Welding 304 Stainless headers without filler - issues?

[spv]

Are 0.065" thick 304 stainless headers likely to crack (in use on the car) if TIG welded without filler? I will be running an argon back purge and will ensure full penetration and a gold weld color. It seems that there are two schools of thought out there. I am not sure what to believe.

Note: this is for a supercharged engine.

 

[t100]

 

[king nero]

make sure they're 304 or 304L first. if they have a certain carbon content > 0.03%, I wouldn't try it without filler.

 

[steel 35]

If you get full penetration they will be (very strong) good luck on the no filler fit & 100% penetration that is an art. Try that 100% on a few test pieces to adjust perge pressure speed & Amps.

 

[racer7x]

I just read this yesterday. Might be helpful. http://www.jefflilly.com/fabrication/header-fabrication/

 

[Bobhdus]

The welds might be fine without filler using the procedure you mentioned. You might want to take into account that SS moves when hot. It moves a lot. You want to make sure that there will be no stress on the joints during expansion or contraction. That may be your biggest problem with a homogeneous weld. Often times, I use Solar Flux as opposed to back purging depending on the joint and I like it as I can put enough heat in there to know it has penetration. It will also support your weld on thinner materials. Back purging is usually the best but Solar Flux is another useful tool for the toolbox when welding SS.

 

[Frederik]

Pulse welding stainless pipe w/o filler is the standard right now in the food and dairy industry here. You need to cut the pipe very straight, and fit up has to be as tight as possible, i like for the pulse to be around 1Hz. If you do this, get the amperage right, and use adequate backing gas your welds should come out great! You should definitely use filler for attaching pipe to flanges though, and if fit up isn't perfect your probably going to need it in a couple of the pipe welds as well.