1、Designation: A 729/A 729M 09Standard Specification forAlloy Steel Axles, Heat-Treated, for Mass Transit andElectric Railway Service1This standard is issued under the fixed designationA 729/A 729M; the number immediately following the designation indicates the yearof original adoption or, in the case
2、 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*1.1 This specification covers heat-treated alloy steel axlesfor mass transit and commuter cars
3、in electric and locomotivehauled 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 either inboard or outboard journals.1.4 Supplementary requirements including those
4、 in the gen-eral requirements of Specification A 788/A 788M are providedfor use when additional testing or inspection is desired. Theseshall apply only when specified individually by the purchaserin the order.1.5 Unless the order specifies the applicable “M” specifica-tion designation, the axles sha
5、ll 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, eachsystem shall be used independently of the other. Combiningvalues from the two sys
6、tems may result in non-conformancewith the standard.2. Referenced Documents2.1 ASTM Standards:2A 29/A 29M Specification for Steel Bars, Carbon andAlloy,Hot-Wrought, General Requirements forA 275/A 275M Practice for Magnetic Particle Examinationof Steel ForgingsA 388/A 388M Practice for Ultrasonic Ex
7、amination ofSteel ForgingsA 788/A 788M Specification for Steel Forgings, GeneralRequirementsE112 Test Methods for Determining Average Grain SizeE 381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and ForgingsE 1426 Test Method for Determining the Effective ElasticParameter for X-Ray Diffra
8、ction Measurements of Re-sidual Stress2.2 Other Standards:AAR Manual of Standards and Recommended Practices-Wheels and Axles33. Ordering Information3.1 Material supplied to this specification shall conform tothe requirements of Specification A 788/A 788M, which out-lines ordering information, manufa
9、cturing requirements, test-ing and retesting methods and procedures, marking, certifica-tion, product analysis variations, and additional supplementaryrequirements.3.1.1 If the requirements of this specification are in conflictwith the requirements of SpecificationA 788/A 788M, then therequirements
10、of this specification shall prevail.3.2 In addition to the ordering information required bySpecification A 788/A 788M, the purchaser should includewith the inquiry and order a detailed drawing, sketch or writtendescription of the axle showing complete details pertaining todimensions, tolerances if m
11、ore restrictive than those containedin this specification, degree of finish, and location of stamping.3.2.1 Unless the purchaser designates a class in the purchaseorder or contract, the class used shall be at the producersdiscretion.3.3 Supplementary requirements, if needed, including anythat are ap
12、propriate from Specification A 788/A 788M.4. Chemical Requirements4.1 Chemical CompositionThe steel shall conform to thechemical requirements specified in Table 1.4.2 Seven classes of steel are included in Table 1. Unlessotherwise specified by the purchaser, the choice of steel class tobe used for a
13、ny given axle grade is at the option of theproducer.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current edition approved April 1, 2009. Published A
14、pril 2009. Originallyapproved in 1976. Last previous edition approved in 2006 as A 729/A 729M 06.2For referenced ASTM standards, 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 Docum
15、ent Summary page onthe ASTM website.3Available from the Association of American Railroads, http:/ 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.4.3 Classes F, G, and H a
16、re referenced in the AAR Manualof Standards and Recommended Practices and unspecifiedelement additions to these classes shall be reported.4.4 The purchaser may use the requirements of Specifica-tion A 788/A 788M for a product analysis.5. Manufacture5.1 Forging PracticeThe axle may be made direct fro
17、mthe ingot or from blooms, the total reduction in cross-sectionalarea from ingot or strand cast blooms to axle forging being notless than 3 to 1, unless otherwise specified.5.2 Cooling and Heating:5.2.1 Blooms shall be reheated for forging in a manner thatwill prevent internal bursts and overheating
18、.5.2.2 Axles that are heat-treated directly from forging shallbe cooled below the transformation temperature to at least1000F 538C 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 doublenormal
19、izing, 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 air cooled to under500F 260C. A
20、furnace charge thus treated is termed adouble normalizing charge. After cooling, the axles are thentempered as in 5.3.4.5.3.3 All other Grades shall be liquid quenched and tem-pered. After heating to and holding at an appropriate tempera-ture in the austenitic range, the axles shall be quenched in a
21、suitable medium. A furnace charge thus treated is termed aquenching charge. Following quenching, the axles are tem-pered as in 5.3.4.5.3.3.1 Grade H axles require a normalizing cycle prior tothe quenching heat treatment.5.3.3.2 At the manufacturers option for Grade G, a normal-izing cycle may preced
22、e austenitizing for the liquid quenchingoperation.5.3.4 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.5.3.4.1 When required by suppl
23、ementary 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 waterwith the axle length vertical.T
24、ABLE 1 Chemical RequirementsComposition %Class A Class B Class C Class DAClass F ClassesG in the 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
25、mm over the finished diameter of the segment having thelargest diameter. Longitudinally18 to14 in. 3.2 to 6.4 mm ofmetal shall be allowed at each change of cross section for finishmachining.10.1.6 The smooth-machined body shall be to the specifiedsize with no more than18 in. 3.2 mm over on the diame
26、tersand shall have no more than18 in. 3.2 mm allowancelongitudinally at each change of cross section.11. Workmanship and Finish11.1 Axles shall conform to the size, shape, and finishshown on the purchasers drawing and unless otherwiseFIG. 2 Location of Reference Holes in an AxleFlat Bottom Hole Size
27、s for a Heat-Treated AxleA 729/A 729M 094specified shall have center holes with clearance drilled for lathecenter points and not counter bored. All machining shall bedone in a workmanlike manner.11.2 Where a smooth-machined finish on the body (10.1.6)is specified, it shall be to a maximum of 250 in.
28、 6.35 m.Rough machining shall be free of excessively rough ridges andcoarse chatter marks.11.3 Finish machined axle surfaces shall be free of injuriousimperfections as defined in Annex A1.12. Product Marking12.1 In addition to the marking requirements of Specifica-tion A 788/A 788M, axles shall be l
29、egibly 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. Itshould include month and year made, manufacturers name ortrademark, heat number, and serial number.1
30、2.2 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 be used. The size and locationof the tags, as well as the information to be included, shall beagreed upon by the purchaser and the manufacturer.13. K
31、eywords13.1 axles; rail applications; steel forgingsSUPPLEMENTARY REQUIREMENTSThe following supplementary requirement shall apply only when specified by the purchaser. Detailsshall be agreed upon by the manufacturer and the purchaser.S1. Macroscopical TestsS1.1 The prolongation from the largest axle
32、 in each heatshall be sawed normal to the axis of the axle and shall then besplit longitudinally. The transverse and the longitudinal facesshall be etched for macro examination in accordance withMethod E 381.S1.2 Acceptance criteria shall be based on the adjuncts ofMethod E 381 as specified in the p
33、urchase order.S2. Accelerated Cooling after Stress ReliefS2.1 When specified, the rough machined axle shall begiven a sub-critical quench from a temperature above 900F480C. Sufficient allowance shall be left in the rough ma-chined billet so that the axle can be machined to finaldimensions after sub-
34、critical quench.S3. Residual Stress MeasurementS3.1 When specified, fee residual compressive stresses shallbe measured in the body section of one representative axle.X-ray diffraction residual stress measurements to Test MethodE 1426 shall be considered the standard method.S3.2 The results shall be
35、reported.ANNEX(Mandatory Information)A1. INTERPRETATION OF IMPERFECTIONS CONSIDERED INJURIOUS IN AXLESA1.1 GeneralA1.1.1 The conditions that have been most difficult forinspectors to evaluate are light lines visible to the normalunaided eye, variously described as actual seams, hairlines,stringers,
36、shadow seams, ghost lines, and so forth, whichappear after the axles have been finish machined and burnishedor ground. It is, therefore, 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 preclud
37、ing otherunforeseen or objectionable conditions not specifically listed.The right of the purchaser is reserved to reject temporarily suchaxles and make final settlement on the basis of furthernegotiations between representatives of the manufacturer andthe purchaser who are especially qualified to de
38、cide suchquestions.A1.1.3 Any transverse or circumferential seams, cracks, orlaps of indeterminate depth on the axle surfaces other than 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 li
39、nes, shadow marks, or other similar discol-orations, visible to the normal unaided eye that are not actualseparations in the metal are not considered injurious regardlessof location.A 729/A 729M 095A1.1.5 Any longitudinal discontinuity, variously termedhairline, stringer, or fine seam, in machined f
40、illets is consideredto be injurious and is cause for rejection without furtherconditioning.A1.2 Journals and Dust GuardsA1.2.1 Fine longitudinal discontinuities on the finished(burnished or ground) surfaces variously termed hairlines,stringers, or fine seams are not considered injurious if theymeet
41、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 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 en
42、dof the axle.A1.3 Wheel Seats, Gear Seats, Gear Case Bearing Seat,and Grounding Ring SeatsA1.3.1 Longitudinal discontinuities on the finished-machined surface of wheel and gear seats, variously termedhairlines, stringers, fine seams, tight seams, surface imperfec-tions, and so forth, are not conside
43、red injurious if they meet thefollowing conditions:A1.3.1.1 Must not extend within 112 in. 38.1 mm of eitherend of the seats covered in this section.A1.3.1.2 Must not be over12 in. 12.7 mm long individu-ally.A1.3.1.3 Total length of such imperfections,14 in.6.4 mm to12 in. 12.7 mm long, must not exc
44、eed 3 in.76.2 mm in any one end of the axle.A1.4 Areas Between Attachment Seats (Body) Specifiedto Be Smooth MachinedA1.4.1 Longitudinal discontinuities on the smooth ma-chined body, variously termed hairlines, stringers, or fineseams, are not considered injurious if they meet the followingcondition
45、s: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 long individu-ally,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
46、longitudinal discontinuities inthe body in excess of those described in A1.4.1.2 and A1.4.1.3may be reconditioned by grinding or machining provided thediameter is not reduced below the specified minimum.APPENDIX(Nonmandatory Information)X1. COMPOSITIONS FOR AXLE APPLICATIONSX1.1 For the guidance of
47、the purchaser, typical standardcompositions that cloud be used for axle applications are listedbelow, however the diameter of the axle at the time of heattreatment must be taken into account when selecting theforging composition.Grade Standard CompositionSpecification A 29/A 29MB 4130C 4140D 8630SUM
48、MARY OF CHANGESCommittee A01 has identified the location of selected changes to this standard since the last issue(A 729/A 729M 06) that may impact the use of this standard. (Approved April 1, 2009.)(1) Added AAR Manual of Standards and RecommendedPractices to Section 2.(2) Revised Table 2.A 729/A 7
49、29M 096ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five yea
