ASTM A304-20

Standard Specification for Carbon and Alloy Steel Bars Subject to End-Quench Hardenability Requirements

ABSTRACT
This specification covers carbon and alloy steel bars subject to end-quench hardenability requirements. The methods for estimating the hardness value of the material are presented. Method A is the minimum and maximum hardness values at any desired distance, Method B is the minimum and maximum distances at which any desired hardness value occurs, Method C is the two maximum hardness values at two desired distances, Method D is the two minimum hardness values at two desired distances, and Method E is any minimum hardness plus any maximum hardness. The heat analysis shall conform to the requirements as to chemical composition. The fine austenitic grain size requirements of the steel material are presented in details. The end-quench hardenability shall conform to the requirements specified on the purchase order. The test specimen requirements indicates that, the number and location of test specimens shall be in accordance with the manufacturers standard practice and shall adequately represent the hardenability of each heat, also, all forged or rolled hardenability test specimens must be normalized prior to testing. The grain size and end-quench hardenability test methods are presented in details.
SCOPE
1.1 This specification covers hot-worked alloy, carbon, and carbon-boron steels in a variety of compositions and sizes, which may attain specified depth of hardening in the end quench test. These steel compositions are identified by the suffix letter “H” added to the conventional grade number.  
1.2 This specification provides for analyses other than those listed under Tables 1 and 2. Special hardenability limits are also permissible when approved by the purchaser and manufacturer.    
1.3 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.  
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-Jun-2020
• ICS: 77.140.60 - Steel bars and rods
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.15 - Bars

Relations

• Refers: ASTM A108-24 - Standard Specification for Steel Bar, Carbon and Alloy, Cold-Finished
• Effective Date: 01-Mar-2024
• Refers: ASTM A108-18 - Standard Specification for Steel Bar, Carbon and Alloy, Cold-Finished
• Effective Date: 01-Nov-2018
• Refers: ASTM A255-10(2018) - Standard Test Methods for Determining Hardenability of Steel
• Effective Date: 01-Sep-2018
• Refers: ASTM A29/A29M-15 - Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
• Effective Date: 01-Nov-2015
• Refers: ASTM A255-10(2014) - Standard Test Methods for Determining Hardenability of Steel
• Effective Date: 01-Oct-2014
• Refers: ASTM A108-13 - Standard Specification for Steel Bar, Carbon and Alloy, Cold-Finished
• Effective Date: 15-Aug-2013
• Refers: ASTM E112-12 - Standard Test Methods for Determining Average Grain Size
• Effective Date: 15-Nov-2012
• Refers: ASTM A29/A29M-12 - Standard Specification for Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements for
• Effective Date: 01-May-2012
• Refers: ASTM A29/A29M-12e1 - Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
• Effective Date: 01-May-2012
• Refers: ASTM A29/A29M-11a - Standard Specification for Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements for
• Effective Date: 01-Oct-2011
• Refers: ASTM A29/A29M-11 - Standard Specification for Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements for
• Effective Date: 01-Apr-2011
• Refers: ASTM E112-10 - Standard Test Methods for Determining Average Grain Size
• Effective Date: 01-Nov-2010
• Refers: ASTM A255-10 - Standard Test Methods for Determining Hardenability of Steel
• Effective Date: 01-May-2010
• Refers: ASTM A108-07 - Standard Specification for Steel Bar, Carbon and Alloy, Cold-Finished
• Effective Date: 01-Sep-2007
• Refers: ASTM A255-07 - Standard Test Methods for Determining Hardenability of Steel
• Effective Date: 01-Sep-2007

Overview

ASTM A304-20 is the international standard specification developed by ASTM for carbon and alloy steel bars that are subject to end-quench hardenability requirements. This specification applies to hot-worked alloy, carbon, and carbon-boron steel bars produced in various compositions and sizes. These steel bars are identified by the suffix “H” added to the grade number, which denotes their hardenability classification. ASTM A304-20 outlines the procedures for determining the hardenability of steel bars, chemical composition requirements, grain size standards, and acceptable test methods for conformity.

By offering a standardized approach to measuring and verifying hardenability, ASTM A304-20 enables manufacturers and end users to reliably specify, source, and use steel bars suited to critical heat treatment applications.

Key Topics

• Steel Bar Types and Compositions
  The standard covers hot-worked carbon, carbon-boron, and alloy steel bars available in a wide range of grades and chemical compositions. Each grade's chemical composition must comply with the detailed requirements specified in Tables 1 (Alloy H-Steels) and 2 (Carbon H-Steels).

• End-Quench Hardenability Testing
  Hardenability is assessed using the end-quench (Jominy) test. The specification provides multiple methods (A through E) for designating hardenability values:

  • Method A: Hardness values at a specific distance from the quenched end
  • Method B: Distances at which a desired hardness value occurs
  • Methods C, D, E: Combinations of minimum or maximum hardness values at designated distances

• Specification and Ordering Requirements
  The standard details the necessary information for placing an order, including quantity, grade, size, cross-sectional shape, length, and hardenability requirements. Special requirements such as custom analyses, straightness, and reporting of heat analysis can also be specified.

• Quality and Test Requirements

  • Chemical analysis must strictly follow requirements
  • Austenitic grain size must meet fine grain standards per ASTM A29/A29M
  • Hardenability test specimens must be normalized prior to testing (if forged or rolled)
  • Conformity is determined using recognized ASTM test methods (e.g., ASTM A255 for hardenability, ASTM E112 for grain size)

Applications

• Automotive and Transportation
  Steel bars conforming to ASTM A304-20 are widely used in automotive components such as gears, shafts, and axles, where precise hardenability is crucial for ensuring strength and wear resistance after heat treatment.

• Machinery Manufacturing
  Applications where reliable and uniform hardening through the steel bar cross-section is required, such as in drive components, lifting equipment, and machinery structural parts.

• Energy and Heavy Equipment
  Suitable for parts exposed to variable stress and requiring uniform mechanical properties after heat treatment, such as wind turbine components, power generation shafts, and mining equipment.

• General Engineering
  Crucial for the manufacture of high-performance fasteners, pins, connectors, and custom-engineered steel components where predictable hardenability is needed.

Related Standards

ASTM A304-20 references and works alongside several other important industry standards:

• ASTM A29/A29M - General requirements for hot-wrought carbon and alloy steel bars
• ASTM A108 - Specification for cold-finished carbon and alloy steel bars
• ASTM A255 - Test methods for determining hardenability of steel (end-quench/Jominy test)
• ASTM E112 - Test methods for determining average grain size
• ASTM E527 - Practice for numbering metals and alloys in the Unified Numbering System (UNS)
• SAE J1086 - Numbering system standard for metals and alloys

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ASTM A304-20 ensures that producers and users across industries can count on consistent, measured, and reliable hardenability performance in carbon and alloy steel bars, supporting the requirements of modern engineering and heat treatment processes.

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: A304 −20
Standard Specification for
Carbon and Alloy Steel Bars Subject to End-Quench
Hardenability Requirements
This standard is issued under the fixed designation A304; 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* E527 Practice for Numbering Metals and Alloys in the
Unified Numbering System (UNS)
1.1 This specification covers hot-worked alloy, carbon, and
2.2 Society of Automotive Engineers (SAE) Standard:
carbon-boron steels in a variety of compositions and sizes,
J 1086 Numbering Metals and Alloys
which may attain specified depth of hardening in the end
quench test. These steel compositions are identified by the
3. Terminology
suffix letter “H” added to the conventional grade number.
3.1 Definitions of Terms Specific to This Standard:
1.2 This specification provides for analyses other than those
3.1.1 hardenability—the relative ability of a steel to harden
listed under Tables 1 and 2. Special hardenability limits are
under heat treatment becomes apparent in the degree to which
also permissible when approved by the purchaser and manu-
the material hardens when quenched at different cooling rates.
facturer.
It is measured quantitatively, usually by noting the extent or
depth of hardening of a standard size and shape test specimen
1.3 The values stated in inch-pound units are to be regarded
in a standardized quench. In the “end-quench” test the “depth
as standard. No other units of measurement are included in this
of hardening” is the distance along the specimen from the
standard.
quenched end to a given hardness.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Ordering Information
ization established in the Decision on Principles for the
4.1 Orders for material under this specification should
Development of International Standards, Guides and Recom-
include the following information, in proper sequence:
mendations issued by the World Trade Organization Technical
4.1.1 Quantity (weight);
Barriers to Trade (TBT) Committee.
4.1.2 Name of material (alloy, carbon, or carbon-boron
steel);
2. Referenced Documents
4.1.3 Cross-sectional shape;
2.1 ASTM Standards:
4.1.4 Size;
A29/A29M SpecificationforGeneralRequirementsforSteel
4.1.5 Length;
Bars, Carbon and Alloy, Hot-Wrought
4.1.6 Grade;
A108 Specification for Steel Bar, Carbon and Alloy, Cold-
4.1.7 End-quenched hardenability (see Section 9);
Finished
4.1.8 Report of heat analysis, if desired (see Section 7);
A255 Test Methods for Determining Hardenability of Steel
4.1.9 Special straightness, if required;
E112 Test Methods for Determining Average Grain Size
4.1.10 ASTM designation and date of issue;
4.1.11 End use or special requirements; and
4.1.12 Leaded steel, when required.
This specification is under the jurisdiction ofASTM Committee A01 on Steel,
NOTE 1—A typical ordering description is as follows: 10 000 lb, alloy
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
bars, round, 4.0 in. dia by 10 ft, Grade 1340H, J 40⁄56 = ⁄16 in., heat
A01.15 on Bars.
analysis required, ASTM A304, dated ________, worm gear.
Current edition approved July 1, 2020. Published July 2020. Originally approved
in 1947. Last previous edition approved in 2016 as A304 – 16. DOI: 10.1520/
4.2 The purchaser shall specify the desired grade, including
A0304-20.
the suffix letter “H,” in accordance with Table 1 or Table 2.
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’ Document Summary page on
Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
the ASTM website.
PA 15096, http://www.sae.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
A304 − 20
A
TABLE 1 Chemical Requirements of Alloy H Steels
NOTE 1—Phosphorus and sulfur designated by the prefix letter “E” is 0.025 %, max.
NOTE 2—Small quantities of certain elements are present in alloy steels that are not specified or required. These elements are considered as incidental
and may be present to the following maximum amounts: copper, 0.35 %; nickel, 0.25 %; chromium, 0.20 %; molybdenum, 0.06 %.
NOTE3—ChemicalrangesandlimitsshowninthistablearesubjecttothepermissiblevariationforproductanalysisshowninSpecificationA29/A29M.
NOTE 4—Standard “H” Steels can be produced with a lead range of 0.15 to 0.35 %. Such steels are identified by inserting the letter “L” between the
second and third numerals of the grade designation, for example, 41L40 H. Lead is generally reported as a range of 0.15 to 0.35 %.
B
Chemical Composition, %
UNS Grade
A
Designation Designation
Carbon Manganese Phosphorus Sulfur Silicon Nickel Chromium Molybdenum
H 13300 1330 H 0.27–0.33 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 13350 1335 H 0.32–0.38 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 13400 1340 H 0.37–0.44 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 13450 1345 H 0.42–0.49 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 40270 4027 H 0.24–0.30 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40280 4028 H 0.24–0.30 0.60–1.00 0.035 0.035–0.050 0.15–0.35 . . 0.20–0.30
H 40320 4032 H 0.29–0.35 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40370 4037 H 0.34–0.41 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40420 4042 H 0.39–0.46 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40470 4047 H 0.44–0.51 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 41180 4118 H 0.17–0.23 0.60–1.00 0.035 0.040 0.15–0.35 . 0.30–0.70 0.08–0.15
H 41300 4130 H 0.27–0.33 0.30–0.70 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41350 4135 H 0.32–0.38 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41370 4137 H 0.34–0.41 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41400 4140 H 0.37–0.44 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41420 4142 H 0.39–0.46 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41450 4145 H 0.42–0.49 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41470 4147 H 0.44–0.51 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41500 4150 H 0.47–0.54 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41610 4161 H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.65–0.95 0.25–0.35
H 43200 4320 H 0.17–0.23 0.40–0.70 0.035 0.040 0.15–0.35 1.55–2.00 0.35–0.65 0.20–0.30
H 43400 4340 H 0.37–0.44 0.55–0.90 0.035 0.040 0.15–0.35 1.55–2.00 0.65–0.95 0.20–0.30
H 43406 E4340 H 0.37–0.44 0.60–0.95 0.035 0.040 0.15–0.35 1.55–2.00 0.65–0.95 0.20–0.30
H 44190 4419 H 0.17–0.23 0.35–0.75 0.035 0.040 0.15–0.35 . . 0.45–0.60
H 46200 4620 H 0.17–0.23 0.35–0.75 0.035 0.040 0.15–0.35 1.55–2.00 . 0.20–0.30
H 46210 4621 H 0.17–0.23 0.60–1.00 0.035 0.040 0.15–0.35 1.55–2.00 . 0.20–0.30
H 46260 4626 H 0.23–0.29 0.40–0.70 0.035 0.040 0.15–0.35 0.65–1.05 . 0.15–0.25
H 47180 4718 H 0.15–0.21 0.60–0.95 0.035 0.040 0.15–0.35 0.85–1.25 0.30–0.60 0.30–0.40
H 47200 4720 H 0.17–0.23 0.45–0.75 0.035 0.040 0.15–0.35 0.85–1.25 0.30–0.60 0.15–0.25
H 48150 4815 H 0.12–0.18 0.30–0.70 0.035 0.040 0.15–0.35 3.20–3.80 . 0.20–0.30
H 48170 4817 H 0.14–0.20 0.30–0.70 0.035 0.040 0.15–0.35 3.20–3.80 . 0.20–0.30
H 48200 4820 H 0.17–0.23 0.40–0.80 0.035 0.040 0.15–0.35 3.20–3.80 . 0.20–0.30
C
H 50401 50B40 H 0.37–0.44 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
C
H 50441 50B44 H 0.42–0.49 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
H 50460 5046 H 0.43–0.50 0.65–1.10 0.035 0.040 0.15–0.35 . 0.13–0.43 .
C
H 50461 50B46 H 0.43–0.50 0.65–1.10 0.035 0.040 0.15–0.35 . 0.13–0.43 .
C
H 50501 50B50 H 0.47–0.54 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
C
H 50601 50B60 H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
H 51200 5120 H 0.17–0.23 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51300 5130 H 0.27–0.33 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 .
H 51320 5132 H 0.29–0.35 0.50–0.90 0.035 0.040 0.15–0.35 . 0.65–1.10 .
H 51350 5135 H 0.32–0.38 0.50–0.90 0.035 0.040 0.15–0.35 . 0.70–1.15 .
H 51400 5140 H 0.37–0.44 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51450 5145 H 0.42–0.49 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51470 5147 H 0.45–0.52 0.60–1.05 0.035 0.040 0.15–0.35 . 0.80–1.25 .
H 51500 5150 H 0.47–0.54 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51550 5155 H 0.50–0.60 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51600 5160 H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.60–1.00 .
C
H 51601 51B60H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.60–1.00 .
D
H 61180 6118 H 0.15–0.21 0.40–0.80 0.035 0.040 0.15–0.35 . 0.40–0.80 .
E
H 61500 6150 H 0.47–0.54 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 .
C
H 81451 81B45 H 0.42–0.49 0.70–1.05 0.035 0.040 0.15–0.35 0.15–0.45 0.30–0.60 0.08–0.15
H 86170 8617 H 0.14–0.20 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
A304 − 20
TABLE 1 Continued
B
Chemical Composition, %
UNS Grade
A
Designation Designation
Carbon Manganese Phosphorus Sulfur Silicon Nickel Chromium Molybdenum
H 86200 8620 H 0.17–0.23 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86220 8622 H 0.19–0.25 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86250 8625 H 0.22–0.28 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86270 8627 H 0.24–0.30 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86300 8630 H 0.27–0.33 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
C
H 86301 86B30 H 0.27–0.33 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86370 8637 H 0.34–0.41 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86400 8640 H 0.37–0.44 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86420 8642 H 0.39–0.46 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86450 8645 H 0.42–0.49 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
C
H 86451 86B45 H 0.42–0.49 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86500 8650 H 0.47–0.54 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86550 8655 H 0.50–0.60 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86600 8660 H 0.55–0.65 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 87200 8720 H 0.17–0.23 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.20–0.30
H 87400 8740 H 0.37–0.44 0.70–1.05 0.15–0.35 0.35–0.75 0.35–0.65 0.20–0.30
H 88220 8822 H 0.19–0.25 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.30–0.40
H 92600 9260 H 0.55–0.65 0.65–1.10 0.035 0.040 1.70–2.20 . . .
H 93100 9310 H 0.07–0.13 0.40–0.70 0.035 0.040 0.15–0.35 2.95–3.55 1.00–1.45 0.08–0.15
C
H 94151 94B15 H 0.12–0.18 0.70–1.05 0.035 0.040 0.15–0.35 0.25–0.65 0.25–0.55 0.08–0.15
C
H 94171 94B17 H 0.14–0.20 0.70–1.05 0.035 0.040 0.15–0.35 0.25–0.65 0.25–0.55 0.08–0.15
C
H 94301 94B30 H 0.27–0.33 0.70–1.05 0.035 0.040 0.15–0.35 0.25–0.65 0.25–0.55 0.08–0.15
A
New designations established in accordance with Practice E527 and SAE J 1086, Recommended Practice for Numbering Metals and Alloys (UNS).
B
All values are maximums except where a range is provided.
C
These steels can be expected to have a 0.0005 % min boron content.
D
Vanadium content range is 0.10 to 0.15 %.
E
Minimum vanadium content is 0.15 %.
A
TABLE 2 Chemical Requirements of Carbon H-Steels
Chemical Composition, %
B
UNS Designation Grade Designation
Phosphorus, Sulfur,
Carbon Manganese Silicon
max max
H 10380 1038 H 0.34–0.43 0.50–1.00 0.040 0.050 0.15–0.35
H 10450 1045 H 0.42–0.51 0.50–1.00 0.040 0.050 0.15–0.35
H 15220 1522 H 0.17–0.25 1.00–1.50 0.040 0.050 0.15–0.35
H 15240 1524 H 0.18–0.26 1.25–1.75 0.040 0.050 0.15–0.35
H 15260 1526 H 0.21–0.30 1.00–1.50 0.040 0.050 0.15–0.35
H 15410 1541 H 0.35–0.45 1.25–1.75 0.040 0.050 0.15–0.35
C C
H 15211 15B21 H 0.17–0.24 0.70–1.20 0.040 0.050 0.15–0.35
C C
H 15351 15B35 H 0.31–0.39 0.70–1.20 0.040 0.050 0.15–0.35
C C
H 15371 15B37 H 0.30–0.39 1.00–1.50 0.040 0.050 0.15–0.35
C C
H 15411 15B41 H 0.35–0.45 1.25–1.75 0.040 0.050 0.15–0.35
C C
H 15481 15B48 H 0.43–0.53 1.00–1.50 0.040 0.050 0.15–0.35
C C
H 15621 15B62 H 0.54–0.67 1.00–1.50 0.040 0.050 0.40–0.60
A
Standard H Steels can be produced with a lead range of 0.15 to 0.35 %. Such steels are identified by inserting the letter “L” between the second and third numerals of
the grade designation, for example, 15L22 H. Lead is generally reported as a range of 0.15 to 0.35 %.
B
New designations established in accordance with Practice E527 and SAE J 1086, Recommended Practice for Numbering Metals and Alloys (UNS).
C
These steels can be expected to have 0.0005 % min boron content.
4.3 Band limits are shown graphically and as tabulations in 4.4 Two points from the tabulated values are commonly
Figs. 2-87, inclusive. For specifications purposes, the tabulated designated according to one of Methods A, B, C, D, or E,
values of Rockwell C hardness are used. Values below 20 which are defined in the following paragraphs. Those various
Rockwell C hardness (20 HRC) are not specified because such methods are illustrated graphically in Fig. 1.
values are below the normal range of the C scale. The graphs 4.4.1 Method A—The minimum and maximum hardness
are shown for convenience in estimating the hardness values valuesatanydesireddistance.ThismethodisillustratedinFig.
obtainable at various locations on the end quench test bar and 1 as points A-A and would be specified as 43 to 54 HRC at J3.
for various locations in oil or water quenched rounds. The Obviously the distance selected would be that distance on the
relationship between end-quench distance and bar diameter is end quench test bar that corresponds to the section used by the
approximate and should be used only as a guide. purchaser.
A304 − 20
Method Points on Example—End Quench
Charts Hardenability
A Minimum and maximum hardness values at a designated distance A-A HRC 43 to 54 at J3
B A hardness valu
...

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: A304 − 16 A304 − 20
Standard Specification for
Carbon and Alloy Steel Bars Subject to End-Quench
Hardenability Requirements
This standard is issued under the fixed designation A304; 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 hot-worked alloy, carbon, and carbon-boron steels in a variety of compositions and sizes, which
may attain specified depth of hardening in the end quench test. These steel compositions are identified by the suffix letter “H” added
to the conventional grade number.
1.2 This specification provides for analyses other than those listed under Tables 1 and 2. Special hardenability limits are also
permissible when approved by the purchaser and manufacturer.
1.3 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
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:
A29/A29M Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
A108 Specification for Steel Bar, Carbon and Alloy, Cold-Finished
A255 Test Methods for Determining Hardenability of Steel
E112 Test Methods for Determining Average Grain Size
E527 Practice for Numbering Metals and Alloys in the Unified Numbering System (UNS)
2.2 Society of Automotive Engineers (SAE) Standard:
J 1086 Numbering Metals and Alloys
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 hardenability—the relative ability of a steel to harden under heat treatment becomes apparent in the degree to which the
material hardens when quenched at different cooling rates. It is measured quantitatively, usually by noting the extent or depth of
hardening of a standard size and shape test specimen in a standardized quench. In the “end-quench” test the “depth of hardening”
is the distance along the specimen from the quenched end to a given hardness.
4. Ordering Information
4.1 Orders for material under this specification should include the following information, in proper sequence:
4.1.1 Quantity (weight),(weight);
4.1.2 Name of material (alloy, carbon, or carbon-boron steel),steel);
4.1.3 Cross-sectional shape,shape;
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.15
on Bars.
Current edition approved Dec. 1, 2016July 1, 2020. Published January 2017July 2020. Originally approved in 1947. Last previous edition approved in 20112016 as
A304 – 11.A304 – 16. DOI: 10.1520/A0304-16.10.1520/A0304-20.
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’ Document Summary page on the ASTM website.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.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
A304 − 20
A
TABLE 1 Chemical Requirements of Alloy H Steels
NOTE 1—Phosphorus and sulfur in electric-furnace steel (designated designated by the prefix letter “E”)“E” is 0.025 %, max.
NOTE 2—Small quantities of certain elements are present in alloy steels that are not specified or required. These elements are considered as incidental
and may be present to the following maximum amounts: copper, 0.35 %; nickel, 0.25 %; chromium, 0.20 %; molybdenum, 0.06 %.
NOTE 3—Chemical ranges and limits shown in this table are subject to the permissible variation for product analysis shown in Specification A29/A29M.
NOTE 4—Standard “H” Steels can be produced with a lead range of 0.15–0.35 %. 0.15 to 0.35 %. Such steels are identified by inserting the letter “L”
between the second and third numerals of the grade designation, for example, 41L40H. 41L40 H. Lead is generally reported as a range of
0.15–0.35 %.0.15 to 0.35 %.
B
Chemical Composition, %
UNS Grade
A
Designation Designation
Carbon Manganese Phosphorus Sulfur Silicon Nickel Chromium Molybdenum
H 13300 1330 H 0.27–0.33 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 13350 1335 H 0.32–0.38 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 13400 1340 H 0.37–0.44 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 13450 1345 H 0.42–0.49 1.45–2.05 0.035 0.040 0.15–0.35 . . .
H 40270 4027 H 0.24–0.30 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
B
H 40280 4028 H 0.24–0.30 0.60–1.00 0.15–0.35 . . 0.20–0.30
H 40280 4028 H 0.24–0.30 0.60–1.00 0.035 0.035–0.050 0.15–0.35 . . 0.20–0.30
H 40320 4032 H 0.29–0.35 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40370 4037 H 0.34–0.41 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40420 4042 H 0.39–0.46 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 40470 4047 H 0.44–0.51 0.60–1.00 0.035 0.040 0.15–0.35 . . 0.20–0.30
H 41180 4118 H 0.17–0.23 0.60–1.00 0.035 0.040 0.15–0.35 . 0.30–0.70 0.08–0.15
H 41300 4130 H 0.27–0.33 0.30–0.70 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41350 4135 H 0.32–0.38 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41370 4137 H 0.34–0.41 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41400 4140 H 0.37–0.44 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41420 4142 H 0.39–0.46 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41450 4145 H 0.42–0.49 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41470 4147 H 0.44–0.51 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41500 4150 H 0.47–0.54 0.65–1.10 0.035 0.040 0.15–0.35 . 0.75–1.20 0.15–0.25
H 41610 4161 H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.65–0.95 0.25–0.35
H 43200 4320 H 0.17–0.23 0.40–0.70 0.035 0.040 0.15–0.35 1.55–2.00 0.35–0.65 0.20–0.30
H 43400 4340 H 0.37–0.44 0.55–0.90 0.035 0.040 0.15–0.35 1.55–2.00 0.65–0.95 0.20–0.30
H 43406 E4340 H 0.37–0.44 0.60–0.95 0.035 0.040 0.15–0.35 1.55–2.00 0.65–0.95 0.20–0.30
H 44190 4419 H 0.17–0.23 0.35–0.75 0.035 0.040 0.15–0.35 . . 0.45–0.60
H 46200 4620 H 0.17–0.23 0.35–0.75 0.035 0.040 0.15–0.35 1.55–2.00 . 0.20–0.30
H 46210 4621 H 0.17–0.23 0.60–1.00 0.035 0.040 0.15–0.35 1.55–2.00 . 0.20–0.30
H 46260 4626 H 0.23–0.29 0.40–0.70 0.035 0.040 0.15–0.35 0.65–1.05 . 0.15–0.25
H 47180 4718 H 0.15–0.21 0.60–0.95 0.035 0.040 0.15–0.35 0.85–1.25 0.30–0.60 0.30–0.40
H 47200 4720 H 0.17–0.23 0.45–0.75 0.035 0.040 0.15–0.35 0.85–1.25 0.30–0.60 0.15–0.25
H 48150 4815 H 0.12–0.18 0.30–0.70 0.035 0.040 0.15–0.35 3.20–3.80 . 0.20–0.30
H 48170 4817 H 0.14–0.20 0.30–0.70 0.035 0.040 0.15–0.35 3.20–3.80 . 0.20–0.30
H 48200 4820 H 0.17–0.23 0.40–0.80 0.035 0.040 0.15–0.35 3.20–3.80 . 0.20–0.30
C
H 50401 50B40 H 0.37–0.44 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
C
H 50441 50B44 H 0.42–0.49 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
H 50460 5046 H 0.43–0.50 0.65–1.10 0.035 0.040 0.15–0.35 . 0.13–0.43 .
C
H 50461 50B46 H 0.43–0.50 0.65–1.10 0.035 0.040 0.15–0.35 . 0.13–0.43 .
C
H 50501 50B50 H 0.47–0.54 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
C
H 50601 50B60 H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.30–0.70 .
H 51200 5120 H 0.17–0.23 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51300 5130 H 0.27–0.33 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 .
H 51320 5132 H 0.29–0.35 0.50–0.90 0.035 0.040 0.15–0.35 . 0.65–1.10 .
H 51350 5135 H 0.32–0.38 0.50–0.90 0.035 0.040 0.15–0.35 . 0.70–1.15 .
H 51400 5140 H 0.37–0.44 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51450 5145 H 0.42–0.49 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51470 5147 H 0.45–0.52 0.60–1.05 0.035 0.040 0.15–0.35 . 0.80–1.25 .
H 51500 5150 H 0.47–0.54 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51550 5155 H 0.50–0.60 0.60–1.00 0.035 0.040 0.15–0.35 . 0.60–1.00 .
H 51600 5160 H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.60–1.00 .
C
H 51601 51B60H 0.55–0.65 0.65–1.10 0.035 0.040 0.15–0.35 . 0.60–1.00 .
D
H 61180 6118 H 0.15–0.21 0.40–0.80 0.035 0.040 0.15–0.35 . 0.40–0.80 .
E
H 61500 6150 H 0.47–0.54 0.60–1.00 0.035 0.040 0.15–0.35 . 0.75–1.20 .
C
H 81451 81B45 H 0.42–0.49 0.70–1.05 0.035 0.040 0.15–0.35 0.15–0.45 0.30–0.60 0.08–0.15
A304 − 20
TABLE 1 Continued
B
Chemical Composition, %
UNS Grade
A
Designation Designation
Carbon Manganese Phosphorus Sulfur Silicon Nickel Chromium Molybdenum
H 86170 8617 H 0.14–0.20 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86200 8620 H 0.17–0.23 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86220 8622 H 0.19–0.25 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86250 8625 H 0.22–0.28 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86270 8627 H 0.24–0.30 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86300 8630 H 0.27–0.33 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
C
H 86301 86B30 H 0.27–0.33 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86370 8637 H 0.34–0.41 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86400 8640 H 0.37–0.44 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86420 8642 H 0.39–0.46 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86450 8645 H 0.42–0.49 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
C
H 86451 86B45 H 0.42–0.49 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86500 8650 H 0.47–0.54 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86550 8655 H 0.50–0.60 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 86600 8660 H 0.55–0.65 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.15–0.25
H 87200 8720 H 0.17–0.23 0.60–0.95 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.20–0.30
H 87400 8740 H 0.37–0.44 0.70–1.05 0.15–0.35 0.35–0.75 0.35–0.65 0.20–0.30
H 88220 8822 H 0.19–0.25 0.70–1.05 0.035 0.040 0.15–0.35 0.35–0.75 0.35–0.65 0.30–0.40
H 92600 9260 H 0.55–0.65 0.65–1.10 0.035 0.040 1.70–2.20 . . .
H 93100 9310 H 0.07–0.13 0.40–0.70 0.035 0.040 0.15–0.35 2.95–3.55 1.00–1.45 0.08–0.15
C
H 94151 94B15 H 0.12–0.18 0.70–1.05 0.035 0.040 0.15–0.35 0.25–0.65 0.25–0.55 0.08–0.15
C
H 94171 94B17 H 0.14–0.20 0.70–1.05 0.035 0.040 0.15–0.35 0.25–0.65 0.25–0.55 0.08–0.15
C
H 94301 94B30 H 0.27–0.33 0.70–1.05 0.035 0.040 0.15–0.35 0.25–0.65 0.25–0.55 0.08–0.15
A
New designations established in accordance with Practice E527 and SAE J 1086, Recommended Practice for Numbering Metals and Alloys (UNS).
B
Sulfur content range is 0.035 to 0.050 %. All values are maximums except where a range is provided.
C
These steels can be expected to have a 0.0005 % min boron content.
D
Vanadium content range is 0.10 to 0.15 %.
E
Minimum vanadium content is 0.15 %.
A
TABLE 2 Chemical Requirements of Carbon H-Steels
Chemical Composition, %
B
UNS Designation Grade Designation
Phosphorus, Sulfur,
Carbon Manganese Silicon
max max
H 10380 1038 H 0.34–0.43 0.50–1.00 0.040 0.050 0.15–0.35
H 10450 1045 H 0.42–0.51 0.50–1.00 0.040 0.050 0.15–0.35
H 15220 1522 H 0.17–0.25 1.00–1.50 0.040 0.050 0.15–0.35
H 15240 1524 H 0.18–0.26 1.25–1.75 0.040 0.050 0.15–0.35
H 15260 1526 H 0.21–0.30 1.00–1.50 0.040 0.050 0.15–0.35
H 15410 1541 H 0.35–0.45 1.25–1.75 0.040 0.050 0.15–0.35
C C
H 15211 15B21 H 0.17–0.24 0.70–1.20 0.040 0.050 0.15–0.35
C C
H 15351 15B35 H 0.31–0.39 0.70–1.20 0.040 0.050 0.15–0.35
C C
H 15371 15B37 H 0.30–0.39 1.00–1.50 0.040 0.050 0.15–0.35
C C
H 15411 15B41 H 0.35–0.45 1.25–1.75 0.040 0.050 0.15–0.35
C C
H 15481 15B48 H 0.43–0.53 1.00–1.50 0.040 0.050 0.15–0.35
C C
H 15621 15B62 H 0.54–0.67 1.00–1.50 0.040 0.050 0.40–0.60
A
Standard H Steels can be produced with a lead range of 0.15–0.35 %. 0.15 to 0.35 %. Such steels are identified by inserting the letter “L” between the second and third
numerals of the grade designation, for example, 15L22 H. Lead is generally reported as a range of 0.15–0.35 %.0.15 to 0.35 %.
B
New designations established in accordance with Practice E527 and SAE J 1086, Recommended Practice for Numbering Metals and Alloys (UNS).
C
These steels can be expected to have 0.0005 % min boron content.
4.1.4 Size,Size;
4.1.5 Length,Length;
4.1.6 Grade,Grade;
4.1.7 End-quenched hardenability (see Section 9),);
4.1.8 Report of heat analysis, if desired (see Section 7),);
4.1.9 Special straightness, if required,required;
4.1.10 ASTM designation and date of issue,issue;
4.1.11 End use or special requirements,requirements; and
A304 − 20
4.1.12 Leaded steel, when required.
NOTE 1—A typical ordering description is as follows: 10 000 lb, alloy bars, round, 4.0 in. dia by 10 ft, Grade 1340H, J 40 ⁄56 = ⁄16 in., heat analysis
required, ASTM A304, dated ________, worm gear.
4.2 The purchaser shall specify the desired grade, including the suffix letter “H,” in accordance with Table 1 or Table 2.
Method Points on Example—End Quench
Charts Hardenability
A Minimum and maximum hardness values at a designated distance A-A HRC 43 to 54 at J3
B A hardness value at minimum and maximum distances B-B HRC 39 at J4 minimum and J9 maximum
C The maximum hardness values at two designated distances C-C HRC50 at J5 maximum
HRC 34 at J12 maximum
C The maximum hardness values at two designated distances C-C HRC 50 at J5 maximum
HRC 34 at J12 maximum
D Two minimum hardness values at two distances D-D HRC 35 at J5 minimum
HRC 21 at J16 minimum
E Any minimum hardness plus any maximum hardness E-E HRC 32 at J6 minimum
HRC 37 at J10 maximum
FIG. 1 Examples Illustrating Alternative Method of Specifying Hardenability Requirements
(tabulated hardness values are used in ordering)
A304 − 20
4.3 Band limits are shown graphically and as tabulations in Figs. 2-87, inclusive. For specifications purposes, the tabulated
values of Rockwell C hardness are used. Values below 20 Rockwell C hardness (20 HRC) are not specified because such values
are below the normal range of the C scale. The graphs are shown for convenience in estimating the hardness values obtainable at
various locations on the end quench test
...