ASTM A729-93(1999)
(Specification)Standard Specification for Alloy Steel Axles, Heat-Treated, for Mass Transit and Electric Railway Service
Standard Specification for Alloy Steel Axles, Heat-Treated, for Mass Transit and Electric Railway Service
SCOPE
1.1 This specification covers quenched and tempered alloy steel axles for mass transit and commuter cars in electric railway service.
1.2 This specification is for solid design roller bearing axles with machined bodies.
1.3 Various axle designs are used for this service including motor and nonmotor with either inboard or outboard journals.
1.4 Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the order.
1.5 The values stated in inch-pound units are to be regarded as the standard.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: A 729 – 93 (Reapproved 1999)
Standard Specification for
Alloy Steel Axles, Heat-Treated, for Mass Transit and
Electric Railway Service
This standard is issued under the fixed designation A 729; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 Quantity.
3.1.2 Purchaser’s drawing showing complete details per-
1.1 This specification covers quenched and tempered alloy
taining to dimensions, tolerances if more restrictive than those
steel axles for mass transit and commuter cars in electric
contained in this specification, degree of finish and location of
railway service.
stamping and any other information that will aid the manufac-
1.2 This specification is for solid design roller bearing axles
turer to furnish a satisfactory product.
with machined bodies.
3.1.3 Supplementary requirements, if any.
1.3 Various axle designs are used for this service including
motor and nonmotor with either inboard or outboard journals.
4. Manufacture
1.4 Supplementary requirements are provided for use when
4.1 Process—The steel shall be made by any of the follow-
additional testing or inspection is desired. These shall apply
ing processes: open-hearth, electric-furnace, or basic-oxygen.
only when specified individually by the purchaser in the order.
4.2 Discard—A sufficient discard shall be made to assure
1.5 The values stated in inch-pound units are to be regarded
freedom from piping and undue segregation.
as the standard.
4.3 Forging Practice—The axle may be made direct from
2. Referenced Documents the ingot or from blooms, the total reduction from ingot or
strand cast blooms to forging being not less than 3 to 1, unless
2.1 ASTM Standards:
otherwise specified.
A 370 Test Methods and Definitions for MechanicalTesting
4.4 Cooling and Heating:
of Steel Products
4.4.1 After axle blooms are produced they shall be slow
E112 Test Methods for Determining the Average Grain
cooled in closed containers, hoods, or furnaces.
Size
4.4.2 Blooms shall be reheated for forging in a manner that
E 127 Practice for Fabricating and Checking Aluminum
4 will prevent internal bursts and overheating.
Alloy Ultrasonic Standard Reference Blocks
4.4.3 After forging, axles shall be slow cooled in closed
E 381 Method of Macroetch Testing Steel Bars, Billets,
3 containers, covered conveyors, or hoods. If axles are heat-
Blooms, and Forgings
treated directly from the forging, they shall be slow cooled
NOTE 1—References to analysis standards are for guidance only; other
following the final heat treatment.
methods of equivalent accuracy may be used.
4.4.4 Axles that are heat-treated directly from forging (1)
shall be cooled below the transformation temperature or to
3. Ordering Information
approximately 1000°F (538°C) before any reheating operation,
3.1 Orders for material under this specification shall include
and (2) must not be permitted to cool below 500°F (260°C)
the following information:
without slow cooling as defined in 4.4.3.
NOTE 2—As the temperature of the axles approaches the minimum of
This specification is under the jurisdiction of ASTM Committee A-1 on Steel,
500°F (260°C) a supplemental heat source may be necessary to assure an
Stainless Steel, and RelatedAlloys and is the direct responsibility of Subcommittee
effective slow cooling cycle.
A01.06 on Steel Forgings and Billets.
4.4.5 When properly vacuum-degassed steel is used, the
Current edition approved Dec. 15, 1993. Published February 1994. Originally
published as A 729–76. Last previous edition A 729–81(1988).
slow cooling requirements of 4.4.1, 4.4.3, and 4.4.4 may be
Annual Book of ASTM Standards, Vol 01.03.
omitted but axle blooms must then be pile cooled.
Annual Book of ASTM Standards, Vol 03.01.
4.5 Heat Treatment:
Annual Book of ASTM Standards, Vol 03.03.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
A 729 – 93 (1999)
TABLE 2 Permissible Variations for Product Analysis (for Cross
4.5.1 Quenching—After heating to a suitable temperature
2 2
Section 100 in. (645 cm ) and Under)
the axles shall be quenched in a suitable medium under
reasonably uniform conditions.Afurnace charge thus treated is
NOTE—Product cross-sectional area is defined as either:
(a) maximum cross-sectional area of rough machined forging (excluding
termed a quenching charge.
boring),
4.5.2 Tempering—Axles shall be reheated gradually to, and
(b) maximum cross-sectional area of the unmachined forging, or
held at, a suitable temperature below the critical range and
(c) maximum cross-sectional area of the billet, bloom, or slab.
shall then be allowed to cool under suitable conditions. A
Area taken at right angles to the axis of the original ingot or billet.
furnace charge thus treated is termed a tempering charge.
Permissible Variations, Over the
4.5.3 Heat treatment may be performed in either batch-type
Element Maximum Limit or Under the
furnaces or continuous furnaces. Minimum Limit, %
4.6 Straightening—Straightening shall be done before ma-
Manganese 0.06
Phosphorus 0.008
chining and preferably at a temperature not lower than 950°F
Sulfur 0.008
(510°C). Straightening performed at temperatures lower than
Silicon 0.02
950°F shall be followed by stress relieving or applicable heat
treatment.
5. Chemical Requirements
7. Tension Test Requirements
5.1 Chemical Composition—The steel shall conform to the
7.1 Tension tests shall be made in accordance with Test
chemical requirements specified in Table 1 or to the composi-
Methods A 370.
tion agreed upon by the manufacturer and the purchaser.
7.1.1 Axles shall conform to the requirements in Table 3.
5.2 Heat Analysis—An analysis of each heat of steel shall
7.1.2 The diameter of the test prolongation of axle forgings
be made by the manufacturer to determine the percentage of
shall be determined by the forged diameter of the journal.
carbon, manganese, phosphorus, sulfur, and silicon. The
7.1.3 The yield strength prescribed in Table 3 shall be
chemical composition thus determined shall be reported to the
determined by a strain gage or extensometer reading to 0.0002
purchaser or his representative and shall conform to the
in. (0.005 mm). Yield strength may be defined as the stress at
requirements of 5.1.
0.6 %totalstrainunderloadorasthestressat0.2 %offset.The
5.3 Product Analysis—An analysis may be made by the
method described in Test Methods A 370 shall be followed.
purchaser from one axle representing each heat. The chemical
After the yield point has been passed the extensometer may
compositionthusdeterminedshallconformtotherequirements
then be removed and the test continued to determine the tensile
of 5.1 subject to tolerances included inTable 2.The sample for
strength.
these analyses shall be taken from one end of the test axle or
7.1.4 Tests shall be made only after final heat treatment.
full-sized prolongation at a point midway between the center
7.1.5 Tension Test Specimens:
and surface. If drillings are taken, they shall be obtained using
7.1.5.1 Tension test specimens shall be taken from the test
a ⁄8-in. (16-mm) diameter drill or turnings may be taken from
prolongationoranaxleinaccordancewiththeprovisionin7.2.
a tension test specimen.
7.1.5.2 Unless otherwise specified, the axis of the specimen
shall be located at any point midway between the center and
6. Metallurgical Requirements
surface of the axle or full-sized prolongation and shall be
6.1 A specimen, representing each heat in each heat- parallel to the axis of the axle.
treatment lot, shall be taken for microscopical test from the 7.1.5.3 The tension test specimen shall be machined to the
tension test specimen. This section for microscopical test shall form and dimensions shown in Fig. 6 of Test Methods A 370
be cut from the large undistorted portion of the tension test covering the standard round tension test specimen with a 2-in.
specimen in such a way as will give a face transverse to the (50-mm) gage length.
axis of the axle. 7.2 Prolongation for Test:
6.2 The face shall be polished practically free of scratches 7.2.1 For test purposes, prolongations shall be attached to at
and shall be etched to define the microstructure. The specimen least 5 % of the axles in each heat in each heat-treating lot.
shall be examined under a magnification of 100 diameters.
7.2.2 If axles with prolongations have been expended then
6.3 The entire specimen shall show a uniform, fine-grained axles may be used for test procurement.
structure of no. 5 or finer as measured in accordance with Test
7.3 Number of Tests:
MethodsE112. 7.3.1 Unless otherwise specified by the purchaser, mechani-
cal tests shall be made as covered in 7.3.2 and 7.3.3.
7.3.2 Where batch-type furnaces are used, one test per heat
TABLE 1 Chemical Requirements per size classification is required, but each test shall represent
no more than 70 axles. The axles represented by this test shall
Element Composition, %
be called a heat-treatment lot.
Carbon, max 0.60
Manganese 1.30–1.70 7.3.3 Where continuous heat-treating furnaces are used, one
Phosphorus, max 0.045
test per heat per size classification is required, but each test
Sulfur, max 0.050
shallrepresentnomorethan70axles.Theaxlesrepresentedby
Silicon, min 0.15
this test shall be called a heat-treatment lot.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
A 729 – 93 (1999)
TABLE 3 Tensile Requirements
Test Prolongation Diameter
Elongation in 2 in Reduction of Area,
Over Not Over Tensile Strength, min Yield Strength, min
or 50 mm, min, % min, %
in. mm in. mm ksi MPa ksi MPa
4 102 7 178 100 690 65 450 20 45
7.3.4 If any test specimen fails because of a mechanical 8.4.2 Scanning:
condition of the testing apparatus it may be discarded and 8.4.2.1 Scanning shall be performed from both end faces,
another specimen taken.
which shall have a surface finish of 125 µin. (3.18 µm)
7.4 Retest: maximum. The scanning shall include the maximum end face
7.4.1 If the results of the mechanical tests of any lot do not
area obtainable by manual or automated inspection techniques.
conform to the requirements specified because a flaw devel-
8.4.2.2 During scanning the amplitude of the indication
oped in the test specimen during testing, a retest shall be
from the end face opposite the search unit shall be monitored
allowedifthedefectisnotcausedbyruptures,cracks,orflakes
and the amplitudes of all discontinuity indications shall be
in the steel.
evaluated with respect to the distance from the test surface (see
7.4.2 If the results of the mechanical tests of any lot do not
8.4.3 and 8.7.2).
conform to the requirements specified, the axles may be
8.4.3 Distance-Amplitude Correction— The amplitude of
retreated, but not more than three additional times, and retests
an ultrasonic indication must be considered in relation to its
shall be made in accordance with Section 7.
distance from the testing surface to evaluate its significance.
This can be accomplished by an electronic device or by
8. Nondestructive Testing Requirements
distance-amplitude curves (DAC), which are described in
8.1 Ultrasonic Inspection—The purpose of this inspection
8.7.2.
is to evaluate the quality of new axles ( 1) by determining end
8.5 Rejection:
face to end face penetrability, and ( 2) by detecting disconti-
8.5.1 Longitudinal Penetration—Axles that do not produce
nuities that may be harmful to axle service.
a 40 % FSH back reflection from the end of face opposite the
8.2 Equipment—Equipment requirements are as follows:
search unit shall be rejected or made acceptable by heat
8.2.1 The instrument used must be a pulse echo type.
treatment.
8.2.2 The instrument shall be operated at a 2 ⁄4-MHz fre-
8.5.2 Discontinuity Test—The axle shall be rejected if the
quency for both penetrability and discontinuity detection.
amplitude of any discontinuity indication exceeds the indica-
8.2.3 The instrument may use various transducers, namely,
tion levels obtained from the flat-bottom holes listed in the
quartz 1 in. (25.4 mm) square or 1 ⁄8 in. (28.6 mm) round, or
table under 8.4.1.2 considering the distance-amplitude correc-
barium titanate ⁄4 in. (19.1 mm) to 1 in. round.The transducer
tion as described in 8.4.3.
typeisattheoptionoftheaxlemanufacturer.Othertransducers
8.6 Marking—Axles that meet the ultrasonic inspection
of similar response capability as those described may be used.
requirements of this specification shall be stamped with the
8.3 Time of Inspection—Inspection shall be made after heat
letter “T” on the end face adjacent to the heat number or serial
treatment and after the axle ends are machined and centered, or
number.
at any subsequent stage of processing.
8.7 Additional Information:
8.4 Instrument Sensitivity and Scanning:
8.7.1 Alternative Reference Standards— Alternative refer-
8.4.1 Instrument Sensitivity:
ences may be used to establish the test sensitivity if they are
8.4.1.1 The instrument sensitivity shall be adjusted to pro-
cross referenced with the reference test block described in
duce an indication of 20 % full screen height (FSH) from a
8.4.1.1. For example, alternative references for quenched and
reference test block manufactured from a quench and tempered
tempered axles that give equivalent sensitivity: (1) a 1-in.
axle forging having a ⁄8-in. (3.18-mm) diameter, 1 in. (25.4
(25.4-mm) indication from a No. 1 series “A”Alcoa block, and
mm) deep, flat-bottomed hole drilled perpendicularly to and at
(2)a1 ⁄2-in. (38.1-mm) indication from an ASTM Practice
a distance of 15 in. (381 mm) from the test end face of the axle
E 127 (latest edition) block No. 1-0300.
section. The reference blocks shall have a surface finish of 80
8.7.2 Distance-Amplitude Correction—The amplitude of
to 125 µin. (2.03 to 3.18 µm).
an ultrasonic indication from a given discontinuity size varies
8.4.1.2 At the sensitivity established in 8.4.1.1 the instru-
with its distance from the test surface. To compensate for this
ment shall detect in reference axles a flat-bottom hole of the
effect, a distance-amplitude relationship is employed. The
size and distance specified in the table below.
relationship can be established by an electronic device or by
Minimum Size (Flat-Bottom Holes) Detectable at Various
...
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