AMS 4777

AWS: BNi-2

AMS 4777 is a nickel-chromium-silicon-boron-iron brazing alloy with low joining temperature. It provides high temperature joint strength plus oxidation, corrosion, and abrasion resistance on thick sections of stainless steel, ductile nickel, and cobalt base alloys. Typical applications would include structural members in jet engines, turbines, chemical processing and nuclear equipment (not exposed to radiation), requiring lower brazing/heat treatment temperatures.

Available Forms

Foil, Preforms, Powder and Paste

Characteristics

Fast heating should be employed to avoid liquation (melting and flow of only part of the brazing alloy). AMS 4777 will flow into long, narrow joints, particularly at the higher brazing temperature, in reducing atmospheres (- 60F dew point or lower) or inert atmospheres (-80F dew point or lower). In atmosphere brazing, base metals containing more than 0.5% aluminum and/or titanium are often nickel-plated (0.0005 in. to 0.0015 in. thick depending upon brazing temperature and cycle), if difficulties in wetting and bonding are encountered. On thinner sections or less ductile base metals, brazing should be done at the low end of the brazing range with small clearances, fast heating/cooling cycles, and a minimum quantity of brazing alloy. Recommended joint clearance at brazing temperature for AMS 4777 is 0.001 in. – 0.004 in. (0.03 mm – 0.10 mm).

Properties

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. Joint ductility, strength and high temperature properties, and alloy re-melt temperature, increase with increasing temperature and heating cycles, and decreasing joint clearances. The hardness decreases, due to diffusion of the boron onto the base metal and greater brazing-alloy/base-metal alloying.

Specs

American Welding Society (AWS)

BNi-2

Solidus

1780 F / 971 C

Liquidus

1830 F / 999 C

Disclaimer

The information and recommendations contained in this publication have been provided without charge & compiled from sources believed to be reliable and to represent the best information available on the subject at the time of issue. No warranty, guarantee, or representation is made by the Prince and Izant Company, Inc. as to the absolute correctness or sufficiency of any representation contained in this and other publications; Prince and Izant Company, Inc. assumes no responsibility in connection therewith; nor can it be assumed that all acceptable safety measures are contained in this (and other publications, or that other or additional measures may not be required under particular or exceptional conditions or circumstances.

AMS 4777 AWS: BNi-2

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