ASTM D4975-2014 Standard Test Methods for Single-Filament Tire Bead Wire Made from Steel《单股轮胎边钢丝的标准试验方法》.pdf

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1、Designation: D4975 14Standard Test Methods forSingle-Filament Tire Bead Wire Made from Steel1This standard is issued under the fixed designation D4975; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu

2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 tire

3、s. 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 The values stated in SI units are to be regarded asstandard. No other units of m

4、easurement are included in thisstandard.1.4 These test methods cover the determination of themechanical properties listed below:Property SectionBreaking Force (Strength) 713Yield Strength 713Elongation 713Torsion Resistance 1420Diameter (Gage) 21271.5 This standard does not purport to address all of

5、 thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76 Specification for Te

6、nsile Testing Machines for TextilesD123 Terminology Relating to TextilesD4848 Terminology Related to Force, Deformation andRelated Properties of TextilesD6477 Terminology Relating to Tire Cord, Bead Wire, HoseReinforcing Wire, and Fabrics3. Terminology3.1 Definitions:3.1.1 For definitions of terms r

7、elating to tire cord, bead wire,hose wire, and tire cord fabrics, refer to Terminology D6477.3.1.1.1 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 a

8、nd deforma-tion in textiles, refer to Terminology D48483.1.2.1 The following terms are relevant to this standard:breaking force.3.1.3 For definitions of other textile terms, refer to Termi-nology D123.4. Summary of Test Methods4.1 A summary of the procedures prescribed for the deter-mination of spec

9、ific properties of tire bead wire is stated in theappropriate sections of the specific test methods 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 sh

10、ipments ofthis product because the procedures are the best available andhave been used extensively 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

11、conduct comparative test to determine if thereis a statistical bias between their laboratories. Competentstatistical 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

12、of material of the type in question. The testspecimens then should be randomly assigned in equal numberto 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 b

13、efore testing is begun. If a bias is found, either itscause must be determined and corrected or the purchaser andthe supplier must agree to interpret future test results withconsideration to the known bias.1These test methods are under the jurisdiction of ASTM Committee D13 onTextiles and are the di

14、rect responsibility of Subcommittee D13.19 on IndustrialFibers and Metallic Reinforcements.Current edition approved May 15, 2014. Published June 2014. Originallyapproved in 1989. Last previous edition approved in 2011 as D497504(2011). DOI:10.1520/D4975-14.2For referenced ASTM standards, visit the A

15、STM 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 website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unit

16、ed States16. Sampling6.1 Lot SampleAs a lot sample for acceptance testing, takeat random the number of reels, coils, spools, or other shippingunits of wire directed in an applicable material specification orother agreement between the purchaser and the supplier.Consider reels, coils, spools, or othe

17、r shipping units of wire tobe the primary sampling units.NOTE 1A realistic specification or other agreement between thepurchaser and the supplier requires taking into account the variabilitybetween and within primary sampling units so as to provide a samplingplan which at the specified level of the

18、property of interest has ameaningful producers risk, consumers risk, acceptable quality level, anddesired limiting quality level.6.2 Laboratory SampleUse the primary sampling units inthe lot sample as a laboratory sample.6.3 Test SpecimensFor each test procedure, take the num-ber of lengths of tire

19、bead wire of the specified lengths fromeach laboratory sample as directed in the test procedure.BREAKING FORCE, YIELD STRENGTH, ANDELONGATION7. Summary of Test Method7.1 The two ends of a specimen are clamped in a tensiletesting machine; an increasing force is applied until thespecimen breaks. The c

20、hange in force is measured versus theincrease in separation of the specimen clamps to form aforce-extension curve. Breaking force is read directly from thecurve and is expressed in newtons. Percent elongation at breakis the extension at break divided by the original specimenlength, 100. The yield st

21、rength, the intersection of the force-extension curve with a line at 0.2 % elongation offset, is readfrom the force-extension curve and is expressed in newtons.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 sing

22、le-filament wire used as the reinforcing material. The breakingforce and yield strength of tire bead wire is used in engineeringcalculations when designing this type of reinforced product.8.2 Elongation of tire bead wire is taken into considerationin the design and engineering of tire beads because

23、of its effecton uniformity and dimensional stability during service.9. Apparatus9.1 Tensile Testing Machine, CRE (Constant-Rate-of-Extension) tensile testing machine of such capacity that themaximum force required to fracture the wire shall not exceed90 % nor be of less than 10 % of the selected for

24、ce measure-ment range. The specifications and methods of calibration andverification for tensile testing machines shall conform toSpecification D76.9.2 In some laboratories, the output of CRE type of tensiletesting machine is connected with electronic recording andcomputing equipment which may be pr

25、ogrammed to calculateand print the results for each of these desired properties.Because of the variety of electronic equipment available andthe various possibilities 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

26、 specimen doesnot occur at the gripping point, and slippage of the specimenwithin the jaws (grips) is prevented.10. Procedure10.1 Thermally age the specimen by 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 sca

27、le 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 testingmachine, nip to nip, to a gage length of 250 mm.10.4 Secure the specimen in the top clamp, exerting enoughpressure to prevent the specimen

28、 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 thespecimen 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

29、 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 jawbreaks continue to occur, insert a jaw liner such as an abrasivecloth between the gripping surface and the specimen in amanner so that the line

30、r 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.10.8 Elongation, the increase in gage length of a tensilespecimen, is usually expressed as a percentage of the originalgage length and can be

31、determined from the force-extensioncurve.10.8.1 When a greater degree of accuracy is required in thedetermination of elongation, an extensometer can be attachedto the specimen.10.9 Yield strength is the stress at which a material exhibitsa specified limiting deviation from the proportionality of str

32、essto 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) 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 th

33、e force-extension curvecorresponds to force R which is the yield strength. Should theforce-extension curve exhibit an initial nonlinear portion,extrapolate from the straight line portion to the base line. Theintersection is point O used in this section.11. Calculation11.1 Calculate the average break

34、ing force of the laboratorysample to the nearest 5 N.D4975 14211.2 Calculate the elongation to break from the force-extension curve to the nearest 0.1 %. Should the force-extension curve exhibit an initial nonlinear portion, extrapolatefrom the straight line portion of the curve to the base line. Th

35、isintersection 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 elongation.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 t

36、ests were performed as directed in TestMethods D4975, describe the material or product tested, andreport the following:12.1.1 The test results of each specimen and the laboratorysample average. Calculate and report any other data agreed tobetween the purchaser and the supplier,12.1.2 Date of test,12

37、.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 Test DataAn interlaboratory test wasrun in 1990 in which randomly drawn samples of fourmaterials were tested in 13 laboratories. Each laboratory

38、 usedtwo operators, each of whom tested two specimens of eachmaterial on two separate days.NOTE 2The bead wire products used in the interlaboratory evaluationwere of the following diameter and strength levels:Material Diameter Strength1 0.965 mm regular2 0.965 mm high3 1.295 mm regular4 1.295 mm hig

39、h13.2 PrecisionFor the property of interest, two averagesof observed values should be considered significantly differentat the 95 % probability level if the difference equals or exceedsthe critical differences given in Table 1.NOTE 3The tabulated values of the critical differences should beconsidere

40、d to be a general statement, particularly with respect to betweenlaboratory precision. Before a meaningful statement can be made con-cerning any two specific laboratories, the amount of statistical bias, if any,between them must be established, with each comparison being based onrecent data obtained

41、 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 numbers to each of the laboratories.13.3 BiasThe procedures in this test method for measur-ing breaking force, elongation, and yield strength have no

42、known 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-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 direct

43、ions at the same time untilfracture occurs.15. Significance and Use15.1 Complex stress and strain conditions, sensitive tovariations in materials, occur in a wire specimen during torsiontesting. The torsion test is a useful tool in assessing wireductility under torsional loading. Defective wire lowe

44、rs torsionresistance.16. Apparatus16.1 Torsion Test Machine, an automated drive apparatusthat allows a single-filament wire under light tension to betested in torsion. A counter is provided that registers thenumber of wire rotations to wire fracture.17. Procedure17.1 Thermally age the specimen by pl

45、acing 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 appropriate 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 eac

46、h 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 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 appli

47、ed 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 equipment and run until the specimen frac-tures. For wire sizes below 1.40 mm, use a rotation speed of 60FIG. 1 Force-Extension Curve for Determinati

48、on of YieldStrength by the Offset MethodD4975 1436 15 r/min. For wire sizes greater than 1.40 mm, use a rotationspeed of 45 6 15 r/min.NOTE 4Speeds in excess of these cause excessive specimen heatingand can cause inaccurate results.17.6.1 If the specimen fails within twice its diameter fromthe jaw e

49、dge it is considered to be a jaw break, and the resultshould be discarded and another specimen tested.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 4 4 22Multi-Material Comparisons11717 3121212 28499 7866 616 5 5 26Single-Material ComparisonsYield strength, N Group 1AGroup 2BGroup 1 Group 2 Group 1 Group 21195720612881214401446247410281 3 2658 720 830216116 5 14 7 26 2