for Bolts, Studs, and Threaded
Rod
A
Grade Nominal Hardness
Length, in.
Brinell Rockwell B
min max min max
B
A Less than 3 × dia 121 241 69 100
3 × dia and longer . . . 241 . . . 100
B
B Less than 3 × dia 121 212 69 95
3 × dia and longer . . . 212 . . . 95
A
As measured anywhere on the surface or through the cross section.
B
Also bolts with drilled or undersize heads. These sizes and bolts with modified
heads shall meet the minimum and maximum hardness as hardness is the only
requirement.
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TABLE 3 Tensile Requirements for Full-Size Bolts, Studs, and
Threaded Rod
B
Bolt Threads Stress Tensile Strength, lbf
A
Size, per inch Area,
Grade Grade B
in.
in.
C
A, min
D D
min max
⁄4 20 0.0318 1 900 1 900 3 180
⁄16 18 0.0524 3 100 3 100 5 240
⁄8 16 0.0775 4 650 4 650 7 750
⁄16 14 0.1063 6 350 6 350 10 630
⁄2 13 0.1419 8 500 8 500 14 190
⁄16 12 0.182 11 000 11 000 18 200
⁄8 11 0.226 13 550 13 550 22 600
⁄4 10 0.334 20 050 20 050 33 400
⁄8 9 0.462 27 700 27 700 46 200
1 8 0.606 36 350 36 350 60 600
1 ⁄8 7 0.763 45 800 45 800 76 300
1 ⁄4 7 0.969 58 150 58 150 96 900
1 ⁄8 6 1.155 69 300 69 300 115 500
1 ⁄2 6 1.405 84 3
...