Nickel based filler metals are used to braze ferrous and
nonferrous high temperature base metals. These braze filler
metals are generally used for their strength, high temperature
properties and resistance to corrosion. Some filler metals can be
used up to 1800°F (980°C) for continuos service and 2200°F
(1205°C) for short time service. Nickel based filler metals melt
in the range of 1630 to 2200°F (890 to 1205°C), but can be used
at the higher temperature due to diffusion of the melting point
depressant elements from the filler metal into the base metal.
Joints made with nickel based filler metals tend to be more
brittle than joints made with other filler metals. Care must be
taken when using nickel filler metals containing boron on thin
sections due to the erosive nature of the molten filler metal and
the ability of this material to alloy with the base metal. Time
and temperature must be monitored very carefully to prevent the
molten filler metal from perforating the base metal.
| Filler Metals |
AWS A5.8 Classification |
Solidus °F/°C |
Liquidus °F/°C |
Comments |
| Hi-Temp 720 |
BNi-1 |
1790/977 |
1900/1038 |
Recommended for parts subjected to light stresses at
elevated temperatures. Good corrosion and flow
characteristics. |
| Hi-Temp 721 |
BNi-1A |
1790/977 |
1970/1077 |
Similar to above but of particular interest where
higher carbon content is not permissible. Slower flow
than Hi-Temp 720. |
| Hi-Temp 820 |
BNi-2 |
1780/971 |
1830/999 |
Widely used low melting filler metal for furnace
brazing aircraft parts, medical devices and other food
handling components. Good flow generous fillets, low base
metal penetration are characteristics of this filler
metal. |
| Hi-Temp 910 |
BNi-3 |
1800/982 |
1950/1066 |
Flows freely and less sensitive to atmosphere dryness
than the other filler metals. Better for tight/longer
joints. |
| Hi-Temp 930 |
BNi-4 |
1800/982 |
1950/1066 |
For stainless steels & Ni & Co base alloys
with thin sections--Jet engine parts and chemical
equipment. More sluggish and is better for wide gap
applications. |
| Hi-Temp 932 |
BNi-6 |
1610/877 |
1610/877 |
For stainless steels & Ni & Co base alloys
with thin sections--Jet engine parts and chemical
equipment. For uses that demand high temp properties and
good corrosion resistance at low processing temperatures. |
| Hi-Temp 933 |
BNi-7 |
1630/888 |
1630/888 |
Often used for brazing honeycomb structures,
thin-walled tube assemblies, and for nuclear applications
where boron can't be used. The addition of chromium gives
it better high temperature and corrosion properties than
Hi-Temp 932. |
Note: Recommended atmosphere for all above is
Dry Hydrogen (-60°F/-50°C) dew pt. or better; inert gasses;
vacuum.
Trimet material consists of two layers of braze
filler metal clad onto a core of copper. Trimets are used for
brazing carbides to ease the stresses that arise due to
differences in thermal expansion between the carbide and the base
metal when cooling from the brazing temperature. Trimet materials
are available in various filler metal compositions and different
ratios of filler metals to Cu. Trimet selection is dependent upon
base metals, service temperature and carbide size. Brazing of
small carbides (1/2 inch square (12.7mm) or less) may not require
the use of a Trimet, but its use on larger pieces has proven very
beneficial in preventing cracking and warpage of the carbide.
| Filler Metal |
Solidus °F/°C |
Liquidus °F/°C |
Formulation |
| Trimet 245 |
1260/680 |
1290/700 |
Braze 495 on both sides of copper in 1-2-1 ratio. |
| Trimet 258 |
1170/630 |
1270/690 |
Easy-Flo 3 on both sides of copper in 1-2-1 ratio. |
| Trimet 259 |
1220/660 |
1305/705 |
Braze 505 on both sides of copper in 1-2-1 ratio. |
Carbide Tool Tips:
Brazing Materials Selection Chart
| General Group |
Recommended
Brazing Filler Metals
| Small carbides (0.5 sq. in., 12.7mm) |
Large Carbides* (Greater than 0.5 sq.
in., 12.7mm) |
|
Recommended Fluxes** |
Remarks |
| Tungsten Carbide (WC) with cobalt
binders. WC with moderate additions of Titanium Carbide
(TiC), Tantalum Carbide (TaC) or Niobium (Columbium)
Carbide (NbC), with cobalt or nickel binder
|
| Easy-Flo 3 |
Trimet 245 |
| Braze 252 |
Trimet 258 |
| Braze 403 |
Trimet 259 |
| Braze 404 |
|
| Braze 495 |
|
| Braze 505 |
|
| Braze 580 |
|
| Hi-Temp 080 |
|
| Hi-Temp 095 |
|
| Hi-Temp 548 |
|
|
| Handy Flux |
| Handy Flux Type B-1 |
| Handy Hi-Temp Flux Boron Modified |
| Handy Flux Type Hi-Temp M |
|
The presence of nickel and manganese in
th e filler metals improves wettability. Braze 403 and
404 are sluggish alloys with long melting ranges. They
Produce relatively thick joints which help to relieve
residual stresses in the joint. |
| Wc with high percentage additions of TiC, TaC, or
NbC, and cobalt or nickel binder. Complex carbide
including chromium and molybdenum with nickel and/or
cobalt or steel binders
|
| Braze 404 |
Trimet 245 |
| Braze 495 |
|
| Braze 580 |
|
| Hi-Temp 080 |
|
| Hi-Temp 095 |
|
|
| Handy Flux Type B-1 |
| Handy Hi-Temp Flux Boron Modified |
| Handy Flux Type Hi-Temp M |
|
The presence of nickel and manganese in
th e filler metals improves wettability. Braze 403 and
404 are sluggish alloys with long melting ranges. They
Produce relatively thick joints which help to relieve
residual stresses in the joint. |
Trimets are also useful for brazing aluminum bronze/steel,
preventing the diffusion of aluminum to the steel interface. They
are effective for joining sintered powder parts and wire mesh
assemblies where wicking is objectionable and restricted flow is
desired.
* Alloy to be brazed
** Handy dispensable fluxes are recommended for use in
automated brazing applications.
