Silocon bronze welding headers

Bought a welder, Eastwood Elite MP250i.
Mig, Tig, stick, 250 amp max. I heard about silicon bronze so i bought a couple of pounds.
$58! I had a large argon tank from forty years ago; still full of argon! Obviously i don't weld a lot.
I have . 030 Silocon bronze wire, and once i get some practice in it will work well for me. Here are pics of collecter parts i started on tonight. The bronze can be smoothed out or ground down very easily, important for my skill level

Go to Burns, and some of the other stainless header people, maybe some you tubes from guys who do a bunch of it. See what they are doing.

304 stainless should use 307L wire for most of the fab work. Small stuff. I bought a roll of .035 MIG 307 wire and use that, Same stuff as TIG wire. Tubes need to be back purged. If the joints are kept tight, you can actually fuse it using little filler.

SiBR is only used for the outside of the flange to tube joint. The silicon bronze is less tensile than the stainless. It's "softer" and has some give. It helps to keep the headers from cracking there while supporting them. It also has a lower melting point so you don't have to make the header material "wet" or melt it. It's more of a brazing process. Making the steel melt is way too hot for the silicon. And the outside doesn't need to be completely welded. The seal is the inside weld at the end of the tube. The silicone outside is a support/reinforcement.

Material is expensive. I would get some cheaper straight pieces and practice. Cutting, making perfect joints, setting up your back purge rig and your torch, and welding joints. It's a different animal than mild steel.

My headers are all mild steel. I definately need some practice. I plan on leaving a somewhat wide raised bead of weld so the tube welds will be plenty strong. Header wrap will be used also. I am using the mig gun.

Let me know when you want to meet up for templates.

When I was gainfully employed did quite a bit of stainless piping projects. TIG welding in place with piping up to 12" made back purging problematic. The fitters would use this painted on the back side of the weld prior to fitup. Worked like a charm. May be an alternative to back purging for these types of projects.

Solar Flux

You're obviously talking "tig" but the OP's reference to .030 wire would indicate he's using "mig".

As for using mig, you're using the wrong gas. Straight argon is for tig ... ONLY ... PERIOD. For mig you want a co2/argon mix. And for what you're doing I would suggest not trying to run a bead but rather a series of spaced tacks. You seem to have too much heat in your parts as well, cool off the tacks with compressed air.

I think you need to re read the original post.

I Would agree with a few people here...silicon bronze is not meant for anything structural. The only time it should be used on a header is on the out side of the flange. Everything else should be ER70S for mild steel or 308L for SS.

I have 045" silicon bronze tig rod. I've never tried it in a wire feed welder, but I couldn't imagine the results would be very good. Pretty solf to push through the liner for starters.

Silicon bronze is brazing when used correctly. If you're melting the base metal, it's too hot for the SiBR and it will crack.

I'm not a professional welder by any stretch of the imagination. I welded my 304 s.s. manifolds together with 308 wire and no back purging. Did have 75/25 Argon& co2 gas. They're still working and crack free after 11 years. Was I just lucky, or is the back purging really not that critical.

I am going to try Silicon bronze mig on a 20ga sheet metal project with .023 wire.
You have any issues with feeding the soft wire?

What he said… Absolutely correct. the first time i tried it, I was trying to “weld” with it. cracka shacka lacka.

[u][/u]…and it is absolutely miserable to cut/ machine.

This is what "sugaring" looks like when you don't purge the tube. Scabs, scale, damaged material. The weld is weaker. The outside weld doesn't run as nice and doesn't look as nice as one that has coverage on both sides either.

SS needs straight Argon.

The shorter the mig cable the better. It is recomended to use a liner of plastic(?) Or is it teflon? Ask one of the welder manufacturer techs. I run .030 wire and keep the cable to the mig gun as bend free as i can. It took some adjustment to get my deal going. I am using a steel liner.

.030 is some very heavy wire. I would for sure switch to .023. Makes a big difference.

The welder i bought doesn't have drive rollers available for . 023. .030 is the smallest the 250 will run.

Brazing is plenty strong, all the old time and even current SCCA race cars are brazed. Aircraft are brazed. Bicycles made with preposterously thin 4130 are brazed. S/F....Ken M

"Always avoid brazing 4130 steel. The reason to not braze chromemoly is that this steel has a definite grain structure that actually opens up at medium red brazing temperatures. When brazing alloy is melted onto the steel surface, it flows easily into the many small cracks and crevices in the chromemoly steel. Then, as the braze joint cools, the brass will not compress and it forces major cracks to form in the 4130 steel. Often, a brazed 4130 steel part will crack completely in two before your eyes as it cools."
Performance Welding, Richard Finch, c. 1997, pg. 130.


The only place SiBR is typically used on a race car today is putting sheet metal in and header flanges.

Aircraft were brazed - 100 years ago. Then TIG was invented. Some hobby planes may still be.

Conversation was stainless headers. Burns has some great header construction articles.

https://www.youtube.com/watch?v=fWF0zCcXR5A&t=3s

Don't know what type of welder you have. But You can get .023" rollers for a Miller 250.
Doug

Well that's pretty. And they may have reasons for doing that. But try to get a drag race chassis certified that's been put together like that.

I'm out.

Why? Tig welding would be faster and stronger.

Eastwood elite 250 MPI, thier newest and most powerful at 250 amps/ 60%duty cycle. For the money, 1400$, i consider it a nice unit. Has Mig, Tig, stick, no scratch start. But it would be nice to have the Tig option for aluminum. They do sell a spool gun for $209.00 though. Also another nice option would be a pulse weld feature for things like headers, etc

Been said here many times. Silicon bronze rod or wire is used to braze metal. It is anot a strong weld joint at all since the brazing process is not meltng base metal.

Since we like youtube here ya go. Nice visual explanation.

Al, thanks for posting the video. It confirmed my thoughts on how strong the SiBr would be.