mig stainless quest.

[pinehillian]

hey all pine here, hey i been welding alot with my mig (lincoln) and i been using same wire that came with it basicaly for everything. (no alum) and i had to tack a piece of st steel the other day and it did work. inside welder it say must use stainless wire. now is that just so it dont rust or from damaging my welder or what. once in a while i would like to weld ss.---im using that np flux 9m sumptin sumptin. changing wire will get old. any tips or tricks to welding ss with this wire, thanx ahead

 

[kevbo22]

It will be because of oxidization. Normal wire isnt recommenced because it will rust and fail. Brittle too.

Use stainless steel wire and a tri-mix gas. However I know people who use low co2 argon mixes.

I would use high helium argon mix myself

 

[Kartorbust]

For Tig and Mig we used straight Argon with stainless wire in college. In production welding we used standard mild steel wire for mild steel to stainless steel, no idea on the gas, but I'm assume 90/10 mix. If it isn't too important standard mild steel wire will be fine.

 

[pinehillian]

although my mig can axcept gas but i dont use any. just little mics. repairs with conveiniant machine. i also stopped using my tig, wich ran off a ac dc stick welder with argon. couldnt get hang of it. (i was like a one armed paper hanger with the crabs) no pedal just my 3 hands and real sencitive outside. thanx guys

 

[Jfive]

They make Flux core stainless wire. Get a magnet and see if the stainless is magnetic or not. If it is then welding with regular er70 wire and gas should be fine if you don't mind a little rust. You'd have to use gas though.

 

[kevbo22]

This got me thinking enough to look it up. Here is one of my manuals recommended gas for ss.
Read a lot in welding forums and a 98/2 should be fine as well.

 

[Jfive]

There are quite a few guys that have Welded stainless 304l v band exhaust clamps to cast steel ls exhaust manifolds with no problems of cracking with regular er70 and 75/25 gas. These are heated up to 1500f at times with a full out run. Also the vibration and the weight the have on them proves its possible, although using the correct materials and methods is always best. I know with tig they want you to back purge to protect the inside as well as the outside while welding. That's why I use my 119.00 harbor freight arc welder DC invertor and stainless rods. No gas needed as its provided by the Flux.

 

[Randy H]

98/2 = spray transfer. High deposition process for thicker material. It'll really work your machine. No short circuit crackle. Just a pleasing hum. Lots of heat. Maximum distortion. Especially for SS. Joints need to be designed accordingly.

Any open root process with SS really needs a purging gas or a backing plate. You might be able to grind and cover your tracks, but not really legit.

 

[kevbo22]

I am not saying it cant be done with er70 wire and c25, or for that matter on a small project that you souldnt, as it has been done. Although, after some reading, I think c25 is pushing it. I would atleast use a 90/10 preferably a 98/2.

I think if you are going to be welding, and want to do a good job, or if you have to pass inspections, you should just do it right.

from lincoln:
you do not want to use a completely inert shielding gas, such as 100% helium or 100% argon for stainless steel MIG welding. The arc characterisitcs would be poor. Note: Do not confuse this recommendation with the recommended shielding gases for the Gas Tungsten Arc Welding or TIG process, which is 100% argon or 100% helium (or a mix of the two) for any type of base metal, including stainless steel. The arc dynamics are quite different with the TIG process than with the MIG process. In addition, you do not want to use the same type of shielding gas that you use with carbon steel wire, such as 75%Ar/25%CO2 or 100%CO2. Both carbon and oxygen from the shielding gas react with the stainless steel in the heat of the arc, resulting in some oxidization and reduction in corrosion resistance. The maximum level of oxygen or carbon dioxide that should be used in a shielding gas mix with stainless steel is 3% or 5% respectively.

a breakdown of why you would use a 90/7.5/2.5tri-mix:
co2 kept low minimize carbon absorption and assure good corrosion resistance
argon for the arc and fusion
high helium content provides significant heat input to overcome the sluggish nature of the stainless steel weld pool.

---------- Post added at 10:05 PM ---------- Previous post was at 10:04 PM ----------

98/2 = spray transfer. High deposition process for thicker material. It'll really work your machine. No short circuit crackle. Just a pleasing hum. Lots of heat. Maximum distortion. Especially for SS. Joints need to be designed accordingly.

Any open root process with SS really needs a purging gas or a backing plate. You might be able to grind and cover your tracks, but not really legit.

Spay transfer only if your in the 200amp range, probably higher.

 

[Randy H]

OK. I've never used a 98/2 mix that wasn't Argon and Oxygen. Always spray transfer. I can't remember what short arc or globular resulted in with that mix. If I was into a project I would TIG it or Stick it. If it was thick and was gonna take forever I would spray transfer with the biggest meanest machine available.

 

[kevbo22]

OK. I've never used a 98/2 mix that wasn't Argon and Oxygen. Always spray transfer. I can't remember what short arc or globular resulted in with that mix. If I was into a project I would TIG it or Stick it. If it was thick and was gonna take forever I would spray transfer with the biggest meanest machine available.

I'll second the spray transfer as Randy said, its a great process! A 250 amp will defiantly do spray. I have a hobart 210, not sure if it has the power to spray as I never tried it. my eastwood 250 will. I just know you need a big machine to do it. If you have the power in your machine, you should defiantly consider spray transfer for any material that is.

 

[supermanotorious]

this is from Welding Principles and Applications 6th ed