ASTM B631-93(2016)

Standard Specification for Silver-Tungsten Electrical Contact Materials

ABSTRACT
This specification covers electrical contact components made from silver-tungsten by powder-metallurgical procedures. The material shall conform to composition limits specified. The material shall be finished by braze alloy backing, tumbling to polish surfaces, special surface finish, silver-rich surface layer, cleaning, etc. Chemical analysis and physical test shall be made to conform to the specified requirements.
SIGNIFICANCE AND USE
9.1 Proprietary methods for manufacture of these materials vary significantly among suppliers, and these methods influence such properties as arc erosion, contact resistance, and tendency to weld in service. Since the performance of contacts in a device depends on numerous factors outside the contact itself (opening speed, closing speed, contact pressure, contact bounce, environmental variations, assembly technique and variations, etc.) this specification cannot ensure performance control in the application. As part of the qualification on initial samples it is recommended that the user functionally electrically test the materials for all devices applicable to the material's use. This specification will provide a means for the contact manufacturer and contact user to reach agreement on the details of material to be supplied for a specific use and reasonable assurance that future lots will be similar in properties and microstructure to the initial test or sample contacts supplied.
SCOPE
1.1 This specification covers electrical contact components made from silver-tungsten by powder-metallurgical procedures.  
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 the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Data Safety Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2016
• ICS: 77.120.99 - Other non-ferrous metals and their alloys
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.05 - Precious Metals and Electrical Contact Materials and Test Methods

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B631 −93(Reapproved 2016)
Standard Specification for
1
Silver-Tungsten Electrical Contact Materials
This standard is issued under the fixed designation B631; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Chemical Composition
1.1 This specification covers electrical contact components 4.1 The material shall conform to composition limits as
made from silver-tungsten by powder-metallurgical proce- agreed upon between the manufacturer and purchaser.
dures.
4.2 The chemical analysis shall be made in accordance with
1.2 This specification covers compositions within the silver- the methods prescribed in the newest edition of the Annual
tungsten system normally specified by users of contacts. Book of ASTM Standards, or by any other approved method
agreed upon between the manufacturer and purchaser.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Other Requirements
responsibility of the user of this standard to become familiar
5.1 The manufacturer and purchaser shall agree on qualifi-
with all hazards including those identified in the appropriate
cation tests for determination of physical properties.
Data Safety Sheet (SDS) for this product/material as provided
by the manufacturer, to establish appropriate safety and health
5.2 The tests shall be performed on production parts,
practices, and determine the applicability of regulatory limi-
wherever practical or applicable (small size contacts do not
tations prior to use.
lend themselves to accurate conductivity measurement).
5.3 The tests shall be determined after consideration of the
2. Referenced Documents
function of the part.
2
2.1 ASTM Standards:
5.4 The typical properties of the four most common types of
B328 Test Method for Density, Oil Content, and Intercon-
silver-tungsten contacts are given in the appendix.
nected Porosity of Sintered Metal Structural Parts and
3
Oil-Impregnated Bearings (Withdrawn 2009)
6. Finishing of Contacts
3. Ordering Information
6.1 The material shall be finished by such operations as
necessary to meet requirements agreed upon by the maker and
3.1 Orders for this material under this specification shall
user of the contacts (braze alloy backing, tumbling to polish
include the following information:
surfaces, special surface finish, silver-rich surface layer,
3.1.1 Dimensions (see Section 7).
cleaning, etc.).
3.1.2 Chemical composition (see reference tables in the
Appendix X1 as a possible guide).
7. Permissible Variations in Dimensions
3.1.3 Physicalproperties(seeSection6andAppendixX1as
7.1 Permissible variations in dimensions shall be within the
guideline).
limits specified on drawings describing the contacts and
3.1.4 Certification (see Section 13).
accompanying the order, or shall be within the limits specified
3.1.5 Other features as agreed upon between the purchaser
in the purchase order.
and manufacturer.
8. Workmanship
1
This specification is under the jurisdiction of ASTM Committee B02 on
8.1 The parts shall be free of defects in material or process-
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
ing that would seriously affect their performance.
B02.05 on Precious Metals and Electrical Contact Materials.
Current edition approved May 1, 2016. Published May 2016. Originally
approved in 1977. Last previous edition approved in 2010 as B631 – 93 (2010).
9. Significance and Use
DOI: 10.1520/B0631-93R16.
2
9.1 Proprietary methods for manufacture of these materials
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
vary significantly among suppliers, and these methods influ-
Standards volume information, refer to the standard’s Document Summary page on
ence such properties as arc erosion, contact resistance, and
the ASTM website.
3
tendency to weld in service. Since the performance of contacts
The last approved version of this historical standard is referenced on
www.astm.org. in a device depends on numerous factors outside the contact
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B631−93(2016)
itself (opening speed, closing speed, contact pressure, contact other reasons for requiring analysis for specific elements, then
bounce, environmental variations, assembly technique and agreement between manufacturer and purchaser for both limits
variations, etc.) this specification cannot ensure perform
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B631 − 93 (Reapproved 2010) B631 − 93 (Reapproved 2016)
Standard Specification for
1
Silver-Tungsten Electrical Contact Materials
This standard is issued under the fixed designation B631; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers electrical contact components made from silver-tungsten by powder-metallurgical procedures.
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 the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to become familiar with all hazards including those identified in the appropriate Material Data Safety
Sheet (MSDS)(SDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices,
and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
B328 Test Method for Density, Oil Content, and Interconnected Porosity of Sintered Metal Structural Parts and Oil-Impregnated
3
Bearings (Withdrawn 2009)
3. Ordering Information
3.1 Orders for this material under this specification shall include the following information:
3.1.1 Dimensions (see Section 7).
3.1.2 Chemical composition (see reference tables in the Appendix X1 as a possible guide).
3.1.3 Physical properties (see Section 6 and Appendix X1 as guideline).
3.1.4 Certification (see Section 13).
3.1.5 Other features as agreed upon between the purchaser
and manufacturer.
4. Chemical Composition
4.1 The material shall conform to composition limits as agreed upon between the manufacturer and purchaser.
4.2 The chemical analysis shall be made in accordance with the methods prescribed in the newest edition of the Annual Book
of ASTM Standards, or by any other approved method agreed upon between the manufacturer and purchaser.
5. Other Requirements
5.1 The manufacturer and purchaser shall agree on qualification tests for determination of physical properties.
5.2 The tests shall be performed on production parts, wherever practical or applicable (small size contacts do not lend
themselves to accurate conductivity measurement).
5.3 The tests shall be determined after consideration of the function of the part.
5.4 The typical properties of the four most common types of silver-tungsten contacts are given in the appendix.
1
This specification is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.05 on
Precious Metals and Electrical Contact Materials.
Current edition approved Oct. 1, 2010May 1, 2016. Published October 2010May 2016. Originally approved in 1977. Last previous edition approved in 20042010 as
B631 – 93 (2004).(2010). DOI: 10.1520/B0631-93R10.10.1520/B0631-93R16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
B631 − 93 (2016)
6. Finishing of Contacts
6.1 The material shall be finished by such operations as necessary to meet requirements agreed upon by the maker and user of
the contacts (braze alloy backing, tumbling to polish surfaces, special surface finish, silver-rich surface layer, cleaning, etc.).
7. Permissible Variations in Dimensions
7.1 Permissible variations in dimensions shall be within the limits specified on drawings describing the contacts and
accompanying the order, or shall be within the limits specified in the purchase order.
8. Workmanship
8.1 The parts shall be free of defects in material or processing that would seriously affect their performance.
9. Significance and Use
9.1 Proprietary methods for manufacture of these materials vary significantly among suppliers, and these methods influence
such properties as arc erosion, contact resistance, and tendency to weld in service. Since the
...