ASTM A574-21

Standard Specification for Alloy Steel Socket-Head Cap Screws

ABSTRACT
This specification covers the requirements for quenched and tempered alloy steel socket-head cap screws. The screws shall be fabricated from steel made to fine grain practice and shall be alloy steel conforming to the chemical composition specified. Different tests shall be conducted in order to determine the following mechanical properties of screws: tensile or wedge strength, proof load, yield strength, elongation, Rockwell hardness, and Vickers hardness.
SCOPE
1.1 This specification covers the requirements for quenched and tempered alloy steel hexagon socket-head cap screws, 0.060 through 4 in. in diameter where high strength is required.  
1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 The following hazard caveat pertains only to the test method portions, Sections 5.1, 5.6, 8, and 12, of this specification. 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.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2021
• ICS: 21.060.10 - Bolts, screws, studs
• Technical Committee: F16 - Fasteners
• Drafting Committee: F16.02 - Steel Bolts, Studs and Nuts

Relations

• Refers: ASTM F1470-24 - Standard Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
• Effective Date: 01-Jan-2024
• Refers: ASTM F1789-23 - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Nov-2023
• Refers: ASTM F2282-23 - Standard Specification for Quality Assurance Requirements for Carbon and Alloy Steel Wire, Rods, and Bars for Mechanical Fasteners
• Effective Date: 01-Nov-2023
• Refers: ASTM F1940-07a(2019) - Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
• Effective Date: 01-Aug-2019
• Refers: ASTM F788-13(2018) - Standard Specification for Surface Discontinuities of Bolts, Screws, and Studs, Inch and Metric Series
• Effective Date: 01-Sep-2018
• Refers: ASTM F2282-18 - Standard Specification for Quality Assurance Requirements for Carbon and Alloy Steel Wire, Rods, and Bars for Mechanical Fasteners
• Effective Date: 01-Sep-2018
• Refers: ASTM F1470-18 - Standard Practice for Fastener Sampling for Specified Mechanical Properties and Performance Inspection
• Effective Date: 01-Feb-2018
• Refers: ASTM F1789-17 - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Jun-2017
• Refers: ASTM F606/F606M-16 - Standard Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets
• Effective Date: 01-Sep-2016
• Refers: ASTM F1789-16 - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Aug-2016
• Refers: ASTM F2282-15 - Standard Specification for Quality Assurance Requirements for Carbon and Alloy Steel Wire, Rods, and Bars for Mechanical Fasteners
• Effective Date: 01-Dec-2015
• Refers: ASTM F2282-03(2015) - Standard Specification for Quality Assurance Requirements for Carbon and Alloy Steel Wire, Rods, and Bars for Mechanical Fasteners
• Effective Date: 01-Jul-2015
• Refers: ASTM F1789-15a - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Mar-2015
• Refers: ASTM F1789-15 - Standard Terminology for F16 Mechanical Fasteners
• Effective Date: 01-Feb-2015
• Refers: ASTM F606/F606M-14a - Standard Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets
• Effective Date: 01-Nov-2014

Overview

ASTM A574-21 specifies requirements for quenched and tempered alloy steel hexagon socket-head cap screws ranging in sizes from 0.060 to 4 inches in diameter. This specification is designed for applications that demand high-strength fasteners. Published and maintained by ASTM International, A574-21 details essential mechanical properties, manufacturing practices, chemical composition, testing methods, and quality assurances necessary for manufacturers, suppliers, and end-users of alloy steel socket-head cap screws.

Key Topics

• Material Requirements: Screws must be produced from alloy steel made using fine grain practice, conforming to chemical composition requirements. The steel must include alloying elements such as chromium, nickel, molybdenum, or vanadium to meet strength properties.
• Heat Treatment: The cap screws are heat treated by quenching in oil and tempering at a minimum of 700°F to ensure specified mechanical properties.
• Mechanical Properties: Socket-head cap screws must meet strict standards for:
  • Tensile or wedge strength
  • Proof load and yield strength
  • Elongation and reduction of area
  • Hardness (Rockwell and Vickers)
• Manufacturing & Threading:
  • Screws are cold or hot headed depending on size and purchaser requirements.
  • Thread rolling or cutting options are dictated by diameter and length.
• Surface Finish & Protective Coating:
  • Standard surfaces are bright (uncoated), thermal black oxide, or chemical black oxide.
  • Additional protective or decorative coatings can be applied upon request, with precautions against hydrogen embrittlement.
• Inspection & Testing:
  • Extensive testing for mechanical properties and surface quality.
  • Inspections can be performed by purchasers’ representatives if specified.
• Marking & Packaging: Screws must be clearly marked for manufacturer identification and packaged for traceability and lot identification.

Applications

ASTM A574-21 alloy steel socket-head cap screws are essential in applications where high strength and durability are critical. Typical uses include:

• Industrial machinery: Fastening critical machine components in manufacturing and assembly lines.
• Automotive and transportation: Use in engine components, suspension systems, and other high-stress zones.
• Aerospace: In airframes, landing gear, and systems requiring proven mechanical performance.
• Construction: Structural steelwork and connections where space is limited and high torque is required.
• Heavy equipment: Mining, agricultural, and specialty vehicles demanding robust fasteners resistant to mechanical and environmental stresses.

Related Standards

To ensure product integrity and interchangeability, ASTM A574-21 references several other industry standards, including:

• ASTM A751: Test methods for chemical analysis of steel products
• ASTM E112: Grain size determination
• ASTM F606/F606M: Mechanical testing of fasteners
• ASTM F788: Surface discontinuity requirements for bolts, screws, and rivets
• ASTM F1470: Fastener sampling procedures
• ASTM F1940: Testing for hydrogen embrittlement in coated fasteners
• ASTM F2282 & F2328: Quality assurance for steel wire and tests for decarburization
• ASME B18.3: Dimensional requirements for cap, shoulder, and set screws
• ASME B18.12 & B18.24: Terminology and part identification numbering for mechanical fasteners

Conclusion

ASTM A574-21 provides a rigorous framework for the manufacturing, testing, and application of alloy steel socket-head cap screws. By adhering to this standard, manufacturers and engineers ensure reliability, interchangeability, and optimal performance in high-strength, safety-critical projects across diverse industries. For further technical guidance, it's essential to consult ASTM A574-21 and related references to maintain compliance and achieve best practices in fastener selection and usage.

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:A574 −21
Standard Specification for
Alloy Steel Socket-Head Cap Screws
This standard is issued under the fixed designation A574; 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* chanical Properties and Performance Inspection
F1789Terminology for F16 Mechanical Fasteners
1.1 This specification covers the requirements for quenched
F1940Test Method for Process Control Verification to
and tempered alloy steel hexagon socket-head cap screws,
Prevent Hydrogen Embrittlement in Plated or Coated
0.060through4in.indiameterwherehighstrengthisrequired.
Fasteners
1.2 Thevaluesstatedininch-poundunitsaretoberegarded
F2282SpecificationforQualityAssuranceRequirementsfor
asstandard.Nootherunitsofmeasurementareincludedinthis
Carbon and Alloy Steel Wire, Rods, and Bars for Me-
standard.
chanical Fasteners
1.3 The following hazard caveat pertains only to the test
F2328Test Method for Determining Decarburization and
method portions, Sections 5.1, 5.6, 8, and 12, of this specifi- Carburization in Hardened and Tempered Threaded Steel
cation. This standard does not purport to address all of the
Bolts, Screws, Studs, and Nuts
safety concerns, if any, associated with its use. It is the
2.2 ASME Standards:
responsibility of the user of this standard to establish appro-
B18.3Socket Cap, Shoulder, and Set Screws
priate safety, health, and environmental practices and deter-
B18.12Glossary of Terms for Mechanical Fasteners
mine the applicability of regulatory limitations prior to use.
B18.24Part Identifying Number (PIN) Code System Stan-
1.4 This international standard was developed in accor-
dard for B18 Fastener Products
dance with internationally recognized principles on standard-
3. Terminology
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1 Definitions of Terms Specific to This Standard—The
mendations issued by the World Trade Organization Technical
definition of terms used in this specification shall be as
Barriers to Trade (TBT) Committee.
specified in Terminology F1789, ASME B18.12, or the appli-
cable referenced standards, unless otherwise defined herein. In
2. Referenced Documents
the event that there are differences for a given term, ASTM
2.1 ASTM Standards:
definitions shall be used.
A751Test Methods and Practices for Chemical Analysis of
4. Ordering Information
Steel Products
E112Test Methods for Determining Average Grain Size
4.1 Orders for socket head cap screws under this specifica-
F606/F606MTest Methods for Determining the Mechanical
tion shall include the following information:
Properties of Externally and Internally Threaded
4.1.1 ASTM designation and year of issue.
Fasteners, Washers, Direct Tension Indicators, and Rivets
4.1.2 Name of the screw (SHCS).
F788Specification for Surface Discontinuities of Bolts,
4.1.3 Quantity (number of pieces by size).
Screws, Studs, and Rivets, Inch and Metric Series
4.1.4 Dimensions, including nominal thread designation,
F1470Practice for Fastener Sampling for Specified Me-
thread pitch, and nominal screw length.
4.2 Orders for socket head cap screws shall include the
1 following optional requirements if specified by the purchaser:
This specification is under the jurisdiction of ASTM Committee F16 on
Fasteners and is the direct responsibility of Subcommittee F16.02 on Steel Bolts, 4.2.1 Inspection at point of manufacture.
Nuts, Rivets and Washers.
4.2.2 Coating, if a protective finish other than those, which
Current edition approved Dec. 1, 2021. Published February 2022. Originally
are described in 5.5 is required, it must be specified (see 5.6).
approved in 1967. Last previous edition approved in 2017 as A574–17. DOI:
10.1520/A0574-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from American Society of Mechanical Engineers (ASME), ASME
Standards volume information, refer to the standard’s Document Summary page on International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
the ASTM website. www.asme.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A574−21
4.2.3 Test reports or certificate of conformance, as required (1) bright uncoated, (2) thermal black oxide, or (3) chemical
(see Section 15). black oxide. Hydrogen embrittlement tests shall not be re-
4.2.4 Additional testing (see 12.1). quired for screws furnished in these conditions.
4.2.5 Special packaging (see 18.1.2).
5.6 Protective Coatings:
4.2.6 Supplementary requirements (see S1).
5.6.1 When a protective finish other than as specified in 5.5
4.2.7 Special requirements.
is required, it shall be specified on the purchase order with the
4.2.8 For establishment of a part identifying system, see
applicable finish specification.
ASME B18.24.
5.6.2 When protective or decorative coatings are applied to
the screws, precautions specified by the coating requirements
5. Materials and Manufacture
to minimize internal hydrogen embrittlement shall be exer-
5.1 The screws shall be fabricated from alloy steel made to
cised. Additional precautions such as the requirements in Test
a fine grain practice. In the event of controversy over grain
Method F1940 and Test Methods F606/F606M shall be by
size, referee tests on finished screws conducted in accordance
agreement with the purchaser.
with Test Methods E112 shall prevail.
6. Chemical Composition
5.2 Screws in sizes through 0.750 in. diameter, and with
lengths through ten times the nominal product size or 6.0
6.1 The screws shall be alloy steel conforming to the
inches, whichever is shorter, shall be cold headed, except that chemical composition specified in Table 2 and the require-
whenspecifiedbythepurchaserthescrewsshallbehotheaded.
mentsinSpecificationF2282.SeeSupplementaryRequirement
Larger sizes and longer lengths shall be cold or hot headed at S1 when additional alloy steel grades are required.
the option of the manufacturer, unless otherwise specified by
6.2 One or more of the following alloying elements:
the purchaser. Screws larger than 1.500 in. nominal diameter
chromium, nickel, molybdenum, or vanadium shall be present
shall be permitted to be machined. Sockets shall be forged or
in sufficient quantity to ensure that the specified strength
machined at the option of the manufacturer.
properties are met after oil quenching and tempering. As a
5.3 Screws in sizes through 0.625 in. diameter, and for
guideforselectingmaterial,analloysteelshouldbecapableof
product lengths through 4 in. shall be roll threaded, unless meeting the specified mechanical requirements if the “as oil
otherwise specified by the purchaser. Larger products shall be quenched” core hardness one diameter from the point is equal
rolled, cut, or ground at the option of the manufacturer. to or exceeds 25 HRC + (55 × carbon content).
5.4 Screws shall be heat treated by quenching in oil from 6.3 When product analyses are made by the purchaser from
above the transformation temperature and then tempered by
finished screws representing each lot, the chemical
reheatingtoatleast700°Ftoachievethemechanicalproperties composition, thus determined, shall conform to the require-
specified in Section 7 and Table 1.
ments prescribed for product analysis in Table 2.
5.4.1 When specified by the purchaser, the minimum tem-
6.4 Steel to which bismuth, selenium, tellurium, or lead has
pering temperature shall be verified by subjecting screws to
been intentionally added shall not be permitted.
680°F for 30 minutes at temperature. The mean cross section
6.5 Chemical analyses shall be performed in accordance
hardness of three readings on the screw before and after
with Test Methods, Practices, and Terminology A751.
retempering shall not differ by more than 2 points hardness
Rockwell C (HRC).
7. Mechanical Properties
5.5 Standard Finishes—Unless otherwise specified, the
7.1 Socket head cap screws shall be tested in accordance
screws shall be furnished with one of the following “standard
with the mechanical testing requirements specified in Table 3,
surfaces as manufactured” at the option of the manufacturer:
and shall meet the mechanical requirements in Table 1, and
either Table 4 or Table 5.
TABLE 1 Mechanical Requirements
NOTE 1—For design purposes only, a minimum yield strength at 2%
>0.5 in. and <
#0.5 in. $1.0 in. offset of 153 ksi may be assumed for bolt diameters less than 1.0 in.
Property 1.0 in.
Nom. Dia. Nom. Dia.
Nom. Dia.
7.2 The screws that are tested for wedge tensile strength
Full-size screws:
shallutilizeawedgeoftheanglespecifiedinTable6underthe
Tensile or wedge tensile 180 170 170
head.Tomeettherequirementsofthewedgetest,theremustbe
strength, min, ksi
Proof load (stress), ksi 140 135 135 a tensile failure in the body or thread section. For the purpose
Product hardness:
Rockwell (HRC) 39–44 37–44 37–44
TABLE 2 Chemical Requirements
Composition, %
Machined test specimen:
AA
Element
Yield strength at 0.2% offset, 153
Heat Product
min., ksi
Analysis Analysis
AA
Tensile strength, min., ksi 170
Carbon, min 0.33 0.31
AA
Elongation in 4D, min. 10%
Phosphorus, max 0.035 0.040
AA
Reduction of area, min. 35%
Sulfur, max 0.040 0.045
A
Alloying elements See 6.2
Not Applicable.
A574−21
TABLE 3 Mechanical Testing Requirements
Test Conducted Using Test Conducted Using
Full Size Product Machined Test Specimen
Tensile Hard- Hard- Decarb/
Product
Yield
Item Nom. Dia. Load, ness, ness,Carburization
Wedge Axial
Length
Proof Strength Tensile % Red.
min, lb max min
Tensile Tensile Elongation
Load at 0.2% Strength of Area
Strength Strength
Offset
AB B B
1 All short { Less than 3D . . . . . . .
lengths
AB B CB
2 <1.0 in. { Over 3D . Z . . . . .
AB B C D D D D D
3 $1.0 in. #270 000 Over 3D . Z X . Y Y Y Y
AB B C D D D D D
4 $1.0 in. >270 000 Over 3D . Z . X Y Y Y Y
A
D denotes nominal diameter of product.
B
Denotes mandatory test.
C
Proof load test denoted Z shall be conducted when purchaser requests the test in inquiry and order.
D
Either all tests denoted by X or all tests denoted by Y shall be performed. In case of arbitration full-size tests, denoted X, shall be decisive.
TABLE 4 Tensile Requirements for Coarse Thread Screws TABLE 5 Tensile Requirements for Fine Thread Screws
Proof Load Proof Load
Screw Tensile Stress (Length Screw Tensile Stress (Length
Threads/ Threads/
Dia (D), Load, Area, Measurement Dia (D), Load, Area, Measurement
in. in.
A 2 B A 2 B
in. min, lbf in. Method), in. min, lbf in. Method)
C C
min, lbf min, lbf
0.073 64 473 0.00263 368 0.060 80 324 0.00180 252
0.086 56 666 0.00370 518 0.073 72 500 0.00278 389
0.099 48 877 0.00487 682 0.086 64 709 0.00394 552
0.112 40 1 090 0.00604 846 0.099 56 941 0.00523 732
0.125 40 1 430 0.00796 1 110 0.112 48 1 190 0.00661 925
0.138 32 1 640 0.00909 1 270 0.125 44 1 490 0.00830 1 160
0.164 32 2 520 0.0140 1 960 0.138 40 1 830 0.01015 1 420
0.190 24 3 150 0.0175 2 450 0.164 36 2 650 0.01474 2 060
0.216 24 4 350 0.0242 3 380 0.190 32 3 600 0.0200 2 800
0.250 20 5 730 0.0318 4 450 0.250 28 6 500 0.0364 5 100
0.3125 18 9 440 0.0524 7 340 0.216 28 4 600 0.0258 3 600
0.375 16 13 900 0.0775 10 800 0.3125 24 10 400 0.0580 8 120
0.4375 14 19 100 0.1063 14 900 0.375 24 15 800 0.0878 12 300
0.500 13 25 500 0.1419 19 900 0.4375 20 21 400 0.1187 16 600
0.5625 12 30 900 0.182 24 600 0.500 20 28 800 0.1599 22 400
0.625 11 38 400 0.226 30 500 0.5625 18 34 500 0.203 27 400
0.750 10 56 800 0.334 45 100 0.625 18 43 500 0.256 34 600
0.875 9 78 500 0.462 62 400 0.750 16 63 400 0.373 50 400
1.000 8 103 000 0.606 81 800 0.875 14 86 500 0.509 68 700
1.125 7 129 000 0.763 103 000 1.000 12 113 000 0.663 89 500
1.250 7 165 000 0.969 131 000 1.125 12 146 000 0.856 116 000
...

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: A574 − 17 A574 − 21
Standard Specification for
Alloy Steel Socket-Head Cap Screws
This standard is issued under the fixed designation A574; 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 This specification covers the requirements for quenched and tempered alloy steel hexagon socket-head cap screws, 0.060
through 4 in. in diameter where high strength is required.
1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 The following hazard caveat pertains only to the test method portions, sectionsSections 5.1, 5.6, 8, and 12, of this
specification. 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 safety, health, and healthenvironmental practices and
determine the applicability of regulatory limitations prior to use.
1.4 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:
A751 Test Methods and Practices for Chemical Analysis of Steel Products
E112 Test Methods for Determining Average Grain Size
F606/F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners,
Washers, Direct Tension Indicators, and Rivets
F788 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
F1789 Terminology for F16 Mechanical Fasteners
F1940 Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
F2282 Specification for Quality Assurance Requirements for Carbon and Alloy Steel Wire, Rods, and Bars for Mechanical
Fasteners
F2328 Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts,
Screws, Studs, and Nuts
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 June 1, 2017Dec. 1, 2021. Published June 2017February 2022. Originally approved in 1967. Last previous edition approved in 20162017 as
A574 – 16.A574 – 17. DOI: 10.1520/A0574-17.10.1520/A0574-21.
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.
*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
A574 − 21
2.2 ASME Standards:
B18.3 Socket Cap, Shoulder, and Set Screws
B18.12 Glossary of Terms for Mechanical Fasteners
B18.24 Part Identifying Number (PIN) Code System Standard for B18 Fastener Products
3. Terminology
3.1 Definitions of Terms Specific to This Standard—The definition of terms used in this specification shall be as specified in
Terminology F1789, ASME B18.12, or the applicable referenced standards, unless otherwise defined herein. In the event that there
are differences for a given term, ASTM definitions shall be used.
4. Ordering Information
4.1 Orders for socket head cap screws under this specification shall include the following information:
4.1.1 ASTM designation and year of issue.
4.1.2 Name of the screw (SHCS).
4.1.3 Quantity (number of pieces by size).
4.1.4 Dimensions, including nominal thread designation, thread pitch, and nominal screw length.
4.2 Orders for socket head cap screws shall include the following optional requirements if specified by the purchaser:
4.2.1 Inspection at point of manufacture.
4.2.2 Coating, if a protective finish other than those, which are described in 5.5 is required, it must be specified (see 5.6).
4.2.3 Test reports or certificate of conformance, as required (see Section 15).
4.2.4 Additional testing (see 12.1).
4.2.5 Special packaging (see 18.1.2).
4.2.6 Supplementary requirements (see S1).
4.2.7 Special requirements.
4.2.8 For establishment of a part identifying system, see ASME B18.24.
5. Materials and Manufacture
5.1 The screws shall be fabricated from alloy steel made to a fine grain practice. In the event of controversy over grain size, referee
tests on finished screws conducted in accordance with Test Methods E112 shall prevail.
5.2 Screws in sizes through 0.750 in. diameter, and with lengths through ten times the nominal product size or 6.0 inches,
whichever is shorter, shall be cold headed, except that when specified by the purchaser the screws shall be hot headed. Larger sizes
and longer lengths shall be cold or hot headed at the option of the manufacturer, unless otherwise specified by the purchaser.
Screws larger than 1.500 in. nominal diameter shall be permitted to be machined. Sockets shall be forged or machined at the option
of the manufacturer.
5.3 Screws in sizes through 0.625 in. diameter, and for product lengths through 4 in. shall be roll threaded, unless otherwise
specified by the purchaser. Larger products shall be rolled, cut, or ground at the option of the manufacturer.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
www.asme.org.
A574 − 21
5.4 Screws shall be heat treated by quenching in oil from above the transformation temperature and then tempered by reheating
to at least 700°F to achieve the mechanical properties specified in Section 7 and Table 1.
5.4.1 When specified by the purchaser, the minimum tempering temperature shall be verified by subjecting screws to 680°F for
30 minutes at temperature. The mean cross section hardness of three readings on the screw before and after retempering shall not
differ by more than 2 points hardness Rockwell C (HRC).
5.5 Standard Finishes—Unless otherwise specified, the screws shall be furnished with one of the following “standard surfaces as
manufactured” at the option of the manufacturer: (1) bright uncoated, (2) thermal black oxide, or (3) chemical black oxide.
Hydrogen embrittlement tests shall not be required for screws furnished in these conditions.
5.6 Protective Coatings:
5.6.1 When a protective finish other than as specified in 5.5 is required, it shall be specified on the purchase order with the
applicable finish specification.
5.6.2 When protective or decorative coatings are applied to the screws, precautions specified by the coating requirements to
minimize internal hydrogen embrittlement shall be exercised. Additional precautions such as the requirements in Test Method
F1940 and Test Methods F606/F606M shall be by agreement with the purchaser.
6. Chemical Composition
6.1 The screws shall be alloy steel conforming to the chemical composition specified in Table 2 and the requirements in
Specification F2282. See Supplementary Requirement S1 when additional alloy steel grades are required.
6.2 One or more of the following alloying elements: chromium, nickel, molybdenum, or vanadium shall be present in sufficient
quantity to ensure that the specified strength properties are met after oil quenching and tempering. As a guide for selecting material,
an alloy steel should be capable of meeting the specified mechanical requirements if the “as oil quenched” core hardness one
diameter from the point is equal to or exceeds 25 HRC + (55 × carbon content).
6.3 When product analyses are made by the purchaser from finished screws representing each lot, the chemical composition, thus
determined, shall conform to the requirements prescribed for product analysis in Table 2.
6.4 Steel to which bismuth, selenium, tellurium, or lead has been intentionally added shall not be permitted.
6.5 Chemical analyses shall be performed in accordance with Test Methods, Practices, and Terminology A751.
TABLE 1 Mechanical Requirements
>0.5 in. and <
#0.5 in. $1.0 in.
Property 1.0 in.
Nom. Dia. Nom. Dia.
Nom. Dia.
Full-size screws:
Tensile or wedge tensile 180 170 170
strength, min, ksi
Proof load (stress), ksi 140 135 135
Product hardness:
Rockwell (HRC) 39–44 37–44 37–44
Machined test specimen:
A A
Yield strength at 0.2% offset, 153
min., ksi
A A
Tensile strength, min., ksi 170
A A
Elongation in 4D, min. 10%
A A
Reduction of area, min. 35%
A
Not Applicable.
A574 − 21
TABLE 2 Chemical Requirements
Composition, %
Element
Heat Product
Analysis Analysis
Carbon, min 0.33 0.31
Phosphorus, max 0.035 0.040
Sulfur, max 0.040 0.045
Alloying elements See 6.2
7. Mechanical Properties
7.1 Socket head cap screws shall be tested in accordance with the mechanical testing requirements specified in Table 3, and shall
meet the mechanical requirements in Table 1, and either Table 4 or Table 5.
NOTE 1—For design purposes only, a minimum yield strength at 2%2 % offset of 153 ksi may be assumed for bolt diameters less than 1.0 in.
7.2 The screws that are tested for wedge tensile strength shall utilize a wedge of the angle specified in Table 6 under the head.
To meet the requirements of the wedge test, there must be a tensile failure in the body or thread section. For the purpose of this
test, failure means separation into two pieces. Screws threaded to the head shall pass the requirements for this test if the fracture
that caused failure originated in the thread area, even though it may have propagated into the fillet area or the head before
separation.
8. Metallurgical Requirement
8.1 Carburization or Decarburization:
8.1.1 There shall be no evidence of carburization or total decarburization on the surfaces of the heat-treated screws when measured
in accordance with Test Method F2328 (Class 3 Product).
8.1.2 The depth of partial decarburization shall be limited to the values in Test Method F2328 (Class 3 Product) when measured
as described therein.
9. Dimensions
9.1 Unless otherwise specified, the product shall conform to the requirements of ASME B18.3.
10. Workmanship, Finish, and Appearance
10.1 Surface Discontinuities—The surface discontinuities for these products shall conform to Specification F788 and the
additional limitations specified herein.
TABLE 3 Mechanical Testing Requirements
Test Conducted Using Test Conducted Using
Full Size Product Machined Test Specimen
Tensile Hard- Hard- Decarb/
Product
Yield
Item Nom. Dia. Load, ness, ness,Carburization
Wedge Axial
Length
Proof Strength Tensile % Red.
min, lb max min
Tensile Tensile Elongation
Load at 0.2% Strength of Area
Strength Strength
Offset
A B B B
1 All short { Less than 3D . . . . . . .
lengths
A B B C B
2 <1.0 in. { Over 3D . Z . . . . .
A B B C D D D D D
3 $1.0 in. #270,000 Over 3D . Z X . Y Y Y Y
A B B C D D D D D
3 $1.0 in. #270 000 Over 3D . Z X . Y Y Y Y
A B B C D D D D D
4 $1.0 in. >270,000 Over 3D . Z . X Y Y Y Y
A B B C D D D D D
4 $1.0 in. >270 000 Over 3D . Z . X Y Y Y Y
A
D denotes nominal diameter of product.
B
Denotes mandatory test.
C
Proof load test denoted Z shall be conducted when purchaser requests the test in inquiry and order.
D
Either all tests denoted by X or all tests denoted by Y shall be performed. In case of arbitration full-size tests, denoted X, shall be decisive.
A574 − 21
TABLE 4 Tensile Requirements for Coarse Thread Screws
Proof Load
Screw Tensile Stress (Length
Threads/
Dia (D), Load, Area, Measurement
in.
A 2 B
in. min, lbf in. Method),
C
min, lbf
0.073 64 473 0.00263 368
0.086 56 666 0.00370 518
0.099 48 877 0.00487 682
0.112 40 1 090 0.00604 846
0.125 40 1 430 0.00796 1 110
0.138 32 1 640 0.00909 1 270
0.164 32 2 520 0.0140 1 960
0.190 24 3 150 0.0175 2 450
0.216 24 4 350 0.0242 3 380
0.250 20 5 730 0.0318 4 450
0.3125 18 9 440 0.0524 7 340
0.375 16 13 900 0.0775 10 800
0.4375 14 19 100 0.1063 14 900
0.500 13 25 500 0.1419 19 900
0.5625 12 30 900 0.182 24 600
0.625 11 38 400 0.226 30 500
0.750 10 56 800 0.334 45 100
0.875 9 78 500 0.462 62 400
1.0
...