1、Designation: A756 09 (Reapproved 2014)Standard Specification forStainless Anti-Friction Bearing Steel1This standard is issued under the fixed designation A756; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the requirements forchromium-carbon bearing quality stainless steel to be used inthe manufacture of ant
3、i-friction bearings.1.2 Supplementary Requirements of an optional nature areprovided and when desired shall be so stated in the order.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for
4、 information onlyand are not considered standard.2. Referenced Documents2.1 ASTM Standards:2A484/A484M Specification for General Requirements forStainless Steel Bars, Billets, and ForgingsA751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel ProductsE45 Test Methods for Deter
5、mining the Inclusion Content ofSteelE381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and ForgingsE1019 Test Methods for Determination of Carbon, Sulfur,Nitrogen, and Oxygen in Steel, Iron, Nickel, and CobaltAlloys by Various Combustion and Fusion TechniquesE1077 Test Methods for Estimati
6、ng the Depth of Decarbur-ization of Steel Specimens2.2 Other Standards:ISO 683 Part 17 Ball and Roller Bearing Steels3SAE J418a Grain Size Determination of Steel43. Ordering Information3.1 Orders for material under specification should includethe following information:3.1.1 Quantity,3.1.2 Grade iden
7、tification,3.1.3 Specification designation and year of issue,3.1.4 Dimensions, shape, and3.1.5 Supplementary Requirements, if desired.4. Process4.1 The steel shall be made by a process that is capable ofproviding a high-quality product meeting the requirements ofthis specification.5. Chemical Compos
8、ition5.1 Typical examples of chemical compositions are shownin Table 1. Other compositions may be specified.5.2 An analysis of each heat of steel shall be made by thesteel manufacturer in accordance with Test Methods, Practices,and Terminology A751. The chemical composition thus deter-mined shall co
9、nform to the requirements specified in Table 1for the ordered grade or to requirements agreed upon betweenthe manufacturer and the purchaser.5.3 Product analysis may be made by the purchaser inaccordance with Test Methods, Practices, and TerminologyA751. Permissible variations in product analysis sh
10、all be madein accordance with Specification A484/A484M.6. Dimensions, Mass, and Permissible Variations6.1 The size and shape of the material shall be agreed uponbetween manufacturer and purchaser.6.2 Dimensional tolerances for hot-rolled or hot-rolled andannealed bars, in straight lengths or coils,
11、and cold-finishedbars 0.500 in. (12.7 mm) and larger in diameter furnished underthis specification shall conform to the requirements specified inthe latest edition of Specification A484/A484M.6.3 Dimensional tolerances for cold-finished coils for balland roller material shall be as shown in Table 2.
12、6.4 Coil tolerances also apply to cold-finished straightlengths under 0.500 in. (12.7 mm) in diameter.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.28 on Bearing Steels.Current editi
13、on approved Oct. 1, 2014. Published October 2014. Originallyapproved in 1978. Last previous edition approved in 2009 as A756 09. DOI:10.1520/A0756-09R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSt
14、andards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org.4Available from SAE International (SAE), 400 Commonwealt
15、h Dr., Warrendale,PA 15096-0001, http:/www.sae.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Quality Tests7.1 The supplier shall be held responsible for the quality ofthe material furnished and shall make the necessary tests
16、toensure this quality. The supplier shall be required to report onthe results of the macroetch and microinclusion rating testsdetailed below. Quality tests shown in 7.2 through 7.4 arebased upon procedures established in Test Methods E45.7.2 SamplingSamples taken in accordance with the fol-lowing pa
17、ragraphs shall be obtained from 4 by 4-in. (102 by102-mm) rolled billets or forged sections. Tests may be madeon smaller or larger sections by agreement with the purchaser.A minimum 3 to 1 reduction of rolled billets or forged sectionsis required for strand cast products.7.2.1 For top poured product
18、s, a minimum of six samplesrepresenting the top and bottom of first, middle, and last usableingots shall be examined.7.2.2 For bottom poured products, a minimum of sixsamples shall be examined and they shall represent the top andbottom of three ingots. One ingot shall be taken at randomfrom the firs
19、t usable plate poured, one ingot, at random, fromthe usable plate poured nearest to the middle of the heat, andone ingot, at random, from the last usable plate poured. Whentwo usable plates constitute a heat, two of the sample ingotsshall be selected from the second usable plate poured. Where asingl
20、e usable plate constitutes a heat, any three random ingotsmay be selected. Other methods of sampling shall be as agreedupon between the manufacturer and the purchaser.7.2.3 For strand cast products, a minimum of six samplesrepresenting the first, middle, and last portion of the heat castshall be exa
21、mined. At least one sample shall be taken fromeach strand.7.3 MacroetchSpecimens representative of cross sectionsof billets shall be macroetched and rated in accordance withMethod E381 acid and water (1:1) at 160 to 180F (71 to82C). Such specimens shall not exceed S 2, R 2, and C2 ofMethod E381.7.4
22、Inclusion RatingThe specimens shall be38 by34 in.(9.5 by 19.1 mm) and shall be taken from an area halfwaybetween the center and outside of the billet. The polished faceshall be longitudinal to the direction of rolling. The scale usedfor rating the specimens shall be the Jernkontoret chartdescribed i
23、n Test Methods E45, Plate I-r. Fields with sizes ornumbers of all types of inclusions intermediate betweenconfigurations shown on the chart shall be classified as thelesser of the rating number. The worst field of each inclusiontype from each specimen shall be recorded as the rating for thespecimen.
24、 Two thirds of all specimens and at least one fromeach ingot tested, or from the first, middle, and last portion ofthe strands tested, as well as the average of all specimens, shallnot exceed the rating specified in Table 3.8. Response to Heat Treatment8.1 For chemical composition 440C, specimens wi
25、th sec-tions38 in. (9.5 mm) in thickness, cut from a bar, billet, orforging, shall be placed in a furnace that is at 1875 6 10F(1023.8 6 5.5C), allowed to heat to 1875 6 10F, held at heat25 min, and cooled in still air. Hardness of such specimensshall be not lower than 58 HRC.8.2 Samples heat treate
26、d as in 8.1 shall show a fracture grainsize of No. 6 or finer. (See SAE J418a.)9. Decarburization and Surface Imperfections9.1 Decarburization and surface imperfections shall notexceed the limits specified in Table 4 and Table 5. Decarbur-ization shall be measured using the microscopical methodsdesc
27、ribed in Test Methods E1077.TABLE 1 Chemical CompositionA,BNumberCName C Mn P (max) S (max) Si Cr Ni MoCu(max) O (max)DAl (max) Other. 440C 0.95 - 1.20 1.00 max 0.040 0.030 1.00max16.00 -18.000.75max0.40 -0.650.050 0.0020 0.050 . X30CrMoN15-1 0.25 - 0.35 1.00 max 0.030 0.025 1.00max14.00 -16.000.30-
28、0.500.85 -1.10. 0.0020 . N 0.300-0.500B50 X47Cr14 0.43 - 0.50 1.00 max 0.040 0.015 1.00max12.50 -14.50. . . 0.0020 . .B51 X65Cr14 0.60 - 0.70 1.00 max 0.040 0.015 1.00max12.50 -14.500.75max. . 0.0020 . .B52 X108CrMo17 0.95 - 1.20 1.00 max 0.040 0.015 1.00max16.00 -18.00. 0.40 -0.80. 0.0020 . .B53 X8
29、9CrMoV18-1 0.85 - 0.95 1.00 max 0.040 0.015 1.00max17.00 -19.00. 0.90 -1.30. 0.0020 . V 0.07 -0.12AElements not quoted shall not be intentionally added to the steel without the agreement of the purchaser.BIntentional additions of calcium or calcium alloys for deoxidation or inclusion shape control a
30、re not permitted unless specifically approved by the purchaser.CSteels B50 through B53 meet the requirements of ISO 683, Part 17, Second Edition, Table 3.DOxygen content applies to product analysis and shall be determined in accordance with Test Methods E1019.TABLE 2 Dimensional Tolerances for Cold-
31、Finished CoilsSize, in. (mm) Total Tolerance, in. (mm)Through 0.096 (2.44) 0.002 (0.05)Over 0.096 to 0.270 (2.44 to 6.86), incl 0.003 (0.08)Over 0.270 to 0.750 (6.86 to 19.1), incl 0.004 (0.10)TABLE 3 Inclusion RatingRating UnitsType Thin Series Heavy SeriesA 2.0 1.5B 2.5 1.5C 2.0 1.5D 2.0 1.0A756 0
32、9 (2014)210. Microstructure and Hardness10.1 The material shall be free of excessive carbide segre-gation.10.2 When annealing is specified in the order, the steel shallhave a predominantly spheroidized microstructure and a hard-ness as specified in Table 6.10.3 Small sizes where Rockwell B scale har
33、dness readingsare impractical shall show a maximum tensile strength of115 000 psi (792 mPa).11. Inspection11.1 The manufacturer shall afford the purchasers inspectorall reasonable facilities necessary to satisfy him that thematerial is being produced and furnished in accordance withthis specificatio
34、n. Mill inspection by the purchaser shall notinterfere unnecessarily with the manufacturers operations. Alltests and inspections shall be made at the place of manufacture,unless otherwise agreed to.12. Certification and Reports12.1 Upon request of the purchaser in the contract or order,a manufacture
35、rs certification that the material was manufac-tured and tested in accordance with this specification, togetherwith a report of the test results, shall be furnished at the timeof the shipment.SUPPLEMENTARY REQUIREMENTSOne or more of the Supplementary Requirements described below apply when included
36、in thepurchasers order or contract. When so included, a Supplementary Requirement shall have the sameforce as if it were in the body of the specification. Supplementary Requirements details not fullydescribed shall be agreed upon between the purchaser and the supplier, but shall not negate any of th
37、erequirements in the body of the specification.S1. Residual ElementsS1.1 The purchaser may specify that the analysis oftitanium, aluminum, and/or oxygen (Test Methods E1019)beprovided by agreement with the steel manufacturer. Thenumber and location of samples shall be by agreement betweenthe purchas
38、er and manufacturer.S2. Calcium AdditionsS2.1 Intentional additions of calcium or calcium alloys fordeoxidation or inclusion shape control are not permitted unlessspecifically approved by the purchaser. The use oflime orfluorspar, or both, in the steelmaking slag is acceptable.TABLE 4 Decarburizatio
39、n and Surface Imperfections for Coils and Bars for Balls and RollersSize, in. (mm)Decarburization or Surface Imperfections per Side, max, in. (mm)Hot-Rolled or Hot-Rolled AnnealedCold-FinishedAnnealedThrough 0.250 (6.35) 0.005 (0.13) 0.003 (0.08)Over 0.250 (6.35) to 0.500 (12.7), incl 0.006 (0.15) 0
40、.004 (0.10)Over 0.500 (12.7) to 0.750 (19.1), incl 0.008 (0.20) 0.006 (0.15)Over 0.750 (19.1) to 1.000 (25.4), incl 0.010 (0.25) 0.008 (0.20)TABLE 5 Decarburization and Surface Imperfections for Bars and TubesSize, in. (mm)Decarburization or Surface Imperfections per Side, max, in. (mm)Hot-Rolled Ba
41、rsHot-Rolled Annealed Cold-Finished AnnealedBars Tubes Bars TubesThrough 1.000 (25.4) 0.012 (0.31) 0.015 (0.38) 0.012 (0.31) 0.012 (0.31) 0.010 (0.21)Over 1.000 (25.4) to 2.000 (50.8), incl 0.017 (0.43) 0.022 (0.56) 0.020 (0.51) 0.015 (0.38) 0.014 (0.36)Over 2.000 (50.8) to 3.000 (76.2), incl 0.025
42、(0.64) 0.030 (0.76) 0.030 (0.76) 0.025 (0.64) 0.019 (0.48)Over 3.000 (76.2) to 4.000 (101.6), incl 0.035 (0.89) 0.045 (1.14) 0.035 (0.89) 0.024 (0.61)Over 4.000 (101.6) to 5.000 (127.0), incl 0.055 (1.40) 0.065 (1.65) 0.040 (1.02) 0.028 (0.71)TABLE 6 Maximum Hardness for Annealed MaterialMaximum Har
43、dnessProduct Condition Brinell RockwellCoils hot-rolled-annealed . . . 25 HRCBars and tubes hot-rolled-annealed 255 HB . . .Coils, bars, and tubes cold-drawn-annealed 255 HB 100 HRBCoils, bars, and tubes annealed-cold-drawn as agreed upon between the purchaser and the manufacturerA756 09 (2014)3S3.
44、Magnetic Particle MethodS3.1 The purchaser may specify that the magnetic particlemethod described be used in addition to the microinclusionrating system described in 7.4. The magnetic particle methodmeasures bearing steel cleanliness by evaluating the totallength of macroinclusions for a stated area
45、 or per unit area.Results are commonly expressed in millimetres per squaremetre.S3.2 SamplingSee 7.2.S3.3 Test specimens shall be straight cylinder quarter sec-tion samples prepared and examined in accordance with themagnetic particle method of Test Methods E45.S3.4 For purposes of calculation, an i
46、nclusion length shallbe taken as the mean length of the length bracket into which itfalls; that is, an inclusion in the116 to18-in. bracket shall betaken as being332 in. in length. The sum of all lengths for eachspecimen shall be determined and expressed as total length perarea inspected. The averag
47、e total length per area inspected ofall six specimens shall not exceed 200 mm /m2(or equivalent).S4. Sample Reduction RatioS4.1 For the sampling described in 7.2, the purchaser mayspecify that he reduction ratio from as-cast section to testsection be provided.ASTM International takes no position res
48、pecting 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
49、standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee o
