Brazing Brass to 304 stainless

[BobsTheBoss]

I'm trying to braze a 2" thick X 5.44 dia. ring to a 1.5" sch 40 type 304 S.S. pipe. I'm using propane & oxy. with a #6 tip, the rod is Harris flux coated low fuming bronze, AWS spec. A5.8 RBCuZn-C. I can't seem to get this to work, the brass is just turning black & the Stainless gets a white coating on it. The rod isn't flowing to either base metal. Any help would be great. Thank's in advance.

Bob
On-Site Welding & Fabrication

 

[unclesyd]

It sounds like your are not getting hot enough or you may have a leaded brass. Your ring is pretty good heat sink.

When we had to braze any Cu alloy to SS the preferred method was to use TIG with a Silicon Bronze filler metal with no flux.

 

[tomwalz]

How are you cleaning the parts before brazing?

Flux coated rods can be great but they are designed to prevent oxidation of the braze alloy. You are getting oxidation of the brass and stainless as well. It sounds like you might want to flux the two parts as well.

That is a big mass and area to heat particularly with a single torch.

We would aggressively clean with wire brush or sanding. Then clean with a caustic cleaner. (Others use a solvent successfully.) Then we would bend the braze alloy into ring to fit the joint. Heavily flux everything then heat until the braze alloy melts. Use a couple of fan torches if you can.


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.