ASTM A914/A914M-92(2011)

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Designation:A914/A914M −92 (Reapproved 2011)
Standard Specification for
Steel Bars Subject to Restricted End-Quench Hardenability
Requirements
This standard is issued under the fixed designationA914/A914M; 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 2.2 SAE Standards:
J 406 Methods of Determining Hardenability of Steels
1.1 This specification covers hot-worked alloy and carbon-
J 1268 Hardenability Bands for Carbon and Alloy H Steels
boron steels designed to attain restricted depth of hardening in
J 1868 Restricted Hardenability Bands for Selected Alloy
the end-quench test. These steel compositions are identified by
Steels
the suffix letter “RH” added to the conventional grade number.
1.2 In general, steels with restricted hardenability (RH
3. Terminology
steels) will exhibit a hardness range not greater than 5 HRC at
3.1 Definitions of Terms Specific to This Standard:
the initial position on the end-quench hardenability bar and not
3.1.1 hardenability—the relative ability of a steel to harden
greater than 65 % of the hardness range for standard H-band
under heat treatment becomes apparent in the degree to which
steels (Specification A304) in the inflection region. Generally
the material hardens when quenched at different cooling rates.
the restricted hardenability band follows the middle of the
3.1.1.1 Discussion—Hardenability is measured
corresponding standard H-band. An example of the RH band
quantitatively, usually by noting the extent or depth of hard-
compared with the H band is given for Grade 4140 in Fig. 1.
ening of a standard size and shape test specimen in a
1.2.1 ThevaluesstatedineitherSIunitsorinch-poundunits
standardized quench. In the end-quench test the depth of
are to be regarded separately as standard. The values stated in
hardening is the distance along the specimen from the
each system may not be exact equivalents; therefore, each
quenched end to a given hardness.
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance
4. Ordering Information
with the standard.
4.1 Orders for material under this specification should
1.3 This specification is expressed in both inch-pound units
include the following information, in proper sequence:
and SI units. However, the material will be supplied to
4.1.1 Quantity (weight),
inch-pound units unless the purchase order specifies the “M”
4.1.2 Name of material (alloy or carbon-boron steel),
specification designation.
4.1.3 Cross-sectional shape,
4.1.4 Size,
2. Referenced Documents
4.1.5 Length,
2.1 ASTM Standards:
4.1.6 Grade,
A29/A29M SpecificationforGeneralRequirementsforSteel
4.1.7 End-quenched hardenability (see Section 9),
Bars, Carbon and Alloy, Hot-Wrought
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,
A304 Specification for Carbon andAlloy Steel Bars Subject
4.1.10 ASTM designation and date of issue, and
to End-Quench Hardenability Requirements
4.1.11 End use or special requirements.
E112 Test Methods for Determining Average Grain Size
NOTE 1—A typical ordering description is as follows: 10 000 lb, alloy
bars, round, 4.0-in. diameter by 10 ft, Grade 4140RH, heat analysis
required,completehardenabilitydatarequired,ASTMAXXX,[AXXXM]
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee dated _____ worm gear.
A01.15 on Bars.
4.2 The purchaser shall specify the desired grade, including
Current edition approved April 1, 2011. Published June 2011. Originally
the suffix letters “RH”, in accordance with Table 1.
approved in 1992. Last previous edition approved in 2005 as A914/
A914M - 92(2005). DOI: 10.1520/A0914_A0914M-92R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
the ASTM website. PA 15096-0001, http://www.sae.org.
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A914/A914M−92 (2011)
4.3 Band limits are shown graphically and as tabulations in vacuum arc remelting. Where secondary melting is employed,
Figs. 2-23, inclusive. For specification purposes, one must use theheatshallbedefinedasalltheingotsremeltedfromasingle
tabulated values of Rockwell hardness (HRC) as a function of primary heat.
distance from the quenched end of the hardenability bar, either
5.2 Slow Cooling—Immediately after hot working, the bars
in inch-pound units (sixteenths of an inch) or in SI units
shallbeallowedtocoolwhennecessarytoatemperaturebelow
(millimetres). Values below 20 HRC are not specified because
thecriticalrangeundersuitableconditions,topreventinjuryby
such values are not accurate.
too rapid cooling.
4.3.1 Band limits shown graphically are so depicted for
convenience in estimating the hardness values at various
6. General Requirements
intermediate locations on the end quench test bar for quick
6.1 Material furnished under this specification shall con-
comparisons of the various RH grades. The values of “Ap-
form to the applicable requirements of the current edition of
proximate Diameter of Rounds with SameAs-Quenched Hard-
Specification A29/A29M, unless otherwise provided for in this
ness” shown above each RH-band, were selected from ranges
specification.
appearing in Fig. 7 of SAE J 406. The RH-bands are presented
graphically, with distances from the quenched end in both
7. Chemical Requirements
inch-pound units and also SI units.
7.1 The heat analysis shall conform to the requirements as
4.4 For specification purposes, RH-band steels shall exhibit
to chemical composition prescribed in Table 1 for the grade
hardness within the minimum and maximum HRC range
specified by the purchaser.
specified at the J1 (J1.5-mm) position and shall meet one
additional minimum and one additional maximum value. In
8. Grain Size Requirements
this specification, the two additional hardness values shall
8.1 The steel shall have an austenitic grain size of five to
represent the approximate hardness for 50 % martensite for the
eight.The grain structure shall be considered satisfactory when
minimum and maximum specified carbon content, respectively
a minimum of 70 % of the rated grains are within the specified
(exceptwherehardenabilityistoohigh;thenthetwoadditional
size limits.
hardness control values shall be five HRC points below the
8.2 Hardenability values specified are based on fine-grain
maximum hardness value specified at the J1 (J1.5-mm) posi-
steels and are not applicable to coarse-grain steel.
tion).
4.4.1 In general, these points define the critical locations of
9. End-Quench Hardenability Requirements
the Jominy hardenability band for purposes of characterizing
9.1 The end-quench hardenability shall conform to the
heat treatment response. The four specification points are
requirements specified on the purchase order.
circled in the tables of hardness versus Jominy distance and on
the RH-bands. For all other Jominy positions, a tolerance of
9.2 Hardenability values shall be specified in accordance
two points HRC is permitted for a maximum consecutive
withtheapplicablevaluesinFigs.2-23,inclusive,forthegrade
⁄16-in. or 5-mm Jominy distance on the restricted hardenability
specified.
band.
4.4.2 For example, referring to Fig. 9, a hardenability test 10. Test Specimens
bar of a steel meeting the requirements for 4140RH must
10.1 Number and Location—The number and location of
exhibit a hardness at J1 not less than 54 HRC, nor more than
test specimens shall be in accordance with the manufacturer’s
59HRC.AtJ12,thetestbarmustexhibithardnessnotlessthan
standard practice and shall adequately represent the harden-
43 H
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