ASTM_B_631_-_93_2016.pdf

Designation:B63193(Reapproved 2016)Standard Specification forSilver-Tungsten Electrical Contact Materials1This standard is issued under the fixed designation B631;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers electrical contact componentsmade from silver-tungsten by powder-metallurgical proce-dures.1.2 This specification covers compositions within the silver-tungsten system normally specified by users of contacts.1.3 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 familiarwith all hazards including those identified in the appropriateData Safety Sheet(SDS)for this product/material as providedby the manufacturer,to establish appropriate safety and healthpractices,and determine the applicability of regulatory limi-tations prior to use.2.Referenced Documents2.1 ASTM Standards:2B328 Test Method for Density,Oil Content,and Intercon-nected Porosity of Sintered Metal Structural Parts andOil-Impregnated Bearings(Withdrawn 2009)33.Ordering Information3.1 Orders for this material under this specification shallinclude the following information:3.1.1 Dimensions(see Section 7).3.1.2 Chemical composition(see reference tables in theAppendix X1 as a possible guide).3.1.3 Physical properties(see Section 6 and Appendix X1 asguideline).3.1.4 Certification(see Section 13).3.1.5 Other features as agreed upon between the purchaserand manufacturer.4.Chemical Composition4.1 The material shall conform to composition limits asagreed upon between the manufacturer and purchaser.4.2 The chemical analysis shall be made in accordance withthe methods prescribed in the newest edition of the AnnualBook of ASTM Standards,or by any other approved methodagreed upon between the manufacturer and purchaser.5.Other Requirements5.1 The manufacturer and purchaser shall agree on qualifi-cation tests for determination of physical properties.5.2 The tests shall be performed on production parts,wherever practical or applicable(small size contacts do notlend themselves to accurate conductivity measurement).5.3 The tests shall be determined after consideration of thefunction of the part.5.4 The typical properties of the four most common types ofsilver-tungsten contacts are given in the appendix.6.Finishing of Contacts6.1 The material shall be finished by such operations asnecessary to meet requirements agreed upon by the maker anduser of the contacts(braze alloy backing,tumbling to polishsurfaces,special surface finish,silver-rich surface layer,cleaning,etc.).7.Permissible Variations in Dimensions7.1 Permissible variations in dimensions shall be within thelimits specified on drawings describing the contacts andaccompanying the order,or shall be within the limits specifiedin the purchase order.8.Workmanship8.1 The parts shall be free of defects in material or process-ing that would seriously affect their performance.9.Significance and Use9.1 Proprietary methods for manufacture of these materialsvary significantly among suppliers,and these methods influ-ence such properties as arc erosion,contact resistance,andtendency to weld in service.Since the performance of contactsin a device depends on numerous factors outside the contact1This 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 1,2016.Published May 2016.Originallyapproved in 1977.Last previous edition approved in 2010 as B631 93(2010).DOI:10.1520/B0631-93R16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 itself(opening speed,closing speed,contact pressure,contactbounce,environmental variations,assembly technique andvariations,etc.)this specification cannot ensure performancecontrol in the application.As part of the qualification on initialsamples it is recommended that the user functionally electri-cally test the materials for all devices applicable to thematerials use.This specification will provide a means for thecontact manufacturer and contact user to reach agreement onthe details of material to be supplied for a specific use andreasonable assurance that future lots will be similar in proper-ties and microstructure to the initial test or sample contactssupplie