What type of weld/braze is this?

[debun]

There are two types, brass/bronze to stainless steel, and brass/bronze to what appears to be a copper tube. I'm trying to find suppliers with similar capabilities, but I don't know what kind of weld/braze this is, so I don't know where to start.

 

[MintJulep]

Vacuum-furnace brazing.

 

[unclesyd]

I was thinking along the same lines as posted by MintJulep or it was a paste solder job. The uniformity of the filler tends to eliminate any hand application. The only problem with furnace braze is that I can't recall a low temperature paste/preform brazing material that matches the color.

debun,
Can you tell how hard or scratch resistant the filler metal is?
A lead/tin based solder will be extremely soft while a high temperature solder will be appreciably harder.

MintJulep,
i don't know if you have ever seen a solder with
Cadmium used but this has that look of a Cadmium based solder metal. Do you are anyone else have an opinion?

 

[chicopee]

That looks like silver brazing by the color of the copper to the CI. Also it appears hard.

 

[tomwalz]

Similar capabilities are easy to find. Analyzing the current joint is going to be hard. Even spectrographic analysis will only be roughly approximate.

Were it my project I would just specify what I wished and put that out. Specifying the materials and the use, especially temperature and pressure, should do it unless it is highly unusual.

It almost looks like a braze alloy between the top part and the bottom assembly and solder between the bottom parts.

Should that be the case then you assemble the top part first at a higher temperature then the bottom parts at a lower temperature.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[MintJulep]

Cadmium generally isn't used in in vacuum-furnace brazing. Possibly in an inert-gas atmosphere rather than vacuum.

For a brass/bronze/copper base metals the typical fillers would be copper-nickel unless there was something special about the joint.

 

[debun]

How did they do the stainless to the brass/bronze? That looks like some sort of a laser braze.

 

[Capntom]

It looks like Silver Braze, Perhaps Bag-7 ? Pre-form filler wires are an excellent way to control the amount of filler in the joint. A reducing atmosphere, a positive pressure Hydrogen belt furnace would display this type of look on the finshed product. Its definately not torch brazed with flux, otherwise you would see a strong display of the copper coller caused from the flux. As mentioned different fillers with decreasing melting temps are an aid to multi-joint assemblies.
FYI, Brazing is above 840° F, Soldering is below that. Alloying ingredients control this transition stage as well as joint properties.

 

[griffengm]

T'were me, I'd call one of the major braze material mfgrs and get their input. If you explain that you are trying to identify processes and locate additional suppliers they will usually help on both counts. They know the reputation of their customers as well as customer capabilities. More work for the braze shop means more product sales. Shortens your search work by maybe 30-40%.

Griffy