Active Standard ASTM B742 | Developed by Subcommittee: B02.05
Book of Standards Volume: 02.04
Historical (view previous versions of standard)
This specification covers fine silver electrical contact fabricated material. The forms covered are tubing, rod, wire, strip, and sheet for electrical contact applications. The sheet and strip shall conform to the required mechanical properties such as tensile strength, elongation, and hardness. The wire and rod shall conform to the required mechanical properties such as tensile strength and elongation. The material shall be produced by either hot or cold working operations. It should be finished by such cold working and annealing as may be necessary to meet the properties specified. All materials produced to this specification shall be inspected visually.
This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
1.1 This specification covers fine silver grade 99.9 % in fabricated form. The forms covered are tubing, rod, wire, strip, and sheet for electrical contact applications.
1.2 The electrical contact properties may vary dependent upon the method of manufacture (refer to 6.3).
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.4 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 Safety Data Sheet (MSDS) 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.
|Silver||99.90 min (by difference)|
|Silver and copper||99.95 min|
|Total others||0.05 max|
|Total of all impurities||0.10 max|
A Elements, such as phosphorus, sodium, and lithium are not natural impurities in this grade of silver and thus are not normally found in any appreciable quantities. However, since they may be detrimental for certain electrical contact applications, limits for these and other elements may be established by agreement between the purchaser and manufacturer. Refer to 7.2.
TABLE 2 Mechanical Properties of Sheet and Strip
Note—These hardness values are listed as “Typical,” because of the difficulty in establishing a range meaningful for all the thicknesses possible. If the purchaser desires hardness specifications, rather than tensile strengths, he shall reach agreement with the supplier as to the proper and suitable hardness scale and range for the particular size and form ordered.
in B & S
Strength, psi (MPa)
(51 mm), %
(see Note 1)
|Annealed||0||0||24 000 (165)||30 000 (207)||25||59 max|
|½ H||2||21||30 000 (207)||37 000 (255)||8||72|
|Hard||4||37||37 000 (255)||44 000 (303)||3||76|
|Spring||8||60||44 000 (303)||51 000 (352)||1||80|
TABLE 3 Mechanical Properties of Wire and Rod
in B & S
Strength, psi (MPa)
in 2 in.
(51 mm), %
|Annealed||0||0||24 000 (165)||30 000 (207)||25|
|1/8H||½||11||26 000 (179)||33 000 (228)||15|
|¼ H||1||21||30 000 (207)||37 000 (255)||4|
|½ H||2||37||39 000 (269)||46 000 (317)||4|
|Hard||4||60||42 000 (290)||49 000 (338)||2|
|Spring||8||84||46 000 (317)||54 000 (372)||1|
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
B413 Specification for Refined Silver
B476 Specification for General Requirements for Wrought Precious Metal Electrical Contact Materials
ICS Number Code 77.150.10 (Aluminium products)
UNSPSC Code 39121522(Electrical contacts)