Welding 409 stainless??

[gearheads78]

Anyone ever welded 409 stainless with a MIG?
I ordered a bunch of mandrel bends from Magnaflow to build an exhaust system and they are made of 409 stainless. I alway thought you had to TIG stainless but was told the 409 grade can be MIGed. Anyone else heard this or done it? Any tricks?

[Matt@RFR]

If you asked for 409 at your local metal supply, they'd hand you a bottle of household cleaner. I have no idea why Magnaflow felt the need to use that alloy, when 304 or 321 would do everything you wanted, for probably less money, and they would use a filler alloy other than a catch-all alloy like 309. 409 is typically used in OE exhaust systems, but I have no idea what filler they use. It's not even listed in my stainless filler selection chart, but is close enough to 403 and 405 to suggest using ER309 for your filler. That's also the filler that's suggested for welding 403 and 405 to any other alloy, to include mild steel.

And yes, once again, you can weld stainless, magnisium, titanium, aluminum, nickel alloys, etc., etc. with MIG.

[myclone]

While Im no where near as knowledgable as Matt I have welded quite a bit of 409 when working with OE exhaust stuff. It welds just fine with a MIG and in all honesty I cant really tell much if any difference between welding 409 and mild steel exh stuff.

HTH

BTW, Matt you might be able to weld alum with a MIG but man I sure cant. Talk about some scary looking welds that I promptly hid in the bottom of the shop trash can before anyone else could see them!

[Matt@RFR]

Do you know what filler the OE's use for 409? By all indications, it's probably 309 or 310.

Matt you might be able to weld alum with a MIG but man I sure cant.

lol Nah, it is different than steels, but it's still the same process. Go do some dumpster diving (or run some more welds) and post pictures.

[myclone]

post pictures.

Why? Do you need a laugh today ? Seriously though I picked up a spool gun and gave it a shot just to see how I liked it. Yeesh, did it turn out rough looking.

Not to hijack the thread by any means but this may help other ppl by asking... When Im TIGing alum at times my filler rod seems to want to puddle on top of the parent metal and turns a nasty looking gray with a really rough (like 36 grit) finish to it. This is after thoroughly cleaning the parent metal with a non contaminated SS wire brush then wiping it down with acetone/clean rag. The filler rod is wiped with acetone as well since like most mere mortals I store the filler rod in the tube it comes in from the welding supply store.

Ive tried using a light arc to let the AC clean the area which seems to make no difference and the only thing Ive found that helps is when I switch to thicker material (1/2") which requires a LOT of heat I dont have this problem at all. Just the thinner stuff I cant throw a lot of heat into without melting the parent metal is what Im struggling with.