mig welding stainless

By - Date 07-31-2005 20:36

Rich,
You can manufacture a car exhause system using 316 SS, and can be welded quite easily with MIG, but not when using "ordinary mild steel". Most car manufacturers use Ferritic grade 409 for car mufflers and exhaust systems. I cannot imagine why anyone would even want to attempt to weld a stainless steel with a carbon steel electrode.

Chuck

By richy Date 07-31-2005 21:48

The carbon steel mig wire welds allow some flexability at the joints that prevent the brittle 316 s/s from fracturing , same as why motor cross frame builders used to braze steel tube frames together ????????? (apparentely)... the cheaper grade s/s that isnt so prone to cracking and is tig welded isnt so resilient to corrosion , they last for years but still corrode in the end ?? .316 though brittle lasts a lot longer , and corrosion at the joints isnt badly affected by using carbon steel due to thickness of the mig weld bead which also would take years to corrode through .......this is what ive been informed ??? is it bull ??

By - Date 07-31-2005 22:41

Richy,
I don't even know where to start on a thread like this....Personally, I disagree with virtually everything you talk about here. I've been dealing in stainless steel welding, technology, and engineering for nearly 35 years and have never heard anything about welding SS with a carbon steel filler metal because it allows more flexability at the joints. I'm not even sure what you're talking about. Then, you talk about the carbon steel preventing the "brittle" 316 joints from fracturing. Actually, a 316 SS has good ductility and elongation factors. Are you really suggesting that motor cross builders actualy braze SS tubes with carbon steel? Then, your next sentence about "cheaper grade s/s that isn't prone to cracking...etc., etc." totally makes no sense to me. Then, "....the corrosion at the joints isn't badly affected by using carbon steel due to the thickness of the mig weld bead would also take years to corrode" is a totally false statement. What in the world does the thickness of the mig weld bead using carbon steel to weld 316 SS have to do with the corrosion factor? Even if you were successful at welding a 316 SS with a carbon steel filler, it would be the weakest part of the weldment, and have the least amount of corrosion protection. You asked "is it bull?" Well, I think that is putting it mildly. When I read both of your threads, I asked myself, "Is this candid camera?" That is how ridiculous it sounds to me. Not trying to sound disrespectful, but someone has been messing with you.

Chuck

By richy Date 08-01-2005 07:52

Ok , many thanks for the information, its nice to have other opinions on the subject.
sometimes its so difficult to get the facts, as sometimes people tell you whats worked for them or was just luck ?
I did think the info was questionable and to be safe putting it to this forum has confirmed that it,s best to stick with the proven techniques.
Not being a proffesional welder i need as much advice as posible.
when i inquired about building a exhaust , this was the bull given to me by the materials supplier ?
Many Thanks

Richy

By - Date 08-01-2005 11:36

Richy,
Regarding your questions, I think it goes beyond "opinions" and gets into metallurgical facts. There is a huge difference in the two. If you got all this crap information form your distributor/materials supplier, I suggest you start looking for another supplier. Giving out that kind of information, if you are sure that is what he said, can ruin him and put him in a liability bind.

Chuck

By jon20013 (*****)

Date 08-01-2005 13:14

I have to agree completely with Chuck. While it is entirely possible to weld stainless steel with plain jane mild steel filler metal the resulting weld (even if it looked good on completion) would be a metallurical mess and accelerate the corrosion of the stainless steel leading to a rapid failure of the joint. Sounds like you need to find a better source of information.

By - Date 08-01-2005 13:25

Good morning Jon,
How is it going in the great state of Michigan? I'm leaving for the airport in a few minutes for Tampa Bay for some meetings regarding stainless steel welding with flux core. It can't be too intense since FCAW is about the easiest process when welding SS.
Anyway, thanks for the support. You know, I'd be very interested to know what materials supplier gave Richy all those "facts".
Have a great day !!! Talk to you soon...

Chuck

By richy Date 08-01-2005 16:44

we dont have the same liability rules in the UK as the USA , anyone can be an expert here without a scrap of evidence ?
I guess the supplier was just happy to offload me with a load of exspensive 316 bends etc , when i could have saved loads using lesser materials, anyhow i have got some dissimilar filler wire and going to tig myself an exhaust , if it all cracks up after use then i will know .

cheers

By jon20013 (*****)

Date 08-01-2005 16:48

Hey, Chuck! Michigan has been absoltely gorgeous the past few days, couldn't ask for much nicer weather but now that August is here, my thoughts have already turned to "better get the snowblower tuned up!" and yep, it's in at the mechanics as I write!

By techwelder Date 08-01-2005 20:35

Why don't you just purchase a 2lbs. spool of 316L Stainless welding wire, a bottle of AG 90 (90% Helium, 10% Argon) and weld it.

By - Date 08-03-2005 13:16

A much cheaper and more recommended gas would be a 98%argon/2%oxygen for this shielding. Helium is 10X lighter than argon and does not provide the same coverage unless you crank up the volume, then there is the good possibility of causing a vortex effect in the shielding. Especially in MIG welding in the flat position, argon is heavier and gives better coverage and the 2% oxygen is only there for arc stability.

Chuck

By - Date 08-03-2005 13:18

One more thing, purchasing a spool of 316LSi is a better choice, also. The higher silicon gives a better weld bead appearance, has better fluidity, and eliminates the spatter.

Chuck

By weldette (*)

Date 08-14-2005 20:07

Why not use a stainless pulse?

By - Date 08-16-2005 16:50

That is certainly an option if one has the proper equipment.