ASTM A729/A729M-09(2014)

Standard Specification for Alloy Steel Axles, Heat-Treated, for Mass Transit and Electric Railway Service

ABSTRACT
This specification deals with the standard requirements for heat-treated alloy steel axles and solid design roller bearing axles with machined bodies for mass transit and commuter cars in electric and locomotive hauled railway service. Various axle designs are used for this service including motor and non-motor with either inboard or outboard journals. Materials shall be forged, cooled and heat treated by normalizing, liquid quenching, tempering, and straightening. Steels shall conform to chemical composition requirements specified for each of the seven classes considered here. Conformance to mechanical property requirements such as tensile strength, yield strength, elongation, and reduction of area, shall be evaluated by tensile tests. Details of nondestructive ultrasonic and magnetic particle examination procedures are discussed thoroughly. Final axle products shall conform to purchaser-specified size, shape, and finish. Rough machining shall be free of excessively rough ridges and coarse chatter marks, and the finish machined axle surfaces shall be free of injurious imperfections.
SCOPE
1.1 This specification covers heat-treated alloy steel axles for mass transit and commuter cars in electric and locomotive hauled 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 non-motor with either inboard or outboard journals.  
1.4 Supplementary requirements including those in the general requirements of Specification A788/A788M 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 Unless the order specifies the applicable “M” specification designation, the axles shall be furnished to the inch-pound units.  
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

General Information

• Status: Historical
• Publication Date: 30-Sep-2014
• ICS: 45.040 - Materials and components for railway engineering
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.06 - Steel Forgings and Billets

Relations

• Replaces: ASTM A729/A729M-09e1 - Standard Specification for Alloy Steel Axles, Heat-Treated, for Mass Transit and Electric Railway Service
• Effective Date: 01-Oct-2014
• Replaced By: ASTM A729/A729M-15 - Standard Specification for Carbon and Alloy Steel Axles, Heat-Treated, for Mass Transit and Electric Railway Service
• Effective Date: 15-May-2015
• Referred By: ASTM A788/A788M-23 - Standard Specification for Steel Forgings, General Requirements
• Effective Date: 01-Oct-2014

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: A729/A729M −09(Reapproved 2014)
Standard Specification for
Alloy Steel Axles, Heat-Treated, for Mass Transit and
Electric Railway Service
This standard is issued under the fixed designationA729/A729M; 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 A788/A788M Specification for Steel Forgings, General Re-
quirements
1.1 This specification covers heat-treated alloy steel axles
E112 Test Methods for Determining Average Grain Size
for mass transit and commuter cars in electric and locomotive
E381 Method of Macroetch Testing Steel Bars, Billets,
hauled railway service.
Blooms, and Forgings
1.2 This specification is for solid design roller bearing axles
E1426 Test Method for Determining the Effective Elastic
with machined bodies.
Parameter for X-Ray Diffraction Measurements of Re-
sidual Stress
1.3 Various axle designs are used for this service including
motor and non-motor with either inboard or outboard journals.
2.2 Other Standards:
AAR Manual of Standards and Recommended Prac-
1.4 Supplementary requirements including those in the gen-
eral requirements of Specification A788/A788M are provided tices Wheels and Axles
for use when additional testing or inspection is desired. These
shall apply only when specified individually by the purchaser 3. Ordering Information
in the order.
3.1 Material supplied to this specification shall conform to
1.5 Unless the order specifies the applicable “M” specifica- the requirements of Specification A788/A788M, which out-
lines ordering information, manufacturing requirements, test-
tion designation, the axles shall be furnished to the inch-pound
units. ing and retesting methods and procedures, marking,
certification,productanalysisvariations,andadditionalsupple-
1.6 The values stated in either SI units or inch-pound units
mentary requirements.
are to be regarded separately as standard. The values stated in
3.1.1 If the requirements of this specification are in conflict
each system may not be exact equivalents; therefore, each
with the requirements of Specification A788/A788M, then the
system shall be used independently of the other. Combining
requirements of this specification shall prevail.
values from the two systems may result in non-conformance
with the standard. 3.2 In addition to the ordering information required by
Specification A788/A788M, the purchaser should include with
2. Referenced Documents
the inquiry and order a detailed drawing, sketch or written
description of the axle showing complete details pertaining to
2.1 ASTM Standards:
dimensions, tolerances if more restrictive than those contained
A29/A29M SpecificationforGeneralRequirementsforSteel
in this specification, degree of finish, and location of stamping.
Bars, Carbon and Alloy, Hot-Wrought
3.2.1 Unlessthepurchaserdesignatesaclassinthepurchase
A275/A275M Practice for Magnetic Particle Examination of
order or contract, the class used shall be at the producer’s
Steel Forgings
discretion.
A388/A388M Practice for Ultrasonic Examination of Steel
Forgings
3.3 Supplementary requirements, if needed, including any
that are appropriate from Specification A788/A788M.
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
4. Chemical Requirements
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
4.1 Chemical Composition—The steel shall conform to the
Current edition approved Oct. 1, 2014. Published October 2014. Originally
ϵ1
chemical requirements specified in Table 1.
approved in 1976. Last previous edition approved in 2009 as A729/A729M – 09 .
DOI: 10.1520/A0729_A0729M-09R14.
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’s Document Summary page on Available from Association of American Railroads (AAR), 425 Third St., SW,
the ASTM website. Washington, DC 20024, http://www.aar.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
A729/A729M − 09 (2014)
TABLE 1 Chemical Requirements
Composition %
A
Class A Class B Class C Class D Class F ClassesG&H
Carbon 0.43-0.48 0.28-0.33 0.38-0.43 0.28-0.33 0.45-0.59 .
Manganese 0.75-1.00 0.40-0.60 0.75-1.00 0.70 0.90 0.60-0.90 0.60-0.90
Phosphorous 0.035 max 0.035 max 0.035 max 0.035 max 0.035 max 0.035 max
Sulfur 0.040 max 0.040 max 0.040 max 0.040 max 0.040 max 0.040 max
Silicon 0.15-0.35 0.15-0.35 0.15-0.35 0.15-0.35 0.15 min 0.15 min
BB
Nickel . . . 0.40-0.70
BB
Chromium 0.20-0.35 0.80-1.10 0.80-1.10 0.40-0.60
BB
Molybdenum . 0.15-0.25 0.15-0.25 0.15-0.25
BB
Vanadium 0.08 max 0.08 max 0.08 max 0.08 max
BB
Aluminum 0.04 max 0.04 max 0.04 max 0.04 max
A
Class D meets the requirements of SAE 8630 alloy steel.
B
The manufacturer may add these elements as necessary to meet the specified mechanical properties after the required heat treatment. The actual chemistry shall be
reported.
4.2 Seven classes of steel are included in Table 1. Unless 5.3.2 Grades A and F shall be heat-treated by double
otherwisespecifiedbythepurchaser,thechoiceofsteelclassto normalizing, followed by tempering. After heating to and
be used for any given axle grade is at the option of the holding at an appropriate temperature in the austenitic range,
producer. the axles shall be cooled in still air to under 500°F [260°C].
They shall then be reheated into the austenitic range to the
4.3 Classes F, G, and H are referenced in the AAR Manual
same or a lower temperature and again air cooled to under
of Standards and Recommended Practices and unspecified
500°F [260°C]. A furnace charge thus treated is termed a
element additions to these classes shall be reported.
double normalizing charge. After cooling, the axles are then
4.4 The purchaser may use the requirements of Specifica-
tempered as in 5.3.4.
tion A788/A788M for a product analysis.
5.3.3 All other Grades shall be liquid quenched and tem-
pered. After heating to and holding at an appropriate tempera-
5. Manufacture
ture in the austenitic range, the axles shall be quenched in a
5.1 Forging Practice—The axle may be made direct from
suitable medium. A furnace charge thus treated is termed a
the ingot or from blooms, the total reduction in cross-sectional
quenching charge. Following quenching, the axles are tem-
area from ingot or strand cast blooms to axle forging being not
pered as in 5.3.4.
less than 3 to 1, unless otherwise specified.
5.3.3.1 Grade H axles require a normalizing cycle prior to
5.2 Cooling and Heating:
the quenching heat treatment.
5.2.1 Blooms shall be reheated for forging in a manner that
5.3.3.2 At the manufacturer’s option for Grade G, a normal-
will prevent internal bursts and overheating.
izing cycle may precede austenitizing for the liquid quenching
5.2.2 Axles that are heat-treated directly from forging shall
operation.
be cooled below the transformation temperature to at least
5.3.4 Tempering—Axles shall be reheated gradually to and
1000°F [538°C] before any reheating operation.
heldatanappropriatesubcriticaltemperature,andshallthenbe
5.3 Heat Treatment: allowed to cool under uniform conditions. A furnace charge
5.3.1 Axlesshallbeheat-treatedinaccordancewithTable2. thus treated is termed a tempering charge.
TABLE 2 Heat Treatment and Tensile Requirements
Yield Strength
Size, Solid Diameter or Thickness, in. Tensile Strength, Elongation, in Reduction of
Grade Heat Treatment @ 0.2 %, min,
[mm] psi [MPa], min 2 in. [50 mm], min Area %, min
psi [MPa]
Over Not Over
A, F Double Normalize . 8 [200] 88 000 [605] 50 000 [345] 22 37
and Temper 86 000 [595] 48 000 [330] 21 35
8 [200] 12 [300]
... 4 [100] 105 000 [725] 70 000 [485] 24 45
Quench 4 [100] 7 [175] 100 000 [690] 65 000 [450] 22 45
B, C, D
and Temper 7 [175] 10 [250] 85 000 [585] 50 000 [345] 20 40
10 [250] . 82 500 [570] 48 000 [330] 19 35
... 4 [200] 90 000 [620] 55 000 [380] 20 39
Quench
G 4 [100] 7 [175] 85 000 [585] 50 000 [345] 20 39
and Temper
7 [175] 10 [250] 85 000 [585] 50 000 [345] 19 37
Normalize, Quench, . 7 [175] 115 000 [795] 75 000 [520] 16 35
H
and Temper 7 [175] 10 [250] 105 000 [725] 65 000 [450] 18 35
A729/A729M − 09 (2014)
5.3.4.1 When required by supplementary requirement S2, 7.2.2 If axles with prolongations have been expended, then
axles that have been rough machined after heat treatment shall axles may be used for test procurement.
be heated to and held for an appropriate time at a temperature
7.3 Number of Tests:
that is less than the last tempering temperature by at least 50°F
7.3.1 Unless otherwise specified by the purchaser, mechani-
[10°C]. Then the axles shall be quenched directly into water
cal tests shall be made as covered in 7.3.2 and 7.3.3.
with the axle length vertical.
7.3.2 Where batch-type furnaces are used, one test per heat
5.3.5 Heat treatment may be performed in either batch-type
per size classification is required, but each test shall represent
furnaces or continuous furnaces.
no more than 70 axles. The axles represented by this test shall
5.4 Straightening—Straightening, if necessary, shall be
be called a heat-treatment lot.
done before machining and preferably at a temperature not
7.3.3 Where continuous heat-treating furnaces are used, one
lower than 950°F [510°C]. Straightening, performed at tem-
test per heat per size classification is required, but each test
peratureslowerthan950°F[510°C],shallbefollowedbystress
shall represent no more than 70 axles.The axles represented by
relieving or applicable heat treatment.
this test shall be called a heat-treatment lot.
7.4 Retest:
6. Metallurgical Requirements
7.4.1 If the results of the mechanical tests of any lot do not
6.1 A specimen, representing each heat in each heat-
conform to the requirements specified, the axles may be
treatment lot, shall be taken for the heat treated grain size
retreated, but not more than three additional times and retests
determination in accordance with Test Methods E112. This
shall be made in accordance with Section 7.
samplesectionmaybecutfromthelargeundistortedportionof
the tension test specimen in such a way as will give a face
8. Nondestructive Testing Requirements
transverse to the axis of the axle.
8.1 Ultrasonic Examination—The purpose of this examina-
6.2 The entire specimen shall show a uniform, fine-grained
tion is to evaluate the quality of new axles (1) by determining
structure of No. 5 or finer as measured in accordance with Test
end face to end face penetrability, and (2) by detecting
Methods E112.
discontinuities that may be harmful to axle service.
6.3 Alternatively, the austenitic fine grain requirements of
8.2 Method—The axle examination shall conform to Prac-
Specification A29/A29M may be used in lieu of the heat-
tice A388/A388M.
treated grain size described in 6.1. In this case, the grain
8.3 Time of Examination—Examination shall be made after
refining elements used shall be included in the heat analysis
results. heat treatment and after the axle end faces have been machined
square, and preferably before being centered.
7. Tension Test Requirements
8.4 Instrument Sensitivity and Scanning:
7.1 Tensiontestsshallbetakenfromthetestprolongationor
8.4.1 Instrument Sensitivity:
from an axle in accordance with 7.2.
8.4.1.1 The instrument sensitivity shall be adjusted to pro-
7.1.1 Axles shall conform to the requirements in Table 2.
duce an indication of 20 % full screen height (FSH) from a
7.1.2 The diameter of the test prolongation of axle forgings
reference test block manufactured from a representative heat-
shall be determined by the forged diameter of the journal.
treated axle forging having a ⁄8-in. [3.20-mm] diameter, 1 in.
7.1.3 Tests shall be made only after final heat treatment.
[25.4 mm] deep, flat-bottomed hole drilled perpendicularly to
7.1.4 The longitudinal axis of the specimen shall be located
and at a distance of 15 in. [381 mm] from the test end face of
at any point midway between the center and surface of the axle
the axle section. The reference blocks shall have a surface
orfull-sizedprolongationandshallbeparalleltotheaxisofthe
finish of 80 to 125 µin. [2.03 to 3.20 µm] and detect in
axle.
reference axles a flat-bottom hole of the size and distance
specified in the table below.
7.2 Prolongation:
7.2.1 To ensure that sufficient material is available for test 8.4.1.2 At the sensitivity established in 8.4.1.1, the instru-
purposes, prolongations shall be attached to at least 5 % of the ment shall be capable of detecting a flat bottom hole of the size
axles in each heat in each heat-treating lot. and distance specified below:
FIG. 1 Typical Distance-Amplitude Curve for a Heat-Treated Axle Using a 1 ⁄8-in. [28.6-mm] Diameter 2.25-MHz Quartz Transducer
A729/A729M − 09 (2014)
FIG. 2 Location of Reference Holes in an Axle—Flat Bottom Hole Sizes for a Heat-Treated Axle
8.7.1 AmplitudeCorrection—Theamplitudeofanultrasonic
Minimum Size (Flat-Bottom Holes) Detectable at Various Distances
from End Faces
indication from a given discontinuity size varies with its
distance from the test surface. To compensate for this effect, a
Test Distance to 15 Test Distance 15 to 30 in. Test Distance over
in. [381 mm] [381 to 762 mm] 30 in. [762 mm] distance-amplitude relationship is employed. The relationship
1 1 3
⁄8 in. ⁄4 in. ⁄8 in.
can be established by an electronic device or by curves.
[3.20 mm] [6.35 mm] [9.52 mm]
Because the distance-amplitude relationship is influenced pri-
8.4.2 Scanning:
marily by the ultrasonic transducer and instrument, it is
8.4.2.1 Scanning shall be performed from both end faces,
necessary to relate this factor to the specific equipment used.
which shall have a surface finish of 125 µin. [3.20 µm]
Appropriate distance-amplitude curves shall be developed. A
maximum and, when specified, from the outside diameter
typical example is shown in Fig. 1 as related to the axle in Fig.
(OD). The scanning shall include the maximum end face area
2.
obtainable by manual or automated inspection techniques.
8.7.2 Spurious Ultrasonic Indications from Contour
8.4.2.2 During scanning the amplitude of the indication
Variations—Because an axle varies in cross section it is
from the end face opposite the search unit shall be monitored
possible to produce spurious indications, particularly at
a
...

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.
´1
Designation: A729/A729M − 09 A729/A729M − 09 (Reapproved 2014)
Standard Specification for
Alloy Steel Axles, Heat-Treated, for Mass Transit and
Electric Railway Service
This standard is issued under the fixed designation A729/A729M; 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.
ε NOTE—Editorially corrected 8.4.2.1 and 8.5.3 in October 2011.
1. Scope*Scope
1.1 This specification covers heat-treated alloy steel axles for mass transit and commuter cars in electric and locomotive hauled
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 non-motor with either inboard or outboard journals.
1.4 Supplementary requirements including those in the general requirements of Specification A788/A788M 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 Unless the order specifies the applicable “M” specification designation, the axles shall be furnished to the inch-pound units.
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
2. Referenced Documents
2.1 ASTM Standards:
A29/A29M Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A788/A788M Specification for Steel Forgings, General Requirements
E112 Test Methods for Determining Average Grain Size
E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
E1426 Test Method for Determining the Effective Elastic Parameter for X-Ray Diffraction Measurements of Residual Stress
2.2 Other Standards:
AAR Manual of Standards and Recommended Practices Wheels and Axles
3. Ordering Information
3.1 Material supplied to this specification shall conform to the requirements of Specification A788/A788M, which outlines
ordering information, manufacturing requirements, testing and retesting methods and procedures, marking, certification, product
analysis variations, and additional supplementary requirements.
3.1.1 If the requirements of this specification are in conflict with the requirements of Specification A788/A788M, then the
requirements of this specification shall prevail.
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06
on Steel Forgings and Billets.
Current edition approved April 1, 2009Oct. 1, 2014. Published April 2009October 2014. Originally approved in 1976. Last previous edition approved in 20062009 as
ϵ1
A729/A729M – 06.A729/A729M – 09 . DOI: 10.1520/A0729_A0729M-09E01.10.1520/A0729_A0729M-09R14.
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’s Document Summary page on the ASTM website.
Available from the Association of American Railroads, http://www.aarpublications.com/. Railroads (AAR), 425 Third St., SW, Washington, DC 20024, http://
www.aar.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
A729/A729M − 09 (2014)
3.2 In addition to the ordering information required by Specification A788/A788M, the purchaser should include with the
inquiry and order a detailed drawing, sketch or written description of the axle showing complete details pertaining to dimensions,
tolerances if more restrictive than those contained in this specification, degree of finish, and location of stamping.
3.2.1 Unless the purchaser designates a class in the purchase order or contract, the class used shall be at the producer’s
discretion.
3.3 Supplementary requirements, if needed, including any that are appropriate from Specification A788/A788M.
4. Chemical Requirements
4.1 Chemical Composition—The steel shall conform to the chemical requirements specified in Table 1.
4.2 Seven classes of steel are included in Table 1. Unless otherwise specified by the purchaser, the choice of steel class to be
used for any given axle grade is at the option of the producer.
4.3 Classes F, G, and H are referenced in the AAR Manual of Standards and Recommended Practices and unspecified element
additions to these classes shall be reported.
4.4 The purchaser may use the requirements of Specification A788/A788M for a product analysis.
5. Manufacture
5.1 Forging Practice—The axle may be made direct from the ingot or from blooms, the total reduction in cross-sectional area
from ingot or strand cast blooms to axle forging being not less than 3 to 1, unless otherwise specified.
5.2 Cooling and Heating:
5.2.1 Blooms shall be reheated for forging in a manner that will prevent internal bursts and overheating.
5.2.2 Axles that are heat-treated directly from forging shall be cooled below the transformation temperature to at least 1000°F
[538°C] before any reheating operation.
5.3 Heat Treatment:
5.3.1 Axles shall be heat-treated in accordance with Table 2.
5.3.2 Grades A and F shall be heat-treated by double normalizing, followed by tempering. After heating to and holding at an
appropriate temperature in the austenitic range, the axles shall be cooled in still air to under 500°F [260°C]. They shall then be
reheated into the austenitic range to the same or a lower temperature and again air cooled to under 500°F [260°C]. A furnace charge
thus treated is termed a double normalizing charge. After cooling, the axles are then tempered as in 5.3.4.
5.3.3 All other Grades shall be liquid quenched and tempered. After heating to and holding at an appropriate temperature in the
austenitic range, the axles shall be quenched in a suitable medium. A furnace charge thus treated is termed a quenching charge.
Following quenching, the axles are tempered as in 5.3.4.
5.3.3.1 Grade H axles require a normalizing cycle prior to the quenching heat treatment.
5.3.3.2 At the manufacturer’s option for Grade G, a normalizing cycle may precede austenitizing for the liquid quenching
operation.
5.3.4 Tempering—Axles shall be reheated gradually to and held at an appropriate subcritical temperature, and shall then be
allowed to cool under uniform conditions. A furnace charge thus treated is termed a tempering charge.
5.3.4.1 When required by supplementary requirement S2, axles that have been rough machined after heat treatment shall be
heated to and held for an appropriate time at a temperature that is less than the last tempering temperature by at least 50°F [10°C].
Then the axles shall be quenched directly into water with the axle length vertical.
5.3.5 Heat treatment may be performed in either batch-type furnaces or continuous furnaces.
TABLE 1 Chemical Requirements
Composition %
A
Class A Class B Class C Class D Class F Classes G & H
Carbon 0.43-0.48 0.28-0.33 0.38-0.43 0.28-0.33 0.45-0.59 .
Manganese 0.75-1.00 0.40-0.60 0.75-1.00 0.70 0.90 0.60-0.90 0.60-0.90
Phosphorous 0.035 max 0.035 max 0.035 max 0.035 max 0.035 max 0.035 max
Sulfur 0.040 max 0.040 max 0.040 max 0.040 max 0.040 max 0.040 max
Silicon 0.15-0.35 0.15-0.35 0.15-0.35 0.15-0.35 0.15 min 0.15 min
B B
Nickel . . . 0.40-0.70
B B
Chromium 0.20-0.35 0.80-1.10 0.80-1.10 0.40-0.60
B B
Molybdenum . 0.15-0.25 0.15-0.25 0.15-0.25
B B
Vanadium 0.08 max 0.08 max 0.08 max 0.08 max
B B
Aluminum 0.04 max 0.04 max 0.04 max 0.04 max
A
Class D meets the requirements of SAE 8630 alloy steel.
B
The manufacturer may add these elements as necessary to meet the specified mechanical properties after the required heat treatment. The actual chemistry shall be
reported.
A729/A729M − 09 (2014)
TABLE 2 Heat Treatment and Tensile Requirements
Yield Strength
Size, Solid Diameter or Thickness, in. Tensile Strength, Elongation, in Reduction of
Grade Heat Treatment @ 0.2 %, min,
[mm] psi [MPa], min 2 in. [50 mm], min Area %, min
psi [MPa]
Over Not Over
A, F Double Normalize . 8 [200] 88 000 [605] 50 000 [345] 22 37
and Temper
86 000 [595] 48 000 [330] 21 35
8 [200] 12 [300]
... 4 [100] 105 000 [725] 70 000 [485] 24 45
Quench 4 [100] 7 [175] 100 000 [690] 65 000 [450] 22 45
B, C, D
and Temper 7 [175] 10 [250] 85 000 [585] 50 000 [345] 20 40
10 [250] . 82 500 [570] 48 000 [330] 19 35
... 4 [200] 90 000 [620] 55 000 [380] 20 39
Quench
G 4 [100] 7 [175] 85 000 [585] 50 000 [345] 20 39
and Temper
7 [175] 10 [250] 85 000 [585] 50 000 [345] 19 37
Normalize, Quench, . 7 [175] 115 000 [795] 75 000 [520] 16 35
H
and Temper 7 [175] 10 [250] 105 000 [725] 65 000 [450] 18 35
5.4 Straightening—Straightening, if necessary, shall be done before machining and preferably at a temperature not lower than
950°F [510°C]. Straightening, performed at temperatures lower than 950°F [510°C], shall be followed by stress relieving or
applicable heat treatment.
6. Metallurgical Requirements
6.1 A specimen, representing each heat in each heat-treatment lot, shall be taken for the heat treated grain size determination
in accordance with Test Methods E112. This sample section may be cut from the large undistorted portion of the tension test
specimen in such a way as will give a face transverse to the axis of the axle.
6.2 The entire specimen shall show a uniform, fine-grained structure of No. 5 or finer as measured in accordance with Test
Methods E112.
6.3 Alternatively, the austenitic fine grain requirements of Specification A29/A29M may be used in lieu of the heat-treated grain
size described in 6.1. In this case, the grain refining elements used shall be included in the heat analysis results.
7. Tension Test Requirements
7.1 Tension tests shall be taken from the test prolongation or from an axle in accordance with 7.2.
7.1.1 Axles shall conform to the requirements in Table 2.
7.1.2 The diameter of the test prolongation of axle forgings shall be determined by the forged diameter of the journal.
7.1.3 Tests shall be made only after final heat treatment.
7.1.4 The longitudinal axis of the specimen shall be located at any point midway between the center and surface of the axle or
full-sized prolongation and shall be parallel to the axis of the axle.
7.2 Prolongation:
7.2.1 To ensure that sufficient material is available for test purposes, prolongations shall be attached to at least 5 % of the axles
in each heat in each heat-treating lot.
7.2.2 If axles with prolongations have been expended, then axles may be used for test procurement.
7.3 Number of Tests:
7.3.1 Unless otherwise specified by the purchaser, mechanical 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 per size classification is required, but each test shall represent no
more than 70 axles. The axles represented by this test shall be called a heat-treatment lot.
FIG. 1 Typical Distance-Amplitude Curve for a Heat-Treated Axle Using a 1 ⁄8-in. [28.6-mm] Diameter 2.25-MHz Quartz Transducer
A729/A729M − 09 (2014)
FIG. 2 Location of Reference Holes in an Axle—Flat Bottom Hole Sizes for a Heat-Treated Axle
7.3.3 Where continuous heat-treating furnaces are used, one test per heat per size classification is required, but each test shall
represent no more than 70 axles. The axles represented by this test shall be called a heat-treatment lot.
7.4 Retest:
7.4.1 If the results of the mechanical tests of any lot do not conform to the requirements specified, the axles may be retreated,
but not more than three additional times and retests shall be made in accordance with Section 7.
8. Nondestructive Testing Requirements
8.1 Ultrasonic Examination—The purpose of this examination is to evaluate the quality of new axles (1) by determining end
face to end face penetrability, and (2) by detecting discontinuities that may be harmful to axle service.
8.2 Method—The axle examination shall conform to Practice A388/A388M.
8.3 Time of Examination—Examination shall be made after heat treatment and after the axle end faces have been machined
square, and preferably before being centered.
8.4 Instrument Sensitivity and Scanning:
8.4.1 Instrument Sensitivity:
8.4.1.1 The instrument sensitivity shall be adjusted to produce an indication of 20 % full screen height (FSH) from a reference
test block manufactured from a representative heat-treated axle forging having a ⁄8-in. [3.20-mm] diameter, 1 in. [25.4 mm] deep,
flat-bottomed hole drilled perpendicularly to and at a distance of 15 in. [381 mm] from the test end face of the axle section. The
reference blocks shall have a surface finish of 80 to 125 μin. [2.03 to 3.20 μm] and detect in reference axles a flat-bottom hole of
the size and distance specified in the table below.
8.4.1.2 At the sensitivity established in 8.4.1.1, the instrument shall be capable of detecting a flat bottom hole of the size and
distance specified below:
Minimum Size (Flat-Bottom Holes) Detectable at Various Distances
from End Faces
Test Distance to 15 Test Distance 15 to 30 in. Test Distance over
in. [381 mm] [381 to 762 mm] 30 in. [762 mm]
1 1 3
⁄8 in. ⁄4 in. ⁄8 in.
[3.20 mm] [6.35 mm] [9.52 mm]
8.4.2 Scanning:
8.4.2.1 Scanning shall be performed from both end faces, which shall have a surface finish of 125 μin. [3.20 μm] maximum and,
when specified, from the outside diameter (OD). The scanning shall include the maximum end face area obtainable by manual or
automated inspection techniques.
8.4.2.2 During scanning the amplitude of the indication from the end face opposite the search unit shall be monitored and the
amplitudes of all discontinuity indications shall be evaluated with respect to the distance from the test surface (see 8.4.3 and 8.7.2).
8.4.3 Distance-Amplitude Correction—The amplitude of an ultrasonic indication must be
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