1、Designation: A729/A729M 151Standard Specification forCarbon and Alloy Steel Axles, Heat-Treated, for Mass Transitand Electric Railway Service1This standard is issued under the fixed designation A729/A729M; the number immediately following the designation indicates the yearof original adoption or, in
2、 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.1NOTEFigs. 1 and 2 were corrected editorially in December 2015.1. Scope*1.1 This specification
3、covers heat-treated carbon and alloysteel axles for mass transit and commuter cars in electric andlocomotive hauled railway service.1.2 This specification is for solid design roller bearing axleswith machined bodies.1.3 Various axle designs are used for this service includingmotor and non-motor with
4、 either inboard or outboard journals.1.4 Supplementary requirements including those in the gen-eral requirements of Specification A788/A788M are providedfor use when additional testing or inspection is desired. Theseshall apply only when specified individually by the purchaserin the order.1.5 Unless
5、 the order specifies the applicable “M” specifica-tion designation, the axles shall be furnished to the inch-poundunits.1.6 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, each
6、system shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.2. Referenced Documents2.1 ASTM Standards:2A29/A29M Specification for General Requirements for SteelBars, Carbon and Alloy, Hot-WroughtA275/A275M Practice for Magnetic
7、 Particle Examination ofSteel ForgingsA388/A388M Practice for Ultrasonic Examination of SteelForgingsA788/A788M Specification for Steel Forgings, General Re-quirementsE112 Test Methods for Determining Average Grain SizeE381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and ForgingsE1426 Te
8、st Method for Determining the X-Ray ElasticConstants for Use in the Measurement of Residual StressUsing X-Ray Diffraction Techniques2.2 Other Standards:3AAR Manual of Standards and Recommended Prac-tices Wheels and Axles3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 classthe
9、set of chemical requirements for the steel tobe used for the axles to be supplied.3.1.2 gradethe designation of the specific set of mechani-cal properties selected for the axle(s) to be supplied. The gradeis selected based on the axle design and service requirements.3.2 Users of this specification a
10、re cautioned that the aboveterms may be used differently in other industry standards andpurchaser ordering information. Producers and purchasersshould ensure that both parties are in agreement regarding thespecific mechanical and chemical requirements for the axles tobe supplied.4. Ordering Informat
11、ion4.1 Material supplied to this specification shall conform tothe requirements of Specification A788/A788M, which out-lines ordering information, manufacturing requirements, test-ing and retesting methods and procedures, marking,certification, product analysis variations, and additional supple-ment
12、ary requirements.4.1.1 If the requirements of this specification are in conflictwith the requirements of Specification A788/A788M, then therequirements of this specification shall prevail.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys
13、and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current edition approved May 15, 2015. Published June 2015. Originallyapproved in 1976. Last previous edition approved in 2014 as A729/A729M 09(2014). DOI: 10.1520/A0729_A0729M-15E01.2For referenced ASTM standards,
14、visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Association of American Railroads (AAR), 425 Third St., SW,Washington, DC 200
15、24, http:/www.aar.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 In addition to the ordering information required bySpecification A788/A788M, the purchaser shou
16、ld include withthe inquiry and order a detailed drawing, sketch or writtendescription of the axle showing complete details pertaining todimensions, tolerances if more restrictive than those containedin this specification, degree of finish, and location of stamping.4.2.1 Unless the purchaser designat
17、es a class in the purchaseorder or contract, the class used shall be at the producersdiscretion.4.3 Supplementary requirements, if needed, including anythat are appropriate from Specification A788/A788M.5. Chemical Requirements5.1 Chemical CompositionThe steel shall conform to thechemical requiremen
18、ts specified in Table 1.5.2 Seven classes of steel are included in Table 1. Unlessotherwise specified by the purchaser, the choice of steel class tobe used for any given axle grade is at the option of theproducer.5.3 Classes F, G, and H are referenced in the AAR Manualof Standards and Recommended Pr
19、actices as Grades F, G, andH and unspecified element additions to these classes shall bereported.5.4 The purchaser may use the requirements of Specifica-tion A788/A788M for a product analysis.6. Manufacture6.1 Forging PracticeThe axle may be made direct fromthe ingot or from blooms, the total reduct
20、ion in cross-sectionalarea from ingot or strand cast blooms to axle forging being notless than 3 to 1, unless otherwise specified.6.2 Cooling and Heating:6.2.1 Blooms and ingots shall be reheated for forging in amanner that will prevent internal bursts and overheating.6.2.2 Axles that are heat-treat
21、ed directly from forging shallbe cooled and fully transformed before any reheating opera-tion. The temperature of the axle shall be below 1000F538C before the start of any reheating operation.6.3 Heat Treatment:6.3.1 Axles shall be heat-treated in accordance with Table 2.6.3.2 Grades A and F shall b
22、e heat-treated by doublenormalizing, followed by tempering. After heating to andholding at an appropriate temperature in the austenitic range,the axles shall be cooled in still air to under 500F 260C.They shall then be reheated into the austenitic range to thesame or a lower temperature and again ai
23、r cooled to under500F 260C. A furnace charge thus treated is termed adouble normalizing charge. After cooling, the axles are thentempered as in 6.3.4.6.3.3 All other Grades shall be liquid quenched and tem-pered. After heating to and holding at an appropriate tempera-ture in the austenitic range, th
24、e axles shall be quenched in asuitable medium. A furnace charge thus treated is termed aquenching charge. Following quenching, the axles are tem-pered as in 6.3.4.6.3.3.1 Grade H axles require a normalizing cycle prior tothe quenching heat treatment.6.3.3.2 At the manufacturers option for Grade G, a
25、 normal-izing cycle may precede austenitizing for the liquid quenchingoperation.6.3.4 TemperingAxles shall be reheated gradually to andheld at an appropriate subcritical temperature, and shall then beallowed to cool under uniform conditions. A furnace chargethus treated is termed a tempering charge.
26、6.3.4.1 When required by supplementary requirement S2,axles that have been rough machined after heat treatment shallbe heated to and held for an appropriate time at a temperaturethat is less than the last tempering temperature by at least 50F10C. Then the axles shall be quenched directly into waterw
27、ith the axle length vertical.6.3.5 Heat treatment may be performed in either batch-typefurnaces or continuous furnaces.6.4 StraighteningStraightening, if necessary, shall bedone before machining and at a temperature between 950F510C and 100F 55C below the final tempering tempera-ture. Straightening
28、performed at temperatures lower than950F 510C shall be followed by stress relieving or appli-cable heat treatment. These requirements do not apply tostraightening performed prior to final heat treatment.TABLE 1 Chemical RequirementsComposition %Class A Class B Class C Class DAClass F ClassesG in the
29、 case of motor axleshaving a conglomerate of diameters for the seats for wheel,gear, gear case bearing, and grounding ring the entire area shallbe rough machined to a single diameter18 to14 in. 3.2 to6.4 mm over the finished diameter of the segment having thelargest diameter. Longitudinally18 to14 i
30、n. 3.2 to 6.4 mm ofmetal shall be allowed at each change of cross section for finishmachining.11.1.6 The smooth-machined body shall be to the specifiedsize with no more than18 in. 3.2 mm over on the diametersand shall have no more than18 in. 3.2 mm allowancelongitudinally at each change of cross sec
31、tion.12. Workmanship and Finish12.1 Axles shall conform to the size, shape, and finishshown on the purchasers drawing and unless otherwisespecified shall have center holes with clearance drilled for lathecenter points and not counter bored. All machining shall bedone in a workmanlike manner.12.2 Whe
32、re a smooth-machined finish on the body (11.1.6)is specified, it shall be to a maximum of 250 in. 6.35 m.Rough machining shall be free of excessively rough ridges andcoarse chatter marks.12.3 Finish machined axle surfaces shall be free of injuriousimperfections as defined in Annex A1.13. Product Mar
33、king13.1 In addition to the marking requirements of Specifica-tion A788/A788M, axles shall be legibly cold-stamped withletters and figures not less than14 in. 6.4 mm high. Thisstamping shall be on the end face or under cut shoulder at theend of the journal as shown on the purchasers drawing. Itshoul
34、d include month and year made, manufacturers name ortrademark, heat number, and serial number.13.2 In addition to the above required markings, bar codetags may be applied to the axles. If these tags are applied, it isrecommended that Bar Code 39 for 1-D bar code labels orAAR S-920 for 2-D bar code l
35、abels be used. The size andlocation of the tags, as well as the information to be included,shall be agreed upon by the purchaser and the manufacturer.14. Keywords14.1 axles; rail applications; steel forgingsSUPPLEMENTARY REQUIREMENTSThe following supplementary requirement shall apply only when speci
36、fied by the purchaser. Detailsshall be agreed upon by the manufacturer and the purchaser.S1. Macroscopical TestsS1.1 The prolongation from the largest axle in each heatshall be sawed normal to the axis of the axle and shall then besplit longitudinally. The transverse and the longitudinal facesshall
37、be etched for macro examination in accordance withMethod E381.S1.2 Acceptance criteria shall be based on the adjuncts ofMethod E381 as specified in the purchase order.S2. Accelerated Cooling after Stress ReliefS2.1 When specified, the rough machined axle shall begiven a sub-critical quench from a te
38、mperature above 900F480C. Sufficient allowance shall be left in the rough ma-chined billet so that the axle can be machined to finaldimensions after sub-critical quench.S3. Residual Stress MeasurementS3.1 When specified, the residual compressive stresses shallbe measured in the body section of one r
39、epresentative axle.X-ray diffraction residual stress measurements to Test MethodE1426 shall be considered the standard method.S3.2 The results shall be reported.A729/A729M 1515ANNEX(Mandatory Information)A1. INTERPRETATION OF IMPERFECTIONS CONSIDERED INJURIOUS IN AXLESA1.1 GeneralA1.1.1 The conditio
40、ns that have been most difficult forinspectors to evaluate are light lines visible to the normalunaided eye, variously described as actual seams, hairlines,stringers, shadow seams, ghost lines, and so forth, whichappear after the axles have been finish machined and burnishedor ground. It is, therefo
41、re, advisable to describe these condi-tions in more detail.A1.1.2 The interpretation of injurious imperfections as enu-merated below is not to be considered as precluding otherunforeseen or objectionable conditions not specifically listed.The right of the purchaser is reserved to reject temporarily
42、suchaxles and make final settlement on the basis of furthernegotiations between representatives of the manufacturer andthe purchaser who are especially qualified to decide suchquestions.A1.1.3 Any transverse or circumferential seams, cracks, orlaps of indeterminate depth on the axle surfaces other t
43、han thediscolorations listed in A1.1.4 regardless of their location, areconsidered to be injurious and are cause for rejection withoutfurther machining.A1.1.4 Ghost lines, shadow marks, or other similardiscolorations, visible to the normal unaided eye that are notactual separations in the metal are
44、not considered injuriousregardless of location.A1.1.5 Any longitudinal discontinuity, variously termedhairline, stringer, or fine seam, in machined fillets is consideredto be injurious and is cause for rejection without furtherconditioning.A1.2 Journals and Dust GuardsA1.2.1 Fine longitudinal discon
45、tinuities on the finished(burnished or ground) surfaces variously termed hairlines,stringers, or fine seams are not considered injurious if theymeet the following conditions:A1.2.1.1 Must not extend into fillets.A1.2.1.2 Must not be over34 in. 20 mm long individuallyin the journal nor12 in. 12.7 mm
46、long individually in thedust-guard seat.A1.2.1.3 Total length of such imperfections over14 in.6.4 mm long must not exceed 2 in. 50.8 mm in any one endof the axle.A1.3 Wheel Seats, Gear Seats, Gear Case Bearing Seat,and Grounding Ring SeatsA1.3.1 Longitudinal discontinuities on the finished-machined
47、surface of wheel and gear seats, variously termedhairlines, stringers, fine seams, tight seams, surfaceimperfections, and so forth, are not considered injurious if theymeet the following conditions:A1.3.1.1 Must not extend within 112 in. 38.1 mm of eitherend of the seats covered in this section.A1.3
48、.1.2 Must not be over12 in. 12.7 mm long individu-ally.A1.3.1.3 Total length of such imperfections,14 in. 6.4 mmto12 in. 12.7 mm long, must not exceed 3 in. 76.2 mm inany one end of the axle.A1.4 Areas Between Attachment Seats (Body) Specified toBe Smooth MachinedA1.4.1 Longitudinal discontinuities
49、on the smooth ma-chined body, variously termed hairlines, stringers, or fineseams, are not considered injurious if they meet the followingconditions:A1.4.1.1 Must not extend into fillets at the ends of the body,A1.4.1.2 Must not be over12 in. 12.7 mm longindividually,A1.4.1.3 Total length of such imperfections,14 in. 6.4 mmto12 in. 12.7 mm long, must not exceed 112 in. 38.1 mm inany 12 in. 305 mm of body length, andA1.4.1.4 Axles containing longitudinal discontinuities inthe b
