Tig Welding 304

[Paul Irvine]

Hi,
I'm after what grade of filler rod to use on 304 tube, the pipe size is 100mm x2mm wall, one of our welders came back with 408 as a grade but I need some other views on this.
Background on the job is its a hovercraft exhaust, we used to make them all in 316 but due to cracking issues we want to move over to 304 on a new design.
The size of the craft is a bit larger that the one below.
Paul

 

[antonio costa]

Hi.
308 is what I would use.
Regards,
Antonio Costa

 

[AndersK]

This chart says 308 filler

Edit: Typing slower than Antonio

 

[penfold]

If you have cracking issues I'm not convinced moving to 304 will help much; it might be worth experimenting with galvanised steel, or if corrosion resistance is really vital then exotics like nimonic of some kind or even cupronickel. Also the design/layout/mounting may need going over, as if there are stress raisers even nimonics won't stop it tearing itself apart.

 

[milk]

I'd use 308. but was always under the impression any thing in contact with salt water should be 316 as it offers better corrosion resistance.

 

[Richard.]

308 is the "proper" choice but either 308/316 will be fine to weld 304.
316 does have higher corrosion resistance as milk rightly says but it's also higher strength than 308 which means lower ductility so you made a good move to try 304 if the 316 is cracking. So on that basis use the 308 as your filler.

 

[Tigman]

I concur 308 !

 

[Leetig]

Hi folks. Not trying to hijack this but to add to it. I've a exhaust job to do which consits of joining a link pipe from the standard headers,collector to a aftermarket end can on a er650 race bike. The advise I'm after is the standard parts are I'm guessing is 400 stainless (strong magnetic pull) that I need to weld to 304. What filler do ya recommend. I'm thinking 312 but would like some opinions thanks. Also will 316 filler be ok on the 304. It's just I have lots of it and don't want to buy 308 just for a few welds!

 

[Richard.]

I'm assuming it's a 409 or 421 ferrite grade lee. And taking into account it's got to withstand some high temp as it's a race bike exhaust. 307 would be a good choice for this I believe. 309 will join it but 307 is better for high temp application.

 

[Leetig]

Not sure of exact grade Richard but the new pipe will be 304.
Other question I have is apart from disconnecting battery is there anything I need to do to protect electrics? I've never welded on a vehicle before!

 

[antonio costa]

Richard really summed it up as usual. My choice would also be 307 since it's an high heat application.
I've done lot's of vehicle welding and usually disconnect the battery to be safe and put the ground clamp as close as I can to the place where I'm welding and never had a problem.

 

[Richard.]

Richard really summed it up as usual. My choice would also be 307 since it's an high heat application.
I've done lot's of vehicle welding and usually disconnect the battery to be safe and put the ground clamp as close as I can to the place where I'm welding and never had a problem.

^^^^^^^^^^^

 

[Leetig]

Thanks lads.