ASTM B628-98(2021) PDF

Overview

ASTM B628-98(2021): Standard Specification for Silver-Copper Eutectic Electrical Contact Alloy provides internationally recognized guidelines for the composition, manufacture, and quality assurance of 72% silver-28% copper (eutectic) alloys. This standard applies to rod, wire, strip, and sheet materials intended for use in electrical contacts, ensuring reliable electrical and mechanical performance. Developed and maintained by ASTM, this standard is widely referenced in the production and procurement of precious metal electrical contact materials in various industries.

Key Topics

• Material Composition: Specifies a silver content of 71.0-73.0% by weight, with the balance being copper. Strict limits are set for impurities, such as zinc (max 0.06%), iron (max 0.05%), and other trace elements, ensuring high purity and consistent alloy performance.
• Manufacturing Processes: Outlines permitted finishing operations, including cold working, heat treatment, annealing, turning, grinding, and pickling. These processes are used as needed to achieve the required mechanical and electrical properties.
• Mechanical Properties: Defines requirements for ultimate tensile strength, elongation, and hardness for various tempers and product forms (rod, wire, strip, sheet). Standardized testing at room temperature ensures uniform evaluation.
• Quality Assurance and Testing: Covers inspection protocols such as visual examination (10× magnification), dimensional checks, hardness or tensile testing, and chemical or spectrographic analysis. Ensures material meets all prescribed criteria.
• Safety and Compliance: Emphasizes the user's responsibility to follow appropriate safety, health, and environmental procedures and comply with relevant regulatory requirements, including referencing the Safety Data Sheet (SDS).

Applications

ASTM B628 eutectic silver-copper alloys are essential in industries where reliable electrical contacts are required. Typical applications include:

• Switches and Relays: Utilized for their excellent conductivity, wear resistance, and low contact resistance, making them ideal for high-performance switching devices.
• Electrical Connectors: Used in connectors and terminals that demand high durability and consistent electrical properties.
• Industrial Controls: Commonly employed in control systems and automation where dependable electrical contact function is critical.
• Telecommunications Equipment: Integral to contact systems that require both high conductivity and mechanical strength.
• Aerospace and Defense: Accepted for U.S. Department of Defense use, servicing specialized applications with stringent reliability needs.

The specified alloy balances conductivity, resistance to arc erosion, and physical robustness, supporting long service life in demanding electrical environments.

Related Standards

Implementing ASTM B628 often involves consideration of additional ASTM and regulatory standards, including:

• ASTM B476 - General Requirements for Wrought Precious Metal Electrical Contact Materials: Sets broader guidelines applicable to all precious metal contact materials.
• ASTM B277 - Test Method for Hardness of Electrical Contact Materials: Details standardized methods for measuring material hardness.
• U.S. Federal Standards:
  • Fed. Std. No. 102: Preservation, Packaging, and Packing Levels.
  • Fed. Std. No. 123: Marking for Shipment (Civil Agencies).
• Military Standards:
  • MIL-STD-129: Marking for Shipment and Storage.
• International Trade: Developed in accordance with WTO TBT principles, promoting global trade and compliance.

Keywords: ASTM B628, silver-copper eutectic alloy, electrical contacts, precious metal alloys, conductivity, mechanical properties, quality assurance, electrical connectors, ASTM standards.

By adhering to ASTM B628-98(2021), manufacturers, suppliers, and users ensure that silver-copper alloys meet stringent quality and application requirements, supporting efficient, reliable, and safe electrical systems across diverse industries.