1、Designation: A878/A878M 05 (Reapproved 2011)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
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.1. Scope*1.1 This specification covers the highest quality of round and shaped modified chromiu
3、m vanadium alloy steel valve springwire, uniform in quality and temper, intended for the manufacture of valve springs and other springs requiring high-fatigueproperties when used at moderately elevated temperatures. It is similar to the grade VD (referenced in EN 10270-2) intended forhigh fatigue le
4、vels. This wire shall be either in the annealed and cold-drawn or oil-tempered condition as specified by purchaser.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, theinch-pound units are shown in brackets. The values stated in
5、each system are not exact equivalents; therefore, each systemmustshall be used independent of the other. Combining values from the two systems may result in non-conformance with thestandard.1.3 This international standard was developed in accordance with internationally recognized principles on stan
6、dardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanica
7、l Testing of Steel ProductsA700 Guide for Packaging, Marking, and Loading Methods for Steel Products for ShipmentA941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and FerroalloysA751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel ProductsE8/E8M Test Method
8、s for Tension Testing of Metallic MaterialsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE45 Test Methods for Determining the Inclusion Content of Steel2.2 Federal Standard:3Fed. Std. No. 123 Marking for Shipment (Civil Agencies)2.3 Military Stand
9、ard:3MIL-STD-163 Steel Mill Products, Preparation for Shipment and Storage2.4 AIAGEuropean Standard:4AIAG B-5EN10270-2 02.00 Primary Metals Identification Tag Application StandardSteel Wire for Mechanical Springs Part 2:Oil-Hardened and Tempered Spring Steel Wire of Unalloyed and Alloyed Steels3. Te
10、rminology3.1 Definitions:3.1.1 For definition of terms used in this specification, refer to Terminology A941.3.2 Definitions of Terms Specific to This Standard:1 This specification is under the jurisdiction ofASTM Committee A01 on Steel, Stainless Steel and RelatedAlloysand is the direct responsibil
11、ity of Subcommittee A01.03on Steel Rod and Wire.Current edition approved Nov. 1, 2011Sept. 1, 2017. Published November 2011September 2017. Originally approved in 1987. Last previous edition approved in 20052011as A878/A878M 05.A878/A878M 05 (2011). DOI: 10.1520/A0878_A0878M-05R11.10.1520/A0878_A0878
12、M-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Standardization Documents Order Desk, D
13、ODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-50984 Available from Automotive Industry Action Group (AIAG), 26200 Lahser Rd., Suite 200, Southfield, MI 48034.European Committee for Standardization,CEN-CENELEC Management Centre, Avenue Marnix 17, B-1000 Brussels, Belgium.This do
14、cument 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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions a
15、s appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*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. Unit
16、ed States13.2.1 equivalent round diameter, ndiameter of a round wire having equivalent cross sectional area to a given shaped wire.3.2.2 shape factor, n a value used to obtain cross sectional area for shaped wires when multiplied by measured width andmeasured thickness.4. Ordering Information4.1 Ord
17、ers for material under this specification shall include the following information for each ordered item:4.1.1 Quantity (mass),4.1.2 Name of material (modified chromium vanadium alloy steel valve spring quality wire),4.1.3 Dimensions (Table 1 and Section 89),4.1.4 Condition (Section 67),4.1.5 Packagi
18、ng (Section 1415),4.1.6 Heat analysis report, if requested (5.26.2),4.1.7 Certification or test report, or both, if specified (Section 1314), and4.1.8 ASTM designation and year of issue.NOTE 1Atypical ordering description is as follows: 20 000-kg oil-tempered modified chromium vanadium alloy steel v
19、alve spring quality wire, size6.00 mm in 150-kg coils to ASTM _ dated _ , or for inch-pound, 40 000-lb oil-tempered modified chromium vanadium alloy steel valve springquality wire, size 0.250 in. in 350-lb coils to ASTM _ dated _ .5. Materials and Manufacture5.1 The steel mayshall be made by any com
20、mercially accepted steel making process. The steel shall be continuously cast. a steelmaking process combined with secondary ladle refining that is capable of satisfying the inclusion content requirements of thisspecification.5.2 The steel shall be continuously cast into blooms and rolled into bille
21、ts.5.3 Billet conditioning shall precede wire rod manufacture. The resulting wire rods shall be of sufficient surface quality thatwhen combined with a surface removal operation performed prior to or during the wire manufacturing operation the resulting wireshall satisfy the surface condition and dec
22、arburization requirements of this specification.5.4 The finished wire shall be free from detrimental pipe and undue segregation.5.5 Alternate manufacturing processes may be used upon agreement between purchaser and supplier provided that the minimumrequirements of this standard are met.6. Chemical C
23、omposition6.1 The steel shall conform to the requirements for chemical composition specified in Table 2.6.2 Heat AnalysisEach heat of steel shall be analyzed by the manufacturer to determine the percentage of elements prescribedin Table 2. This analysis shall be made from a test specimen preferably
24、taken during the pouring of the heat. When requested, thisshall be reported to the purchaser and shall conform to the requirements of Table 2.6.3 Product AnalysisAn analysis may be made by the purchaser from finished wire representing each heat of steel. Theaverage of all the separate determinations
25、 made shall be within the limits specified in the analysis column. Individualdeterminations may vary to the extent shown in the product analysis tolerance column, except that the several determinations ofa single element in any one heat shall not vary both above and below the specified range.TABLE 1
26、 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,in.0.020 to 0.075, incl
27、 0.0008 0.0008Over 0.075 to 0.148, incl 0.001 0.001Over 0.148 to 0.375, incl 0.0015 0.0015A For purposes of determining conformance with this specification, all specifiedlimits are absolute as defined in Recommended Practice E29.A878/A878M 1726.4 For referee purposes, Test Methods, Practices, and Te
28、rminology A751 shall be used.7. Mechanical Properties6.1 Annealed and Cold DrawnWhen purchased in the annealed and cold-drawn condition, the wire shall have been given asufficient amount of cold working to meet the purchasers coiling requirements and shall be in a suitable condition to respondproper
29、ly to heat treatment. In special cases the hardness, if desired, shall be stated in the purchase order.7.1 Oil TemperedTension Test: When purchased in the oil-tempered condition, the tensile strength and % R.A. shall conformto the requirements prescribed in Table 3.7.1.1 Requirements for Annealed an
30、d Cold Drawn WiresTension test requirements, if any, shall be stated on the purchaseorder.7.1.2 Requirements for Oil-tempered WiresThe material as represented by tension test specimens shall conform to therequirements in Table 3. Variation in tensile strength within a coil shall not exceed 70 Mpa 10
31、.15 ksi.7.1.3 Number of TestsOne For oil-tempered wires, each coil in a lot shall be tested. When specified for annealed and colddrawn wires, one test specimen shall be taken for each five coils, or fraction thereof, in a lot. Each heat in a given lot shall be tested.7.1.4 Location of TestsTest For
32、oil-tempered wires, test specimens shall be taken from both ends of the coil. For annealed andcold drawn wires, test specimens shall be taken from either end of the coil.7.1.5 Test MethodThe tension test shall be made in accordance with Test Methods and Definitions A370. Any tensile testspecimen bre
33、aking in the tensile grips shall be discarded and a new specimen tested if the specified mechanical properties are notachieved. For shaped wires, cross sectional area shall be calculated either using the procedure in Test Methods E8/E8M for uniformbut nonsymmetrical cross-sections, or measuring widt
34、h and thickness and multiplying by a shape factor. Reduction of area forshaped wires shall be calculated by using this shape factor. Measure the maximum and minimum dimension on the necked downsection and multiply by the shape factor to estimate the cross sectional area for use in the standard reduc
35、tion of area calculation.7.1.5.1 Upon agreement between purchaser and supplier, the shape factor for the design provided by the wire mill shall bepermissible to be adopted for use. In other situations if the shape factor is not available from the wire mill, the shape factor shallbe calculated by mea
36、suring the cross sectional area in accordance with Test Methods E8/E8M and dividing by the width andthickness.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
37、mm 0.312 in. in diameter shall wrap without breakage on a mandreltwice the wire diameter. The wrap test is not applicable to wire over 8.00 mm 0.312 in. in diameter. For shaped wires, mandrelsize shall be selected based on the equivalent round wire diameter.7.2.2 Number of TestsOne test specimen sha
38、ll be taken for each five coils, or fraction thereof, in a lot. Each heat in a givenlot shall be tested.7.2.3 Location of TestsTest specimens It shall be taken permissible to take test specimens from either end of the coil.7.2.4 Test MethodThe wrap test shall be made in accordance with Test Methods
39、and Definitions A370.7.3 Special Surface InspectionWhen specified, the The entire length of every coil shall be inspected for surface imperfectionswith a magnetic or rotating and stationary probe eddy current defect analyzer,analyzer or both, or equivalent. The defect depth ofthis surface inspection
40、 shall be agreed upon between the manufacturer and the purchaser. All detected defects shall be equivalent.Imperfections deeper than 0.04 mm 0.0016 in shall be properly marked so the purchaser has the ability to identify and discardthat length of wire.wire; other depths may be agreed upon. Number of
41、 allowable marks per coil shall be agreed upon between themanufacturer and purchaser. This test is not applicable to wire diameters or equivalent round diameters below 2.5 mm 0.098 in.NOTE 2Special surface inspection of certain cross sectional shapes may not be technically feasible.8. Metallurgical
42、Requirements8.1 Surface Condition:TABLE 2 Chemical RequirementsAnalysis, % Product 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 1738.1.1 The surface of the
43、wire as received shall be free of imperfections such as pits, die marks, scratches, seams, and otherdefects tending to impair the fatigue value of the springs.8.1.2 Number of TestsOne test specimen shall be taken from each end of every coil.8.1.3 Test MethodThe surface shall be examined after etchin
44、g in a solution of equal parts of hydrochloric acid and water thathas been heated to approximately 80C for up to 2 min in order to remove the oxide scale layer from the wire surface. Test endsshall be examined using 10 magnification.8.2 Decarburization:8.2.1 Transverse sections of the wire properly
45、mounted, polished, and etched shall show no completely decarburized(carbon-free) areas when examined at a magnification of 100 diameters. Partial decarburization shall not exceed a depth of 0.025mm 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 i
46、n. For shapedwires, equivalent round wire diameter shall apply.8.2.2 To reveal the decarburization more accurately in untempered wire, the specimen shall be hardened and tempered beforemicroscopic examination. Prior to hardening, the specimen shall be filed flat on one side enough to reduce the diam
47、eter at least20 %. The subsequent mounted specimen shall show the flattened section, as well as the original wire edge. Any decarburizationon this flattened section shall necessitate a new specimen for examination.8.2.3 Number of TestsOne test specimen shall be taken for each five coils, or fraction
48、 thereof, in a lot.8.2.4 Location of TestsTest specimens may be taken It shall be permissible to take test specimens from either end of the coil.TABLE 3 Tensile RequirementsASI UnitsDiameter, mm MPa, min MPa, max Min %R.A.Reductionof AreaB0.5 2000 2170 0.5 2000 2170 . . .1.0 1930 2100 1.0 1930 2100
49、. . .1.5 1830 2000 1.5 1830 2000 . . .2.0 1760 1900 452.0 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, max Min % R.A.BDiameter, in. ksi, min ksi, maxMin %Reduction ofAreaB0.020 290 315 0.020 290 315 . . .0.040 280 305 0.040 280 305 . . .0.060 265 290 0.060 265 290 . . .0.080 255 275 450.080 255 275 . . .0.120 240 260 450.148 235 255 400.177 230 250 400.200 225 245 4
