ASTM A668/A668M-23

Standard Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use

ABSTRACT
This specification deals with the standard requirements for untreated and heat-treated carbon and alloy steel forgings for general industrial use. This specification covers six classes of carbon steels (Class A to F) and seven classes of alloy steels (Class G, H, and J to N). Materials shall be forged by hot mechanical work. Except for Class A, all forgings shall be heat treated, depending on class, by the following techniques: annealed, or normalized, or normalized and tempered (Classes B, C, D, and G); normalized and tempered, or double-normalized and tempered (Class E); quenched and tempered, or normalized, quenched, and tempered (Classes F); normalized and tempered (Class H); normalized and tempered, or normalized, quenched, and tempered (Class J); and normalized, quenched, and tempered (Classes K, L, M, and N). Steel specimens shall undergo heat and product analyses, and shall conform to required chemical compositions for manganese, phosphorus, and sulfur. Steel forgings shall also be tested on their conformance to the following tensile requirements: tensile strength, yield point, yield strength, elongation, reduction of area, and Brinell hardness.
SCOPE
1.1 This specification covers untreated and heat-treated carbon and alloy steel forgings for general industrial use. Other ASTM specifications for forgings are available for specific applications such as pressure vessels, railroad use, turbine generators, gearing, and others involving special temperature requirements.  
1.2 Hot-rolled or cold finished bars are not within the scope of this specification.  
1.3 Six classes of carbon steel and seven classes of alloy steel forgings are listed (see Section 7), which indicate their required heat treatments, as well as mechanical properties.  
1.4 Provision, with the suffix H for certification and marking, for the supply of forgings after hardness testing only.  
1.5 Supplementary requirements, including those in Specification A788/A788M, of an optional nature are provided. These shall apply only when specified by the purchaser.  
1.6 Appendix X1 lists the current classes corresponding to the various classes of Specifications A235, A237, and A243, which have been superseded by this specification.  
1.7 The values stated in either SI units or inch-pound units are to be regarded separately as standard; within the text and tables, the SI units are shown in brackets. 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.  
1.8 Unless the order specifies the applicable “M” specification, the forgings shall be furnished to the inch-pound units.  
1.9 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-Apr-2023
• ICS: 77.140.85 - Iron and steel forgings
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.06 - Steel Forgings and Billets

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: A668/A668M − 23 American Association State
Highway and Transportation Officials Standard
AASHTO No.: M 102M/M 102
Standard Specification for
Steel Forgings, Carbon and Alloy, for General Industrial
1
Use
This standard is issued under the fixed designation A668/A668M; 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* 1.9 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This specification covers untreated and heat-treated
ization established in the Decision on Principles for the
carbon and alloy steel forgings for general industrial use. Other
Development of International Standards, Guides and Recom-
ASTM specifications for forgings are available for specific
mendations issued by the World Trade Organization Technical
applications such as pressure vessels, railroad use, turbine
Barriers to Trade (TBT) Committee.
generators, gearing, and others involving special temperature
requirements.
2. Referenced Documents
1.2 Hot-rolled or cold finished bars are not within the scope
2
2.1 ASTM Standards:
of this specification.
A275/A275M Practice for Magnetic Particle Examination of
1.3 Six classes of carbon steel and seven classes of alloy
Steel Forgings
steel forgings are listed (see Section 7), which indicate their
A370 Test Methods and Definitions for Mechanical Testing
required heat treatments, as well as mechanical properties.
of Steel Products
A388/A388M Practice for Ultrasonic Examination of Steel
1.4 Provision, with the suffix H for certification and
Forgings
marking, for the supply of forgings after hardness testing only.
A788/A788M Specification for Steel Forgings, General Re-
1.5 Supplementary requirements, including those in Speci-
quirements
fication A788/A788M, of an optional nature are provided.
E290 Test Methods for Bend Testing of Material for Ductil-
These shall apply only when specified by the purchaser.
ity
1.6 Appendix X1 lists the current classes corresponding to
E340 Practice for Macroetching Metals and Alloys
the various classes of Specifications A235, A237, and A243,
which have been superseded by this specification.
3. Terminology
1.7 The values stated in either SI units or inch-pound units
3.1 The terminology section of Specification A788/A788M
are to be regarded separately as standard; within the text and
is applicable to this specification.
tables, the SI units are shown in brackets. The values stated in
3.2 Definitions of Terms Specific to This Standard:
each system are not necessarily exact equivalents; therefore, to
3.2.1 class, n—a description of steel forgings based on heat
ensure conformance with the standard, each system shall be
treatment, mechanical properties and composition.
used independently of the other, and values from the two
3.2.2 controlling cross section thickness (T ), n—the diam-
C
systems shall not be combined.
eter of the largest theoretical sphere which can be inscribed
1.8 Unless the order specifies the applicable “M”
within the volume of the forging.
specification, the forgings shall be furnished to the inch-pound
3.2.3 rough machining, n—machining performed after the
units.
heat treatment cycle used to obtain the stated mechanical
property requirements of Table 2.
1
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
2
A01.06 on Steel Forgings and Billets. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2023. Published May 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1972. Last previous edition approved in 2022 as A668/A668M – 22. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/A0668_A0668M-23. 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
1

---------------------- Page: 1 ----------------------
A668/A668M − 23
3.2.3.1 Discussion—Rough machining is performed by the 6.4 Product Analysis—An analysis may be made by the
forging supplier or forging supplier representative. It does not purchaser according to the requirements of Specificati
...

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: A668/A668M − 22 A668/A668M − 23 American Association State
Highway and Transportation Officials Standard
AASHTO No.: M 102M/M 102
Standard Specification for
Steel Forgings, Carbon and Alloy, for General Industrial
1
Use
This standard is issued under the fixed designation A668/A668M; 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 untreated and heat-treated carbon and alloy steel forgings for general industrial use. Other ASTM
specifications for forgings are available for specific applications such as pressure vessels, railroad use, turbine generators, gearing,
and others involving special temperature requirements.
1.2 Hot-rolled or cold finished bars are not within the scope of this specification.
1.3 Six classes of carbon steel and seven classes of alloy steel forgings are listed (see Section 7), which indicatesindicate their
required heat treatments, as well as mechanical properties.
1.4 Provision, with the suffix H for certification and marking, for the supply of forgings after hardness testing only.
1.5 Supplementary requirements, including those in Specification A788/A788M, of an optional nature are provided. These shall
apply only when specified by the purchaser.
1.6 Appendix X1 lists the current classes corresponding to the various classes of Specifications A235, A237, and A243, which
have been superseded by this specification.
1.7 The values stated in either SI units or inch-pound units are to be regarded separately as standard; within the text and tables,
the SI units are shown in brackets. 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.
1.8 Unless the order specifies the applicable “M” specification, the forgings shall be furnished to the inch-pound units.
1.9 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.
1
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06
on Steel Forgings and Billets.
Current edition approved May 15, 2022May 1, 2023. Published May 2022May 2023. Originally approved in 1972. Last previous edition approved in 20212022 as
A668/A668MA668/A668M – 22.-21a. DOI: 10.1520/A0668_A0668M-22.10.1520/A0668_A0668M-23.
*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
1

---------------------- Page: 1 ----------------------
A668/A668M − 23
2. Referenced Documents
2
2.1 ASTM Standards:
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A788/A788M Specification for Steel Forgings, General Requirements
E290 Test Methods for Bend Testing of Material for Ductility
E340 Practice for Macroetching Metals and Alloys
3. Terminology
3.1 The terminology section of Specification A788/A788M is applicable to this specification.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 class, class—n—a description of steel forgings based on heat treatment, mechanical properties and composition.
3.2.2 controlling cross section thickness (T )—), n—the diameter of the largest theoretical sphere which can be inscribed within
C
the volume of the forging.
3.2.3 rough machining, n—machining performed after the heat treatment cycle used to obtain the stated mechanical property
requirements of Table 2.
3.2.3.1 Discussion—
Rough machining is performed by the forging supplier or forging supplier representative. It does not include machining used to
create detailed features such as gear teeth, splines, threads, or keyways and typically does not produce the surface fini
...