View Full Version : Weld Stainless to Mild?

06-28-2008, 06:07 PM
Is it possible to weld Stainless steel material to mild steel. What process do you have to use? Any info would be helpful.

06-28-2008, 06:16 PM
Yes. MIG and TIG can do it from my experience. Filler metal depends on requirements. I use 316L when I TIG steel to SS.

06-28-2008, 06:34 PM
You can use any steel wire or rod to weld steel to SS, but the proper rod or wire would be ER 309...Bob

Jolly Roger
06-29-2008, 12:18 AM
With sticks you can use 7018 or 308/309. It all depends on what you want to do. Lincoln has some good info on this subject on their website.

06-29-2008, 11:30 AM
I do alot of this in waste water treatment work{stainless to mild}.I always use 309.

06-29-2008, 04:24 PM
Yes, as ^^ above, it is possible. I welded 30,000 stainless nuts onto car door latches once (talk about mental fatigue). Can't remember the filler (tig) I was given to use though.

06-29-2008, 09:34 PM
Use 309L to weld stainless to carbon...7018 will hold for awhile if it is burned in well...but will crack and break because the lack of fusion of disimular metals

06-29-2008, 11:39 PM
I have to disagree with you on the 7018, Jonesy.I've welded a bunch of 316 SS pipe to Grade B seamless carbon pipe used in waterflood systems. These floods were injecting produce water at 2500 to 3000 psi and none of the welds ever failed. Once in awhile the carbon pipe would corrode thru but the welds were still there.

Donald Branscom
06-30-2008, 11:08 PM
The correct filler for steel to stainless steel is 309 or 309L.

A long time ago a buttering pass was made with 310 then welded with 312.
309 replaced that method.

07-04-2008, 12:49 AM
I have to disagree with you on the 7018, Jonesy.I've welded a bunch of 316 SS pipe to Grade B seamless carbon pipe used in waterflood systems. These floods were injecting produce water at 2500 to 3000 psi and none of the welds ever failed. Once in awhile the carbon pipe would corrode thru but the welds were still there.

Well I certainly don't know everything...Id like to read some info on your process if you can get it...Ive welder some funky alloys together with wire that I have never heard of before...in my experience though,joining stainless to carbon was always done with 309

07-04-2008, 09:50 AM
in my world of constantly having everything inspected we use 309 wire to weld SS to mild. 7018 may hold but if you run the risk of the weld failing and cracking. Also just because you can do it does not mean its a good idea...like driving with your teeth...you can do it but its not a good idea. I am reasonably sure AWS does not approve of using 7018 to weld SS and mild. I know ALL of the CWIs I have ever dealt with sure don't approve.


07-04-2008, 03:49 PM
First let me say I'm not arguing with anyone that you shouldn't use the proper electrode or wire for the material you are welding. I never build any new work with 7018. I only used it for repairs in existing systems. If I was fabricating piping from SS I used 309 electrodes. We didn't use a lot of stainless. Each well had a SS meter run and some would have a SS change-over tying the injection line into the wellhead.

Jonesy, my process was very simple. I welded it just like carbon pipe but with a 7018 stringer so it was low hydrogen all the way. The first time I did this was in one of those " we gotta get this leak fixed" situations and I didn't have time to make a 100 mile round trip to a welding supply. Well, it worked just fine so the next time this happened I did it the same way. I was keeping seven different floods operating so I could observe how my repairs stood up.

I don't know if any of you have ever welded up leaks in a waterflood system injecting produce water or not. It almost always involves nasty water running out of what you are trying to weld. Usually in a mudhole of black, nasty stuff. A lot of times you are in a bell hole that is trying to fill up with the stuff and a lot of times you have a vacuum truck sucking up the mess just so you can work. I dreamed up a lot of unorthodox ways to get leaks repaired and I intended for them to stay repaired. Under these conditions you aren't interested in what the AWS or a CWI would have to say about what you were doing, just in getting the leak fixed and having it stay fixed. If the 7018 had failed I would have started carrying stainless rod but none of the welds ever did.

07-04-2008, 05:23 PM
Very true. When things need to get done NOW you do what you have to and worry about a "proper" fix later.


07-07-2008, 12:08 PM
309 stainless steel (SS) is generally the correct choice for welding 300 series stainless steel to carbon steel (CS), and the reason is that the chemistry of the weld metal mixture of SS and CS will affect the crystalline structure, hardenabilty, and weld cracking.

See this old thread: http://weldingweb.com/showthread.php?t=5686&highlight=stainless+steel+mild

07-08-2008, 06:56 PM
hey there guys i dont know alot about stainless welding procudres. but.. i have welded 1/8 316L to mild A36 before... heres a pic i got laying around...http://i112.photobucket.com/albums/n191/Rog273MX/P1000271.jpg

i have also welded another electrode and its been a year or two. but it was something like 3-16-2B ???? i know thats prolly wrong.. but it was something like that. it was 3/32 and it took forever!! to lay beads down. i would say the 316 in my opinon...

have a great day everyone...:)

07-08-2008, 07:20 PM

I'm curious, neither of those plates looks stainless to me, more like stainmore.

07-08-2008, 09:41 PM
the plate is A36 and i was using a stainless steel 316L electrode smaw. that was my first stainless experence haha.. it worked i guess. i really want to try stainless-to-stainless i heard that your puddle is alot smother and easier to cotrol VS mild steel to stainless. but like i said i wouldent know to much about it.

oh, and that rod i wasnt sure about in my last post, i was looking through my notes, and i belive i have it right this time. 16-8-b? if someone know what i am talking about please let me know if i am right.

i also trired this electrode called inconell 112. i belive that is how it is spelled... i am not sure about most of these electrodes i just was playing with them, and it was all stainless to mild steel...

have a great day
4runnin :)

07-21-2008, 12:49 AM
I have seen stainless welded to stainless with ER70S6 and it held better than the stainless with 309, and it was in a harsh environment, extreme heat 450 to 500 degrees F for 18 to 19 hrs then cooled with 150 degree water ( without any cool down time ) then washed with caustic and after that ran through a sanitize cycle. Yes the caustic finally won. The ones welded with the 309 would crack from the stress of not allowing enough cool down time I suppose.