1、Designation:B74290(Reapproved 2012)Standard Specification forFine Silver Electrical Contact Fabricated Material1This standard is issued under the fixed designation B742;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、 revision.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 Department of Defense.1.Scope1.1 This specification covers fine silver grade 99
3、.9%infabricated form.The forms covered are tubing,rod,wire,strip,and sheet for electrical contact applications.1.2 The electrical contact properties may vary dependentupon the method of manufacture(refer to 6.3).1.3 The values stated in inch-pound units are to be regardedas standard.The values given
4、 in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 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 become familiar
5、with all hazards,including those identified in the appropriateMaterial Safety Data Sheet(MSDS)for this product/materialas provided by the manufacturer,to establish appropriatesafety and health practices,and determine the applicability ofregulatory limitations prior to use.2.Referenced Documents2.1 A
6、STM Standards:2B413 Specification for Refined SilverB476 Specification for General Requirements for WroughtPrecious Metal Electrical Contact Materials3.Classification3.1 This specification presently defines only one grade offine silver,99.90%minimum silver.It differs from the Grade99.90 referred to
7、in Specification B413 in that the chemicallimits are slightly different.The reason for this is that Speci-fication B413 refers to“refined silver in cast bar form,”whereas this Specification covers fabricated forms.The prop-erties of silver are greatly dependent upon the amount and typeof elements pr
8、esent,up to 0.10%.3.2 Other types of silver containing appreciably lesseramounts of impurities,and those with additives for specialpurposes,are not covered by this specification,because themechanical properties can be appreciably different.4.Ordering Information4.1 Orders for material under this spe
9、cification shall includethe following information:4.1.1 Quantity(weight usually in troy ounces,or number ofunits).4.1.2 Name of material(fine silver).4.1.3 Temper.4.1.4 Dimensions;thickness,width,length,diameter,coilsize,or other pertinent sizes.4.1.4.1 Form of Material:sheet,strip,disks,blanks,wire
10、,shaped wire,or other.4.1.4.2 Form Furnished:flat lengths,coils,rod,straightlengths,or other.4.1.5 ASTM designation and date of issue.4.1.6 Additions to the specification and supplementaryrequirements,if required.5.General Requirements5.1 The provisions of Specification B476 shall apply to allmateri
11、als produced to this specification.6.Manufacture6.1 The materials used for making this product shall be ofsuch quality and purity that the finished material will conformto the requirements and properties prescribed in this specifica-tion.6.2 The material shall be produced by either hot or coldworkin
12、g operations.It should be finished by such cold workingand annealing as may be necessary to meet the propertiesspecified.6.3 After the initial shipment and approval has been made,the supplier must notify the purchaser prior to making anysignificant changes in process techniques,basic formulation,oro
13、ther factors that might affect the quality or the electrical1This specification is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct responsibility of SubcommitteeB02.05 on Precious Metals and Electrical Contact Materials.Current edition approved May 1,201
14、2.Published May 2012.Originallyapproved in 1985.Last previous edition approved in 2006 as B742 90(2006).DOI:10.1520/B0742-90R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,re
15、fer 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 States1 contact characteristics,such as weld resistance or erosion.Suchchanges in process shall be immediately brought to theattention o
16、f the purchaser for determination of the necessity forrequalification.7.Chemical Composition7.1 Material produced under this specification shall meet therequirements of chemical composition prescribed in Table 1.7.2 Byagreementbetweenthepurchaserandthemanufacturer,analysis may be required and limits establishedfor elements or compounds not specified in the table ofchemical composition.8.Mechanical Properties8.1 The material shall conform to the mechanical propertiesprescribed in Table 2 or Table