1、Designation: A878/A878M 17Standard Specification forSteel Wire, Modified Chromium Vanadium Valve SpringQuality1This standard is issued under the fixed designation A878/A878M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year
2、 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 the highest quality of roundand shaped modified chromium vanadium alloy steel valvespri
3、ng wire, uniform in quality and temper, intended for themanufacture of valve springs and other springs requiringhigh-fatigue properties when used at moderately elevatedtemperatures. It is similar to the grade VD (referenced in EN10270-2) intended for high fatigue levels. This wire shall beeither in
4、the annealed and cold-drawn or oil-tempered condi-tion as specified by purchaser.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. Within the text, theinch-pound units are shown in brackets. The values stated ineach system are not exact equivalent
5、s; therefore, each systemshall be used independent of the other. Combining values fromthe two systems may result in non-conformance with thestandard.1.3 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision
6、 on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA700 Guide f
7、or Packaging, Marking, and Loading Methodsfor Steel Products for ShipmentA941 Terminology Relating to Steel, Stainless Steel, RelatedAlloys, and FerroalloysA751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel ProductsE8/E8M Test Methods for Tension Testing of Metallic Ma-ter
8、ialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE45 Test Methods for Determining the Inclusion Content ofSteel2.2 Federal Standard:3Fed. Std. No. 123 Marking for Shipment (Civil Agencies)2.3 Military Standard:3MIL-STD-163 Steel Mill Products, Pre
9、paration for Ship-ment and Storage2.4 European Standard:4EN10270-2 Steel Wire for Mechanical Springs Part 2: Oil-Hardened and Tempered Spring Steel Wire of Unalloyedand Alloyed Steels3. Terminology3.1 Definitions:3.1.1 For definition of terms used in this specification, referto Terminology A941.3.2
10、Definitions of Terms Specific to This Standard:3.2.1 equivalent round diameter, ndiameter of a roundwire having equivalent cross sectional area to a given shapedwire.3.2.2 shape factor, n a value used to obtain cross sectionalarea for shaped wires when multiplied by measured width andmeasured thickn
11、ess.4. Ordering Information4.1 Orders for material under this specification shall includethe following information for each ordered item:4.1.1 Quantity (mass),4.1.2 Name of material (modified chromium vanadiumalloy steel valve spring quality wire),4.1.3 Dimensions (Table 1 and Section 9),1This speci
12、fication is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloysand is the direct responsibility of SubcommitteeA01.03 on Steel Rod and Wire.Current edition approved Sept. 1, 2017. Published September 2017. Originallyapproved in 1987. Last previous edition approve
13、d in 2011 as A878/A878M 05 (2011). DOI: 10.1520/A0878_A0878M-17.2For 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 Document Summary page onthe ASTM websi
14、te.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-50984Available from European Committee for Standardization, CEN-CENELECManagement Centre, Avenue Marnix 17, B-1000 Brussels, Belgium.*A Summary of Changes section appears at t
15、he end of this standardThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Tech
16、nical Barriers to Trade (TBT) Committee.14.1.4 Condition (Section 7),4.1.5 Packaging (Section 15),4.1.6 Heat analysis report, if requested (6.2),4.1.7 Certification or test report, or both, if specified (Sec-tion 14), and4.1.8 ASTM designation and year of issue.NOTE 1A typical ordering description i
17、s as follows: 20 000-kgoil-tempered modified chromium vanadium alloy steel valve springquality wire, size 6.00 mm in 150-kg coils toASTM _ dated _ , or forinch-pound, 40 000-lb oil-tempered modified chromium vanadium alloysteel valve spring quality wire, size 0.250 in. in 350-lb coils toASTM _dated
18、_ .5. Materials and Manufacture5.1 The steel shall be made by a steel making processcombined with secondary ladle refining that is capable ofsatisfying the inclusion content requirements of this specifica-tion.5.2 The steel shall be continuously cast into blooms androlled into billets.5.3 Billet con
19、ditioning shall precede wire rod manufacture.The resulting wire rods shall be of sufficient surface qualitythat when combined with a surface removal operation per-formed prior to or during the wire manufacturing operation theresulting wire shall satisfy the surface condition and decarbur-ization req
20、uirements of this specification.5.4 The finished wire shall be free from detrimental pipeand undue segregation.5.5 Alternate manufacturing processes may be used uponagreement between purchaser and supplier provided that theminimum requirements of this standard are met.6. Chemical Composition6.1 The
21、steel shall conform to the requirements for chemicalcomposition specified in Table 2.6.2 Heat AnalysisEach heat of steel shall be analyzed bythe manufacturer to determine the percentage of elementsprescribed in Table 2. This analysis shall be made from a testspecimen preferably taken during the pour
22、ing of the heat.When requested, this shall be reported to the purchaser andshall conform to the requirements of Table 2.6.3 Product AnalysisAn analysis may be made by thepurchaser from finished wire representing each heat of steel.The average of all the separate determinations made shall bewithin th
23、e limits specified in the analysis column. Individualdeterminations may vary to the extent shown in the productanalysis tolerance column, except that the several determina-tions of a single element in any one heat shall not vary bothabove and below the specified range.6.4 For referee purposes, Test
24、Methods, Practices, andTerminology A751 shall be used.7. Mechanical Properties7.1 Tension Test:7.1.1 Requirements for Annealed and Cold Drawn WiresTension test requirements, if any, shall be stated on thepurchase order.7.1.2 Requirements for Oil-tempered WiresThe materialas represented by tension te
25、st specimens shall conform to therequirements in Table 3. Variation in tensile strength within acoil shall not exceed 70 Mpa 10.15 ksi.7.1.3 Number of TestsFor oil-tempered wires, each coil ina lot shall be tested. When specified for annealed and colddrawn wires, one test specimen shall be taken for
26、 each fivecoils, or fraction thereof, in a lot. Each heat in a given lot shallbe tested.7.1.4 Location of TestsFor oil-tempered wires, test speci-mens shall be taken from both ends of the coil. For annealedand cold drawn wires, test specimens shall be taken from eitherend of the coil.7.1.5 Test Meth
27、odThe tension test shall be made inaccordance with Test Methods and Definitions A370. Anytensile test specimen breaking in the tensile grips shall bediscarded and a new specimen tested if the specified mechani-cal properties are not achieved. For shaped wires, crosssectional area shall be calculated
28、 either using the procedure inTest Methods E8/E8M for uniform but nonsymmetrical cross-sections, or measuring width and thickness and multiplying bya shape factor. Reduction of area for shaped wires shall becalculated by using this shape factor. Measure the maximumand minimum dimension on the necked
29、 down section andmultiply by the shape factor to estimate the cross sectional areafor use in the standard reduction of area calculation.7.1.5.1 Upon agreement between purchaser and supplier,the shape factor for the design provided by the wire mill shallbe permissible to be adopted for use. In other
30、situations if theTABLE 1 Permissible Variations in Wire DiameterASI UnitsDiameter, mmPermissibleVariations,mmPermissibleOut-of Round,mm0.5 to 2.0, incl 0.02 0.02Over 2.0 to 4.0, incl 0.03 0.03Over 4.0 to 9.5, incl 0.04 0.04Inch-Pound UnitsDiameter, in.PermissibleVariations,in.PermissibleOut-of Round
31、,in.0.020 to 0.075, incl 0.0008 0.0008Over 0.075 to 0.148, incl 0.001 0.001Over 0.148 to 0.375, incl 0.0015 0.0015AFor purposes of determining conformance with this specification, all specifiedlimits are absolute as defined in Recommended Practice E29.TABLE 2 Chemical RequirementsAnalysis, % Product
32、 AnalysisTolerance, %Carbon 0.600.75 0.02Manganese 0.500.90 0.03Phosphorus 0.025 max +0.005Sulfur 0.025 max +0.005Silicon 0.150.30 0.02Chromium 0.350.60 0.05Vanadium 0.100.25 0.01A878/A878M 172shape factor is not available from the wire mill, the shapefactor shall be calculated by measuring the cros
33、s sectional areain accordance with Test Methods E8/E8M and dividing by thewidth and thickness.7.2 Wrap Test:7.2.1 Oil-tempered or cold-drawn wire 4.00 mm 0.162 in.and smaller in diameter shall wind on itself as an arbor withoutbreakage. Larger diameter wire up to and including 8.00 mm0.312 in. in di
34、ameter shall wrap without breakage on amandrel twice the wire diameter. The wrap test is not appli-cable to wire over 8.00 mm 0.312 in. in diameter. For shapedwires, mandrel size shall be selected based on the equivalentround wire diameter.7.2.2 Number of TestsOne test specimen shall be taken foreac
35、h five coils, or fraction thereof, in a lot. Each heat in a givenlot shall be tested.7.2.3 Location of TestsIt shall be permissible to take testspecimens from either end of the coil.7.2.4 Test MethodThe wrap test shall be made in accor-dance with Test Methods and Definitions A370.7.3 Special Surface
36、 InspectionThe entire length of everycoil shall be inspected for surface imperfections with a rotatingand stationary probe eddy current defect analyzer or equiva-lent. Imperfections deeper than 0.04 mm 0.0016 in shall beproperly marked so the purchaser has the ability to identify anddiscard that len
37、gth of wire; other depths may be agreed upon.Number of allowable marks per coil shall be agreed uponbetween the manufacturer and purchaser. This test is notapplicable to wire diameters or equivalent round diametersbelow 2.5 mm 0.098 in.NOTE 2Special surface inspection of certain cross sectional shap
38、esmay not be technically feasible.8. Metallurgical Requirements8.1 Surface Condition:8.1.1 The surface of the wire as received shall be free ofimperfections such as pits, die marks, scratches, seams, andother defects tending to impair the fatigue value of the springs.8.1.2 Number of TestsOne test sp
39、ecimen shall be takenfrom each end of every coil.8.1.3 Test MethodThe surface shall be examined afteretching in a solution of equal parts of hydrochloric acid andwater that has been heated to approximately 80C for up to 2min in order to remove the oxide scale layer from the wiresurface. Test ends sh
40、all be examined using 10 magnification.8.2 Decarburization:8.2.1 Transverse sections of the wire properly mounted,polished, and etched shall show no completely decarburized(carbon-free) areas when examined at a magnification of 100diameters. Partial decarburization shall not exceed a depth of0.025 m
41、m 0.001 in. on wire 5.00 mm 0.192 in. and smaller,or 0.038 mm 0.0015 in. on larger than 5.00 mm 0.192 in.For shaped wires, equivalent round wire diameter shall apply.8.2.2 To reveal the decarburization more accurately inuntempered wire, the specimen shall be hardened and temperedbefore microscopic e
42、xamination. Prior to hardening, the speci-men shall be filed flat on one side enough to reduce thediameter at least 20 %. The subsequent mounted specimenshall show the flattened section, as well as the original wireedge. Any decarburization on this flattened section shallnecessitate a new specimen f
43、or examination.8.2.3 Number of TestsOne test specimen shall be taken foreach five coils, or fraction thereof, in a lot.8.2.4 Location of TestsIt shall be permissible to take testspecimens from either end of the coil.8.3 Inclusion Content:8.3.1 The inclusion content of the wire or wire rod in thewors
44、t case shall not exceed the limits shown in Table 4 asdescribed in Test Methods E45, Plate I-A, Method D, exceptthat alternate methodologies are acceptable upon agreementbetween purchaser and supplier provided minimum require-ments are not lower than those of Test Methods E45, MethodD.8.3.1.1 If any
45、 coil exceeds the limits listed in Table 4, allcoils in the lot will be inspected. Each coil that fails to meet therequirements will be rejected.8.3.2 Number of TestsOne test specimen shall be taken foreach 10 coils, or fraction thereof, in the lot.8.3.3 Location of TestsIt shall be permissible to t
46、ake testspecimens from either end of the coil.8.3.4 Test MethodA longitudinal section approximately12.7 mm 0.5 in. long shall be ground to the centerline andTABLE 3 Tensile RequirementsASI UnitsDiameter, mm MPa, min MPa, max Min %Reduction ofAreaB0.5 2000 2170 . . .1.0 1930 2100 . . .1.5 1830 2000 .
47、 . .2.0 1760 1900 . . .3.0 1660 1800 453.75 1620 1760 404.5 1590 1730 405.0 1550 1690 405.7 1520 1660 406.3 1480 1620 407.9 1450 1590 409.5 1410 1550 40Inch-Pound UnitsDiameter, in. ksi, min ksi, maxMin %Reduction ofAreaB0.020 290 315 . . .0.040 280 305 . . .0.060 265 290 . . .0.080 255 275 . . .0.1
48、20 240 260 450.148 235 255 400.177 230 250 400.200 225 245 400.225 220 240 400.250 215 235 400.312 210 230 400.375 205 225 40ATensile strength valves for intermediate diameters shall be interpolated.BThe reduction of area test is not applicable to wire diameters under 2.34 mm0.092 in. For intermedia
49、te diameters, the reduction of area requirement shall bethat of the next larger wire diameter.“. . .” Indicates that there is no requirement.A878/A878M 173properly mounted and polished. Examination shall be made inaccordance with Test Methods E45.8.3.5 Upon agreement by the purchaser and supplier, theinclusion requirements may be waived.9. Dimensions and Permissible Variations9.1 The permissible variations in the diameter of the wireshall be as specified in Table 1.9.2 Number of TestsOne test specimen shall be t
