ASTM-B742 › Standard Specification for Fine Silver Electrical Contact Fabricated Material (Withdrawn 2019)
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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.
Scope
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.
TABLE 1 Chemical CompositionA
| Element | Weight % |
|---|---|
| Silver | 99.90 min (by difference) |
| Silver and copper | 99.95 min |
| Copper | 0.10 max |
| Nickel | 0.002 max |
| Cadmium | 0.005 max |
| Zinc | 0.005 max |
| Lead | 0.025 max |
| Iron | 0.005 max |
| Aluminum | 0.002 max |
| Bismuth | 0.001 max |
| 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.
| Temper | Reduction in B & S Numbers (Reference) | Percent Reduction (Reference) | Ultimate Tensile Strength, psi (MPa) | Minimum Elongation in 2-in. (51 mm), % | Typical (see Note 1) Hardness Rockwell, 15 T | |
|---|---|---|---|---|---|---|
| Minimum | Maximum | |||||
| 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
| Temper | Reduction in B & S Numbers (Reference) | Percent Reduction (Reference) | Ultimate Tensile Strength, psi (MPa) | Minimum Elongation in 2 in. (51 mm), % | |
|---|---|---|---|---|---|
| Minimum | Maximum | ||||
| 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 |
Keywords
contact; electrical contact; fine silver; silver; wrought; Electrical contact materials (silver alloy); Fabricated materials--specifications; Silver (electrical/electronic applications)--specifications
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Document Number
ASTM-B742-90(2012)
Revision Level
1990 R12 EDITION
Status
Superseded
Modification Type
Withdrawn
Publication Date
May 31, 2012
Document Type
Specification
Page Count
3 pages
Committee Number
B02.05