BVAu-4
BVAu-4 Technical Data
Uses
BVAu-4 can be used on any of the common ferrous, non-ferrous, and super alloys. Typical applications include brazing of electron tubes, vacuum tubes, wave guides in electronic industry. In aerospace industry, AMS 4787 can be used in brazing of fuel line assemblies and aero-engine components.
Brazing Characteristics
BVAu-4 wets a wide range of high temperature iron & nickel base alloys such as the stainless steels, A286, Inconel & Inconel X very well. It does not alloy excessively with these materials nor produce the severe intergranular penetration normally associated with the nickel based brazing alloys containing boron. A minimum brazing temperature of 1800°F (980°C) is suggested for furnace brazing in hydrogen or dissociated ammonia having a -40°F dew point or drier on 300 & 400 series stainless steels which do not contain additions of Ti or Al. Stainless steels of the 17-7 PH variety require dew points of -70°F or drier for furnace brazing. Brazing is also being conducted in inert atmospheres or in vacuum. Joint clearances of 0.0015” = 0.003” are normally suggested. Gold & nickel are completely soluble in all proportions at temperatures above 1490°F (810°C) & this specific composition (82Au/18Ni) represents the minimum in this system so that the solidus (melting point) & the liquidus (flow point) are identical. Normally, GB8218 would not be used for joining copper based & silver-based alloys. In addition, to having a flow point very close to the melting point of silver, & above that of the silver-copper eutectic, it would alloy quite readily with copper based alloys.
Specifications
BVAu-4 conforms to the following specification: AMS 4787, PWA 698, Unified Numbering System (UNS) P00827 and American Welding Society (AWS) A5.8 BAu-4/BVAu-4.
Available Forms
Wire, strip, engineered preforms, specialty preforms per customer specification, powder and paste.
Compare With
- AWS: BVAu-4
- Lucas: Premabraze 131
- UNS: P00827
Specifications
- Brazing Temperature Range High: 1840 F / 1004 C
- Brazing Temperature Range Low: 1790 F / 977 C
- Liquidus: 1740 F / 949 C
- Solidus: 1740 F / 949 C
Composition
- Au: 82%
- Ni: 18%
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