ASTM A921/A921M-93(2022)
(Specification)Standard Specification for Steel Bars, Microalloy, Hot-Wrought, Special Quality, for Subsequent Hot Forging
Standard Specification for Steel Bars, Microalloy, Hot-Wrought, Special Quality, for Subsequent Hot Forging
ABSTRACT
This specification covers hot-wrought, special quality microalloyed carbon steel bars intended for use as hot forging stock. The bars shall be hot-wrought, as-wrought, unless thermal treatment is necessary to ensure cold shearability. The steel specimens shall be killed and shall conform to the fine grain size requirement. Heat analysis and product analysis shall be performed wherein the specimens shall conform to the required chemical compositions of vanadium, columbium, and molybdenum.
SCOPE
1.1 This specification covers hot-wrought, special quality microalloyed carbon steel bars intended for use as hot forging stock. The bars shall be hot-wrought, as-wrought, unless thermal treatment is necessary to ensure cold shearability.
1.2 The bars shall be furnished to chemical composition only. Chemical composition is based on standard carbon steel grades modified to include microalloying elements such as columbium (niobium), vanadium, or molybdenum. Desired mechanical properties are developed in the subsequent hot forging and controlled cooling operations.
1.3 Sections and sizes of bar steel available are covered in Specification A29/A29M.
1.4 Supplementary Requirements S1 to S6 are provided for use when additional controls or requirements are desired. These shall apply only when specified on the purchase order.
1.5 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text and tables, 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.
1.6 Unless the order specifies the applicable “M” specification designation, the material shall be furnished to the inch-pound units.
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.
General Information
Relations
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:A921/A921M −93 (Reapproved 2022)
Standard Specification for
Steel Bars, Microalloy, Hot-Wrought, Special Quality, for
Subsequent Hot Forging
This standard is issued under the fixed designationA921/A921M; 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.
1. Scope 2. Referenced Documents
1.1 This specification covers hot-wrought, special quality 2.1 ASTM Standards:
microalloyed carbon steel bars intended for use as hot forging
A29/A29M SpecificationforGeneralRequirementsforSteel
stock. The bars shall be hot-wrought, as-wrought, unless
Bars, Carbon and Alloy, Hot-Wrought
thermal treatment is necessary to ensure cold shearability.
A576 Specification for Steel Bars, Carbon, Hot-Wrought,
Special Quality
1.2 The bars shall be furnished to chemical composition
A788/A788M Specification for Steel Forgings, General Re-
only. Chemical composition is based on standard carbon steel
quirements
grades modified to include microalloying elements such as
E45 Test Methods for Determining the Inclusion Content of
columbium (niobium), vanadium, or molybdenum. Desired
Steel
mechanical properties are developed in the subsequent hot
forging and controlled cooling operations.
3. Terminology
1.3 Sections and sizes of bar steel available are covered in
3.1 Definitions of Terms Specific to This Standard:
Specification A29/A29M.
3.1.1 microalloyed steels—microalloyed steels are carbon
1.4 Supplementary Requirements S1 to S6 are provided for
steels to which small quantities of certain elements are added
use when additional controls or requirements are desired.
in order to enhance mechanical properties. This enhancement
These shall apply only when specified on the purchase order.
of mechanical properties results from control of the tempera-
1.5 The values stated in either inch-pound units or SI units
ture and cooling rate during the final hot-working process.
are to be regarded separately as standard. Within the text and
tables,SIunitsareshowninbrackets.Thevaluesstatedineach
4. Ordering Information
system are not necessarily exact equivalents; therefore, to
4.1 Orders for material supplied to this specification should
ensure conformance with the standard, each system shall be
include the following, as required, to describe adequately the
used independently of the other, and values from the two
desired material:
systems shall not be combined.
4.1.1 Quantity (weight or number of bars),
1.6 Unless the order specifies the applicable “M” specifica-
4.1.2 Name of material (hot-rolled microalloyed steel bars),
tion designation, the material shall be furnished to the inch-
4.1.3 Dimensions,
pound units.
4.1.4 ASTM specification number and date of issue,
1.7 This international standard was developed in accor-
4.1.5 Gradedesignationorchemicalcompositionlimits(see
dance with internationally recognized principles on standard-
8.1 – 8.5),
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.1.6 Type (see 7.1) to designate grain refiner,
mendations issued by the World Trade Organization Technical
4.1.7 Additions to the specification and Supplementary
Barriers to Trade (TBT) Committee.
Requirements, if required, and,
4.1.8 End use.
This specification is under the jurisdiction ofASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.15 on Bars. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 1, 2022. Published April 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1993. Last previous edition approved in 2016 as A921/ Standards volume information, refer to the standard’s Document Summary page on
A921M – 93(2016). DOI: 10.1520/A0921_A0921M-93R22. the ASTM website.
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A921/A921M−93 (2022)
or tellurium may also be specified by agreement.
5. General Requirements
8.2 Silicon analysis shall be 0.15/0.35 %. Silicon content up
5.1 Material furnished under this specification shall con-
to 0.80 % maximum may be furnished by agreement between
form to the applicable requirements of the current edition of
purchaser and producer.
Specification A29/A29M, unless otherwise provided in this
specification.
8.3 Vanadium, columbium (niobium), or molybdenum may
be specified singly or in combination, subject to the limits
6. Materials and Manufacture
shown in Table 2. The elements and ranges specified shall be
6.1 Melting Practice—The steel shall be produced in accor-
by agreement between the purchaser and the producer.
dance with the applicable methods for primary and secondary
8.4 Titanium may be added for refinement of the austenitic
melting outlined in Specification A788/A788M.
and the as-forged ferritic grain size, or as a precipitation
6.2 The steel shall be killed. Supplementary Requirements
strengthener. When titanium is specified, the titanium limits
S1 through S6 may be invoked upon agreement between
shall be as agreed upon between producer and purchaser. The
producer and purchaser.
titanium analysis shall be reported.
6.3 The bars shall be special quality.
8.5 Nitrogenmaybespecifiedasasupplementtovanadium,
columbium, or titanium. When nitrogen is specified
...
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