Welding 304 S/S exhaust

[Tinbasherdan]

That's rude langy, I like it

 

[Dimitri De Spiegeleer]

standard stainless exhausts are made from a ferritic variety of SS, needing the filler as posted before by TechnicalAl.
Aftermarket ones are mainly 304 or 316, thus a 316 filler would be your best bet. Purging is a necessity, not optional.

 

[Ben88]

So i 've been practicing on some 40 mm scrap pieces not purging them for now tho. Seems to be going well got some nice blues & golds coming out Apart from on the outside of the bends its coming out slightly dull tiny bit of rainbow effect, what can I do to improve this I think as the gas is hitting the apex of the joint and it's pushing the gas away from the joint. I'm using 1.6 tung with gas lense an a large ceramic.cheers

 

[Dimitri De Spiegeleer]

A trailing cup?
A home made one will work just fine, don't need to buy one with a separate Argon feed.

 

[Richard.]

You don't need a big cup or a trailing cup to produce shiny colourful stainless welds.
You will get this at 6lpm though a standard lens and a size 8 cup.
Heat input is the key to shiny stainless. If your welds are spread and dull try picking up the travel rate or perhaps your current is a little high. Don't waste gas trying to achieve it. Standard settings through a lens is fine.

 

[Richard.]

Biggest cup I own is an 8. This was done with a 7 at 6lpm. Standard lens set up. 1mm at 35 amps. Travel was the key here I didn't hang about.

 

[Ben88]

It was a no 6 or 7 shroud i used 6lpm

 

[Ben88]

This is what i got on some bits of scrap plate not changing anything but the amps

 

[Richard.]

Nothing wrong with those at all. Fillets look great.

 

[sixtwoeight]

Just been skim reading this thread and im still none the wiser as to whether back purging is necessary, some are saying absolutely necessary and then others showing pictures of quality work which hasnt been back purged...makes me think it isnt necessary? Iam genuinely interested as want to build a ss exhaust system eventually for my projects.

 

[Richard.]

The quality you see is on the face side which will look fine as it's been shielded nicely in a blanket of argon.
You won't however see quality on the inside of full pen stainless welds without a purge.
It will look black and scabby and is compromised. Everyone is entitled to there opinion on whether sugaring is acceptable. Imo it's a defective joint and there is a strong chance it will fail.

 

[Chris Stevens]

Most commercial producers of stainless car exhausts MIG weld them, less chances of cracking, and I would guess costs only about 1/10th of purged TIG...............

 

[Richard.]

Most commercial producers of stainless car exhausts MIG weld them, less chances of cracking, and I would guess costs only about 1/10th of purged TIG...............

And they are a ferrite type SS
The op is using grade 304.

 

[Chris Stevens]

Maybe unless its a show car, he should get the lower spec material? Would probably cost half the money to do.

 

[TechnicAl]

Maybe unless its a show car, he should get the lower spec material? Would probably cost half the money to do.

Its 430LNb..........cheap enough like you say but not very plentiful outside the exhaust factory........thats the problem

 

[zeppelin builder]

def purge it or get a tin of SOLARFLUX mix it with swarfega and apply lightly to back of joint before tacking/welding like a flux coating stops coking was developed for warbird welding ss