ASTM A914/A914M-92(2005)
(Specification)Standard Specification for Steel Bars Subject to Restricted End-Quench Hardenability Requirements
Standard Specification for Steel Bars Subject to Restricted End-Quench Hardenability Requirements
ABSTRACT
This specification covers hot-worked alloy and carbon-boron steels designed to attain restricted depth of hardening in the end-quench test. These steel compositions are identified by the suffix letter RH added to the conventional grade number. The steel shall be made by one or more of the following primary processes: open-hearth, basic-oxygen, or electric furnace. The primary melting may incorporate separate degassing or ladle refining and may be followed by secondary melting using electroslag remelting or vacuum arc remelting. Where secondary melting is employed, the heat shall be defined as all the ingots remelted from a single primary heat. Immediately after hot working, the bars shall be allowed to cool when necessary to a temperature below the critical range under suitable conditions, to prevent injury by too rapid cooling. The steel shall have an austenitic grain size of five to eight. The grain structure shall be considered satisfactory when a minimum of 70% of the rated grains are within the specified size limits. Hardenability values specified are based on fine-grain steels and are not applicable to coarse-grain steel. All forged and rolled hardenability test specimens must be normalized prior to testing. Cast specimens need not be normalized.
SCOPE
1.1 This specification covers hot-worked alloy and carbon-boron steels designed to attain restricted depth of hardening in the end-quench test. These steel compositions are identified by the suffix letter "RH" added to the conventional grade number.
1.2 In general, steels with restricted hardenability (RH steels) will exhibit a hardness range not greater than 5 HRC at the initial position on the end-quench hardenability bar and not greater than 65 % of the hardness range for standard H-band steels (Specification A 304) in the inflection region. Generally the restricted hardenability band follows the middle of the corresponding standard H-band. An example of the RH band compared with the H band is given for Grade 4140 in .
1.3 This specification is expressed in both inch-pound units and SI units. However, the material will be supplied to inch-pound units unless the purchase order specifies the "M" specification designation.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: A914/A914M – 92 (Reapproved 2005)
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 J 1868 Restricted Hardenability Bands for Selected Alloy
Steels
1.1 This specification covers hot-worked alloy and carbon-
boron steels designed to attain restricted depth of hardening in
3. Terminology
the end-quench test. These steel compositions are identified by
3.1 Definitions of Terms Specific to This Standard:
the suffix letter “RH” added to the conventional grade number.
3.1.1 hardenability—the relative ability of a steel to harden
1.2 In general, steels with restricted hardenability (RH
under heat treatment becomes apparent in the degree to which
steels) will exhibit a hardness range not greater than 5 HRC at
the material hardens when quenched at different cooling rates.
the initial position on the end-quench hardenability bar and not
3.1.1.1 Discussion—Hardenability is measured quantita-
greater than 65 % of the hardness range for standard H-band
tively, usually by noting the extent or depth of hardening of a
steels (Specification A304) in the inflection region. Generally
standard size and shape test specimen in a standardized
the restricted hardenability band follows the middle of the
quench. In the end-quench test the depth of hardening is the
corresponding standard H-band. An example of the RH band
distance along the specimen from the quenched end to a given
compared with the H band is given for Grade 4140 in Fig. 1.
hardness.
1.3 This specification is expressed in both inch-pound units
and SI units. However, the material will be supplied to
4. Ordering Information
inch-pound units unless the purchase order specifies the “M”
4.1 Orders for material under this specification should
specification designation.
include the following information, in proper sequence:
2. Referenced Documents 4.1.1 Quantity (weight),
2 4.1.2 Name of material (alloy or carbon-boron steel),
2.1 ASTM Standards:
4.1.3 Cross-sectional shape,
A29/A29M Specification for Steel Bars, Carbon and Alloy,
4.1.4 Size,
Hot-Wrought, General Requirements for
4.1.5 Length,
A255 Test Methods for Determining Hardenability of Steel
4.1.6 Grade,
A304 Specification for Carbon andAlloy Steel Bars Subject
4.1.7 End-quenched hardenability (see Section 9),
to End-Quench Hardenability Requirements
4.1.8 Report of heat analysis, if desired (see Section 7),
E112 Test Methods for Determining Average Grain Size
3 4.1.9 Special straightness, if required,
2.2 SAE Standards:
4.1.10 ASTM designation and date of issue, and
J 406 Methods of Determining Hardenability of Steels
4.1.11 End use or special requirements.
J 1268 Hardenability Bands for Carbon and Alloy H Steels
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
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
required,completehardenabilitydatarequired,ASTMAXXX,[AXXXM]
Stainless Steel, and RelatedAlloys and is the direct responsibility of Subcommittee
dated _____ worm gear.
A01.15 on Bars.
Current edition approved March 1, 2005. Published March 2005. Originally
4.2 The purchaser shall specify the desired grade, including
approved in 1992. Last previous edition approved in 1999 as A914/
the suffix letters “RH”, in accordance with Table 1.
´1
A914M - 92(1999) . DOI: 10.1520/A0914_A0914M-92R05.
4.3 Band limits are shown graphically and as tabulations in
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 Figs. 2-23, inclusive. For specification purposes, one must use
Standards volume information, refer to the standard’s Document Summary page on
tabulated values of Rockwell hardness (HRC) as a function of
the ASTM website.
distance from the quenched end of the hardenability bar, either
Available from Society of Automotive Engineers (SAE), 400 Commonwealth
in inch-pound units (sixteenths of an inch) or in SI units
Dr., Warrendale, PA 15096-0001.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
A914/A914M – 92 (2005)
(millimetres). Values below 20 HRC are not specified because 5.2 Slow Cooling—Immediately after hot working, the bars
such values are not accurate. shallbeallowedtocoolwhennecessarytoatemperaturebelow
thecriticalrangeundersuitableconditions,topreventinjuryby
4.3.1 Band limits shown graphically are so depicted for
too rapid cooling.
convenience in estimating the hardness values at various
intermediate locations on the end quench test bar for quick
6. General Requirements
comparisons of the various RH grades. The values of “Ap-
proximate Diameter of Rounds with SameAs-Quenched Hard- 6.1 Material furnished under this specification shall con-
form to the applicable requirements of the current edition of
ness” shown above each RH-band, were selected from ranges
SpecificationA29/A29M, unless otherwise provided for in this
appearing in Fig. 7 of SAE J 406. The RH-bands are presented
specification.
graphically, with distances from the quenched end in both
inch-pound units and also SI units.
7. Chemical Requirements
4.4 For specification purposes, RH-band steels shall exhibit
hardness within the minimum and maximum HRC range 7.1 The heat analysis shall conform to the requirements as
to chemical composition prescribed in Table 1 for the grade
specified at the J1 (J1.5-mm) position and shall meet one
specified by the purchaser.
additional minimum and one additional maximum value. In
this specification, the two additional hardness values shall
8. Grain Size Requirements
represent the approximate hardness for 50 % martensite for the
minimum and maximum specified carbon content, respectively
8.1 The steel shall have an austenitic grain size of five to
(exceptwherehardenabilityistoohigh;thenthetwoadditional
eight.The grain structure shall be considered satisfactory when
hardness control values shall be five HRC points below the
a minimum of 70 % of the rated grains are within the specified
maximum hardness value specified at the J1 (J1.5-mm) posi- size limits.
tion). 8.2 Hardenability values specified are based on fine-grain
steels and are not applicable to coarse-grain steel.
4.4.1 In general, these points define the critical locations of
the Jominy hardenability band for purposes of characterizing
9. End-Quench Hardenability Requirements
heat treatment response. The four specification points are
circled in the tables of hardness versus Jominy distance and on
9.1 The end-quench hardenability shall conform to the
the RH-bands. For all other Jominy positions, a tolerance of requirements specified on the purchase order.
two points HRC is permitted for a maximum consecutive
9.2 Hardenability values shall be specified in accordance
⁄16-in. or 5-mm Jominy distance on the restricted hardenability withtheapplicablevaluesinFigs.2-23,inclusive,forthegrade
band. specified.
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
exhibit a hardness at J1 not less than 54 HRC, nor more than
10.1 Number and Location—The number and location of
59HRC.AtJ12,thetestbarmustexhibithardnessnotlessthan test specimens shall be in accordance with the manufacturer’s
43 HRC, but the maximum hardness can be as high as 52 HRC standard practice and shall adequately represent the harden-
(or even 54 HRC if the region of the test bar is chosen as the ability of each heat.
exception). At J20, the bar must exhibit hardness not greater 10.2 Thermal Treatme
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