1、Designation: B298 12 (Reapproved 2017)Standard Specification forSilver-Coated Soft or Annealed Copper Wire1This standard is issued under the fixed designation B298; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This specification covers silver-coate
3、d, soft or annealed,round copper wire, intended for use in electrical equipment, asfollows:1.1.1 Class AWire whose silver coating is at least 1.25 %of the total weight of the coated wire.1.1.2 Class BWire whose silver coating is at least 2.50 %of the total weight of the coated wire.1.1.3 Class CWire
4、 whose silver coating is at least 4.00 %of the total weight of the coated wire.1.1.4 Class DWire whose silver coating is at least 6.10 %of the total weight of the coated wire.1.1.5 Class EWire whose silver coating is at least 10.00 %of the total weight of the coated wire.1.2 Silver-coated wire havin
5、g different minimum percent-ages of silver by weight may be obtained by mutual agreementbetween the manufacturer and the purchaser. For informationpurposes the thickness of coating in microinches provided bythe percentages listed above is shown in Table 1 (ExplanatoryNote 1).1.3 The values stated in
6、 inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3.1 ExceptionsThe SI values for density, resistivity, andvolume are to be regarded as standard.1.4 The foll
7、owing precautionary caveat pertains only to thetest method section of this specification: This standard does notpurport to address all of the safety concerns, if any, associatedwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices and
8、determine the applicability of regulatory limitations prior touse. For specific precautionary statements see 8.4.1.2 andExplanatory Note 2.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Princi
9、ples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 The following documents of the issue in effect at thetime of reference form a part of this specification to the
10、 extentreferenced herein:2.2 ASTM Standards:2B49 Specification for Copper Rod for Electrical PurposesB193 Test Method for Resistivity of Electrical ConductorMaterialsB258 Specification for Nominal Diameters and Cross-SectionalAreas ofAWG Sizes of Solid Round Wires Usedas Electrical ConductorsE50 Pra
11、ctices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated Materials3. Ordering Information3.1 Orders for material under this specification shall includethe following information:3.1.1 Quantity of each size,3.1.2 Wire size, diameter in inches (see 5.
12、3 and Table 1),3.1.3 Class of coating (Section 1 and Table 1),3.1.4 Type of copper, if special (see 4.2),3.1.5 Place of inspection (see 9.1), and3.1.6 Packaging and Package Marking (Section 10).3.1.7 In addition supplementary requirements shall applyonly when specified by the purchaser in the inquir
13、y, contract, orpurchase order for direct procurement by agencies of the U.S.Government (see S1, S2, and S3).1This specification is under the jurisdiction of ASTM Committee B01 onElectrical Conductors and is the direct responsibility of Subcommittee B01.04 onConductors of Copper and Copper Alloys.Cur
14、rent edition approved April 1, 2017. Published April 2017. Originallyapproved in 1955. Last previous edition approved in 2012 as B298 12. DOI:10.1520/B0298-12R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
15、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. United StatesThis international standard was developed in accordance with internationally recognize
16、d principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14. Materials and Manufacture4.1 The material shall be silver-coated
17、copper wire (Ex-planatory Note 2), of such quality and purity that the finishedproduct shall have the properties and characteristics prescribedin this specification.NOTE 1The following specifications define copper suitable for use:Specification B49.4.2 Copper of special qualities, forms, or types, a
18、s may beagreed upon between the manufacturer and the purchaser, andthat will conform to the requirements prescribed in thisspecification may also be used.5. General Requirements5.1 Tensile PropertiesThe silver-coated wire shall con-form to the requirements for elongation prescribed in Table 1.No req
19、uirements for tensile strength are specified. For wirewhose nominal diameter is more than 0.001 in. (0.025 mm)greater than a size listed in Table 1, but less than that of thenext larger size, the requirements of the next larger size shallapply.5.2 ResistivityThe electrical resistivity of the coated
20、wireat a temperature of 20C shall not exceed 875.20 ohmslb/mile2.5.3 Dimensions and Permissible VariationsThe wire sizesshall be expressed as the diameter of the wire in decimalfractions of an inch to the nearest 0.0001 in. (0.0025 mm)(Explanatory Note 3). The coated wire shall not vary from thespec
21、ified diameter by more than the following amounts:Nominal Diameter, in.Permissible Variations inDiameter, plus and minusUnder 0.0100 0.0001 in.(0.1 mil)0.0100 or over 1 %5.4 Continuity of CoatingThe coating shall be continuous.The continuity of the coating shall be determined on represen-tative samp
22、les taken before stranding or insulating and shall bedetermined by the sodium polysulfide test, in accordance with8.4. Wire whose coating weight corresponds to a thickness lessthan 40 in. (0.00004 in.) shall not be subject to this test(Explanatory Note 4).5.5 Weight of CoatingThe weight of coating e
23、xpressed inpercent of the total weight of the wire shall be not less than1.25 % for Class A; 2.50 % for Class B; 4.00 % for Class C;6.10 % for Class D; and 10.00 % for Class E. When coatingsother than these classes are required, the weight of the coatingshall be not less than that specified. For eas
24、e of comparison, thethickness of coating for these classes has been included inTable 1 (Explanatory Note 4).TABLE 1 Tensile RequirementsDiameter,in.Area at 20CElongationin 10 in.,min, %Thickness of Coating, in. (For Information Only)cmils in.2Class A, 1.25% SilverClass B, 2.50% SilverClass C, 4.00%
25、SilverClass D, 6.10% SilverClass E, 10.00% Silver0.1285 16 510 0.01297 30 340 680 1 090 1 659 2 7200.1144 13 090 0.01028 30 303 605 970 1 477 2 4220.1019 10 380 0.008155 25 270 539 864 1 316 2 1570.0907 8 230 0.00646 25 240 480 768 1 171 1 9410.0808 6 530 0.00513 25 214 428 684 1 043 1 7100.0720 5 1
26、80 0.00407 25 190 381 610 930 1 5240.0641 4 110 0.00323 25 170 339 542 828 1 3570.0571 3 260 0.00256 25 151 302 483 737 1 2090.0508 2 580 0.00203 25 134 269 430 656 1 0750.0453 2 050 0.00161 25 120 240 383 585 9590.0403 1 620 0.00128 25 107 213 341 520 8530.0359 1 290 0.00101 25 95 190 304 464 7600.
27、0320 1 020 0.000804 25 85 169 270 413 6770.0285 812 0.000638 25 75 151 241 368 6030.0253 640 0.000503 25 67 134 214 327 5360.0226 511 0.000401 25 60 120 191 292 4780.0201 404 0.00317 20 53 106 170 260 4250.0179 320 0.000252 20 47 95 151 231 3790.0159 253 0.000199 20 42 84 135 205 3370.0142 202 0.000
28、158 20 . 75 120 183 3010.0126 159 0.000125 20 . 67 107 163 2670.0113 128 0.000100 20 . 60 96 146 2390.0100 100 0.0000785 20 . 53 85 129 2120.0089 79.2 0.0000622 15 . 47 75 115 1880.0080 64.0 0.0000503 15 . 42 68 103 1690.0071 50.4 0.0000396 15 . . 60 92 1500.0063 39.7 0.0000312 15 . . 53 81 1330.005
29、6 31.4 0.0000246 15 . . 47 72 1190.0050 25.0 0.0000196 15 . . 42 65 1060.0045 20.2 0.0000159 15 . . . 58 950.0040 16.0 0.0000126 15 . . . 52 850.0035 12.2 0.00000962 15 . . . 45 740.0031 9.61 0.00000755 15 . . . 40 660.0028 7.84 0.00000616 10 . . . . 590.0025 6.25 0.00000491 10 . . . . 530.00220.002
30、04.844.000.000003800.000003141010.4742B298 12 (2017)25.6 JointsNecessary joints in the wire and rods prior tofinal plating and drawing shall be made in accordance with thebest commercial practice. Joints made after plating shall not beallowed to remain in the final product.5.7 FinishThe coating shal
31、l consist of a smooth continu-ous layer, firmly adherent to the surface of the copper. The wireshall be bright and free from all imperfections not consistentwith the best commercial practice.6. Conformance Criteria (Explanatory Note 5)6.1 Any lot of wire, the samples of which comply with theconforma
32、nce criteria of this section, shall be considered ascomplying with the requirements of Section 5. Individualproduction units that fail to meet one or more of the require-ments shall be rejected. Failure of a sample group from a lot tomeet one or more of the following criteria shall constitutecause f
33、or rejection of the lot. The conformance criteria for eachof the prescribed properties given in Section 5 are as follows:6.1.1 ElongationThe lot shall be considered conforming ifthe elongation of each of the selected specimens is not less thanthe elongation value in Table 1.6.2 ResistivityThe electr
34、ical resistivity of each of the fourspecimens shall conform to the requirements of 5.2. Failure tomeet these requirements shall constitute failure to meet theresistivity conformance criterion.6.3 DimensionsThe dimensions of the first sample (Table2) shall conform to the requirements of 5.3. If there
35、 are nofailures, the lot conforms to this requirement. If there arefailures, but the number of these do not exceed the allowabledefect number, c2(Table 2), for the respective number of unitsin the sample, a second sample equal to n2shall be taken andthe total defects of the n plus n2units shall not
36、exceed theallowable defect number, c2. Failure to meet this requirementshall constitute failure to meet the dimensional conformancecriterion.6.4 Continuity of CoatingThe continuity of the coating ofeach of the eight specimens shall conform to the requirementsof 5.4. Failure of more than two specimen
37、s shall constitutefailure to meet the continuity criterion. If not more than twospecimens fail to meet the continuity criteria, eight additionalspecimens from the lot shall be tested, all of which shallconform to the continuity criteria. However, any individualproduction unit, the specimen from whic
38、h failed to meet thecontinuity criteria, shall be rejected.6.5 Weight of CoatingThe weight of coating of each of thefour specimens shall conform to the requirements of 5.5.Failure of more than one specimen shall constitute failure tomeet the weight criteria. If only one specimen fails to meet thewei
39、ght criteria, four additional specimens from the lot shall betested, all of which shall conform to the weight criterion.However, any individual production unit, the specimen fromwhich failed the weight criteria, shall be rejected.6.6 PackagingConformance to the packaging require-ments specified by t
40、he purchaser shall be determined inaccordance with Table 3. The number of units in the sampleshowing nonconformance to the requirements shall not exceedthe allowable defect number, c,inTable 3. Failure to meet thisrequirement shall constitute failure to meet the packagingconformance criterion.7. Den
41、sity7.1 For the purpose of calculating weights, cross-sections,etc., the density of the copper shall be taken as 8.89 g/cm3(0.32117 lb/in.3) at 20C (Explanatory Note 6). The density ofsilver shall be taken as 10.5 g/cm3(0.1 mil) (0.37933 lb/in.3).8. Test Methods8.1 Tensile Strength and Elongation:8.
42、1.1 No test for tensile strength shall be required.8.1.2 The elongation of wire with a nominal diametergreater than 0.0808 in. (2.052 mm) shall be determined as thepermanent increase in length due to the breaking of the wire intension (see Explanatory Note 7). The elongation shall bemeasured between
43、 gage marks placed originally 10 in. (242mm) apart upon the test specimen and expressed in percent ofthe original length.8.1.3 The elongation of wire with a nominal diameter equalto or less than 0.0808 in. (2.053 mm) may be determined asdescribed above or by measurements made between the jaws ofthe
44、testing machine. When measurements are made betweenthe jaws, the zero length shall be the distance between the jawsat the start of the tension test and be as near 10 in. (254 mm)as practicable. The final length shall be the distance betweenthe jaws at the time of rupture. The fracture shall be betwe
45、engage marks or jaws of the testing machine, depending onmethod used, and not closer than 1 in. (25.4 mm) to either gagemark or jaw.8.2 ResistivityThe electrical resistivity of the materialshall be determined in accordance with Test Method B193TABLE 2 Sampling for Dimensional Measurements and Surfac
46、e FinishNumber of Unitsin LotFirst Sample Second SampleAllowableNumber ofDefects inBoth Samplec2Number ofUnits inSample,n1AllowableNumber ofDefects inFirst Sample,c1Number ofUnits inSample,n2n1+ n21 to 14, incl All 0 . . .15 to 50, incl 14 0 . . .51 to 100, incl 19 0 23 42 1101 to 200, incl 24 0 46
47、70 2201 to 400, incl 29 0 76 105 3401 to 800, incl 33 0 112 145 4Over 800 34 0 116 150 4B298 12 (2017)3(Explanatory Note 8). The purchaser may accept certificationthat the wire was drawn from rod stock meeting the Interna-tional Standard for Annealed Copper in lieu of resistivity testson the finishe
48、d wire.8.3 Dimensional MeasurementsDimensional measure-ments shall be made with a micrometer caliper equipped witha vernier graduated in 0.0001 in. (0.0025 mm). Each coil shallbe gaged at three places, one near each end and one near themiddle. From each spool approximately 12 ft (3.7 m) shall beunre
49、eled and the wire gaged in six places between the secondand twelfth foot from the end. The average of the measure-ments obtained shall meet the requirements of 5.3.8.4 Continuity of Coating:8.4.1 Specimens:8.4.1.1 Length of SpecimensTest specimens shall eachhave a length of about 6 in. (152 mm). They shall be tagged ormarked to correspond with the coil, spool, or reel from whichthey were cut.8.4.1.2 Treatment of SpecimensThoroughly clean thespecimens by immersion in a suitable organic solvent for atleast 3 min; then remove and wipe dry with a c
