1、Designation: D 4975 04Standard Test Methods forSingle-Filament Tire Bead Wire Made from Steel1This standard is issued under the fixed designation D 4975; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover testing of single-filament steelwires that are components of tire beads used in the manufactureof pneumatic t
3、ires. By agreement, these test methods may beapplied to similar filaments used for reinforcing other rubberproducts.1.2 These test methods describe test procedures only and donot establish specifications and tolerances.1.3 This standard is written in SI units. No other units ofmeasurement are includ
4、ed in this standard.1.4 These test methods cover the determination of themechanical properties listed below:1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
5、and health practices and determine the applica-bility of regulatory limitations prior to use.Property SectionBreaking Force (Strength) 7-13Yield Strength 7-13Elongation 7-13Torsion Resistance 14-20Diameter (Gage) 21-272. Referenced Documents2.1 ASTM Standards:2A 370 Test Methods and Definitions for
6、Mechanical Testingof Steel ProductsD 76 Specification for Tensile Testing Machines for TextilesD 123 Terminology Relating to TextilesD 2969 Test Method for Steel Tire CordsD 4848 Terminology of Force, Delamination, and RelatedProperties of TextilesD 6477 Terminology Relating to Tire Cord, Bead Wire,
7、Hose Reinforcing Wire and FabricsE 6 Terminology Relating to Methods of Mechanical Test-ingE 558 Test Method for Torsion Testing of Wire3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to tire cord, bead wire,hose wire, and tire cord fabrics, refer to Terminology D 6477.3.1.1.1
8、The following terms are relevant to this standard:percent elongation, tire bead, tire bead wire, torsion resistance,in tire bead wire, yield strength.3.1.2 For definitions of terms related to force and deforma-tion in textiles, refer to Terminology D 48483.1.2.1 The following terms are relevant to t
9、his standard:breaking force.3.1.3 For definitions of other textile terms, refer to Termi-nology D 123.4. Summary of Test Methods4.1 A summary of the procedures prescribed for the deter-mination of specific properties of tire bead wire is stated in theappropriate sections of the specific test methods
10、 that follow.5. Significance and Use5.1 The procedures for the determination of properties ofsingle-filament bead wire made from steel are consideredsatisfactory for acceptance testing of commercial shipments ofthis product because the procedures are the best available andhave been used extensively
11、in the trade.5.1.1 In case of a dispute arising from differences inreported test results when using these test methods for accep-tance testing of commercial shipments, the purchaser andsupplier should conduct comparative test to determine if thereis a statistical bias between their laboratories. Com
12、petentstatistical assistance is recommended for the investigation ofbias. As a minimum, the two parties should take a group of testspecimens which are as homogeneous as possible and whichare from a lot of material of the type in question. The testspecimens then should be randomly assigned in equal n
13、umberto each laboratory for testing. The average results from the twolaboratories should be compared using Students t-test forunpaired data and an acceptable probability level chosen by thetwo parties before testing is begun. If a bias is found, either its1These test methods are under the jurisdicti
14、on of ASTM Committee D13 onTextiles and are the direct responsibility of Subcommittee D13.19 on Tire Cord andFabrics.Current edition approved Oct. 1, 2004. Published October 2004. Originallypublished as D 4975 89. Last previous edition D 4975 02a.2For referenced ASTM standards, visit the ASTM websit
15、e, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States
16、.cause must be determined and corrected or the purchaser andthe supplier must agree to interpret future test results withconsideration to the known bias.6. Sampling6.1 Lot SampleAs a lot sample for acceptance testing,take at random the number of reels, coils, spools, or othershipping units of wire d
17、irected in an applicable materialspecification or other agreement between the purchaser and thesupplier. Consider reels, coils, spools, or other shipping units ofwire to be the primary sampling units.NOTE 1A realistic specification or other agreement between thepurchaser and the supplier requires ta
18、king into account the variabilitybetween and within primary sampling units so as to provide a samplingplan which at the specified level of the property of interest has ameaningful producers risk, consumers risk, acceptable quality level, anddesired limiting quality level.6.2 Laboratory SampleUse the
19、 primary sampling units inthe lot sample as a laboratory sample.6.3 Test SpecimensFor each test procedure, take thenumber of lengths of tire bead wire of the specified lengthsfrom each laboratory sample as directed in the test procedure.BREAKING FORCE, YIELD STRENGTH, ANDELONGATION7. Summary of Test
20、 Method7.1 The two ends of a specimen are clamped in a tensiletesting machine; an increasing force is applied until thespecimen breaks. The change in force is measured versus theincrease in separation of the specimen clamps to form aforce-extension curve. Breaking force is read directly from thecurv
21、e and is expressed in newtons. Percent elongation at breakis the extension at break divided by the original specimenlength, 3 100. The yield strength, the intersection of theforce-extension curve with a line at 0.2 % elongation offset, isread from the force-extension curve and is expressed innewtons
22、.8. Significance and Use8.1 The load-bearing ability of a reinforced rubber productsuch as a tire bead is related to the strength of the single-filament wire used as the reinforcing material. The breakingforce and yield strength of tire bead wire is used in engineeringcalculations when designing thi
23、s type of reinforced product.8.2 Elongation of tire bead wire is taken into considerationin the design and engineering of tire beads because of its effecton uniformity and dimensional stability during service.9. Apparatus9.1 Tensile Testing Machine, CRE (Constant-Rate-of-Extension) tensile testing m
24、achine of such capacity that themaximum force required to fracture the wire shall not exceed90 % nor be of less than 10 % of the selected force measure-ment range. The specifications and methods of calibration andverification for tensile testing machines shall conform toSpecification D 76.9.2 In som
25、e laboratories, the output of CRE type of tensiletesting machine is connected with electronic recording andcomputing equipment which may be programmed to calculateand print the results for each of these desired properties.Because of the variety of electronic equipment available andthe various possib
26、ilities for recording test data, use of this typeof equipment is not covered in this test method.9.3 Grips, of such design that failure of the specimen doesnot occur at the gripping point, and slippage of the specimenwithin the jaws (grips) is prevented.10. Procedure10.1 Thermally age the specimen b
27、y placing it in an ovenfor 60 6 1 min, at 150 6 3C. Allow specimens to cool toroom temperature before testing.10.2 Select the proper force scale range on the tensiletesting machine based on the estimated breaking force of thespecimen being tested.10.3 Adjust the distance between the grips of the tes
28、tingmachine, nip to nip, to a gage length of 250 mm.10.4 Secure the specimen in the top clamp, exterting enoughpressure to prevent the specimen from slipping when loaded.Place the other end of the specimen between the jaws of thebottom clamp.10.5 Apply a pretension of 1 % of full scale to keep thesp
29、ecimen taut.10.6 After setting the cross head speed at 25 mm/min andrecorder chart speed at 250 mm/min, start the testing machineand record the force-extension curve generated.10.6.1 If the specimen fractures within 5 mm of the grippingpoint, discard the result and test another specimen. If such jaw
30、breaks continue to occur, insert a jaw liner such as an abrasivecloth between the gripping surface and the specimen in amanner so that the liner extends beyond the grip edge where itcomes in contact with the specimen.10.7 Conduct this test procedure on two specimens fromeach laboratory sampling unit
31、.10.8 Elongation, the increase in gage length of a tensilespecimen, is usually expressed as a percentage of the originalgage length and can be determined from the force-extensioncurve.10.8.1 When a greater degree of accuracy is required in thedetermination of elongation, an extensometer can be attac
32、hedto the specimen.10.9 Yield strength is the stress at which a material exhibitsa specified limiting deviation from the proportionality of stressto strain. Determine the yield strength by the 0.2 % offsetelongation method.10.9.1 On the force-extension curve (Fig. 1) that has beengenerated (see 10.6
33、) mark off Om equal to the specified valueof the offset (0.2 % elongation); draw mn parallel to OA andlocate r. This intersection of mn with the force-extension curvecorresponds to force R which is the yield strength. Should theforce-extension curve exhibit an initial nonlinear portion,extrapolate f
34、rom the straight line portion to the base line. Theintersection is point O used in this section.11. Calculation11.1 Calculate the average breaking force of the laboratorysample to the nearest 5 N.D497504211.2 Calculate the elongation to break from the force-extension curve to the nearest 0.1 %. Shou
35、ld the force-extension curve exhibit an initial nonlinear portion, extrapolatefrom the straight line portion of the curve to the base line. Thisintersection is the point of origin for the elongation determi-nation. The extension from this point to the force at the pointof break is the total elongati
36、on.11.3 Calculate the average yield strength of each laboratorysample as directed in 10.9.1 to the nearest 5 N.12. Report12.1 State that the tests were performed as directed in TestMethods D 4975, describe the material or product tested, andreport the following:12.1.1 The test results of each specim
37、en and the laboratorysample average. Calculate and report any other data agreed tobetween the purchaser and the supplier,12.1.2 Date of test,12.1.3 Type of tensile test machine and rate of extension,and12.1.4 Any deviation from the standard test procedure.13. Precision and Bias13.1 Interlaboratory T
38、est DataAn interlaboratory test wasrun in 1990 in which randomly drawn samples of fourmaterials were tested in 13 laboratories. Each laboratory usedtwo operators, each of whom tested two specimens of eachmaterial on two separate days.NOTE 2The bead wire products used in the interlaboratory evaluatio
39、nwere of the following diameter and strength levels:TABLEMaterial Diameter Strength1 0.965 mm regular2 0.965 mm high3 1.295 mm regular4 1.295 mm high13.2 PrecisionFor the property of interest, two averagesof observed values should be considered significantly differentat the 95 % probability level if
40、 the difference equals or exceedsthe critical differences given in Table 1.NOTE 3The tabulated values of the critical differences should beconsidered to be a general statement, particularly with respect to betweenlaboratory precision. Before a meaningful statement can be made con-cerning any two spe
41、cific laboratories, the amount of statistical bias, if any,between them must be established, with each comparison being based onrecent data obtained on specimens taken from a lot of material of the typebeing evaluated so as to be as nearly homogeneous as possible and thenassigned randomly in equal n
42、umbers to each of the laboratories.13.3 BiasThe procedures in this test method for measur-ing breaking force, elongation, and yield strength have noknown bias because the value of these properties can bedefined only in terms of a test method.TORSION RESISTANCE14. Summary of Test Method14.1 A single-
43、filament of wire is tested in torsion by eitherholding one end of the wire fixed while rotating the other or byrotating both ends in opposite directions at the same time untilfracture occurs.15. Significance and Use15.1 Complex stress and strain conditions, sensitive tovariations in materials, occur
44、 in a wire specimen during torsiontesting. The torsion test is a useful tool in assessing wireductility under torsional loading. Defective wire lowers torsionresistance.16. Apparatus16.1 Torsion Test Machine, an automated drive apparatusthat allows a single-filament wire under light tension to betes
45、ted in torsion. A counter is provided that registers thenumber of wire rotations to wire fracture.17. Procedure17.1 Thermally age the specimen by placing it in a suitableoven for 60 6 1 min. at 150 6 3C. Allow specimens to coolto room temperature before testing.17.2 Cut the test specimen to the appr
46、opriate length so thata gage length of 200 mm between chuck or jaw edges isobtained.17.3 Certain test equipment requires that a 90 bend be putin each end of the test specimen; if that is required, measureapproximately 25 mm from each end and bend the wire 90with both bends in the same direction.17.4
47、 Place the specimen in the clamping fixtures and tightenthe jaws while keeping the wire in a straight alignment. Apretension 25 6 5 N shall be applied to the specimen in thelongitudinal direction to aid in keeping the wire straight duringtesting.17.5 Set the rotation counter to zero.17.6 Start the e
48、quipment and run until the specimen frac-tures. For wire sizes below 1.40 mm, use a rotation speed of 606 15 r/min. For wire sizes greater than 1.40 mm, use a rotationspeed of 45 6 15 r/min.FIG. 1 Force-Extension Curve for Determination of YieldStrength by the Offset MethodD4975043NOTE 4Speeds in ex
49、cess of these cause excessive specimen heatingand can cause inaccurate results.17.6.1 If the specimen fails within twice its diameter fromthe jaw edge it is considered to be a jaw break, and the resultshould be discarded and another specimen tested.17.7 Conduct this test procedure on two specimens fromeach laboratory sampling unit.TABLE 1 Critical Differences for Conditions NotedName of PropertyNumber ofObservationsSingle Operator PrecisionWithin-LaboratoryPrecisionBetween-Laboratory PrecisionSingle-Material ComparisonsBreaking force, N 1 17 17 2721212 25499 386616
