Silver Braze 72
Silver Braze 72 Technical Data
Silver Braze 72 is generally used to join silver, copper and nickel base alloys in reducing or inert atmospheres or vacuum. It is also widely used to join metallized ceramics to metals in vacuum. The VTG version of Silver Braze 72, is designed for all types of moderate temperature vacuum systems and particularly where maximum precautions must be taken to insure the presence of only a minimum amount of detrimental volatile impurities.
Silver Braze 72 (& VTG) is the silver-copper eutectic composition and in melting it acts like a metallic element, i.e. it melts completely at a single temperature, thus it will quickly flow into long narrow joints. On either silver base of copper base alloys, Silver Braze 72 (& VTG) exhibits a decreased fluidity and an increased re-melt temperature due to the solution of either silver or copper in the eutectic. Brazing time and temperature should be minimized to prevent excessive diffusion and erosion of the base metal.
This filler metal has limited wetting ability on iron and/on nickel base alloys. The wetting ability it does have is derived from its copper content. Both iron and nickel have practically no solubility in silver, while nickel is readily soluble in copper and the solubility of iron in copper is sufficient to provide wetting. It is an observed fact that the wetting obtained in good hydrogen atmospheres is superior to that derived from flux protection.
Properties of Brazed Joints
The properties of a brazed joint are dependent upon numerous factors including base metal properties, joint design, metallurgical interaction between the base metal and the filler metal.
Silver Braze 72 conforms to American Welding Society (AWS) A5.8/A5.8M BAg-8, VTG version Grades 1 and 2 conform to BVAg-8
Wire, strip, engineered preforms, specialty preforms per customer specification, powder and paste.
- AWS: BAg-8
- Lucas: Silvaloy 720
- Morgan/Wesgo: Cusil
- PI: Silver Braze 72
- UNS: P07720
- Brazing Temperature Range High: 1535 F / 835 C
- Brazing Temperature Range Low: 1435 F / 779 C
- Liquidus: 1435 F / 779 C
- Solidus: 1435 F / 779 C
- Ag: 72%
- Cu: 28%
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