Mig welding stainless to normal steel

[Tractorguy24]

Hello,
Newbie here,
I got some work lights for my backhoe and would like to MIG weld them to the roof which is "normal" steel. The brackets that came with the lights are stainless. Can I, Using "Normal" mig wire, weld the bracket on my backhoe's roof? It wouldn't really matter if the weld and/or bracket would rust. Would match the rest of the machine
Thanks!

 

[Shield Arc]

I would use 309 stainless steel wire, with helium + argon + Co2 gas mix.
But that gas mix is costly. I would just pick up some 3/32-inch 309 stainless steel rod, and tack the lights on.

 

[yomax4]

I'd say ditto to the SS stick but yes you "could" use standard mig wire but you would need to paint the welded area or take the light off and paint the whole bracket afterward.

 

[CuzCumminsGuy]

If you could, MIG weld you a regular bracket on your piece of equipment, then bolt the stainless steel bracket to the mild steel bracket that you've MIG welded. This way, you can always take the bolts out and go another route in the future if you wanted to, and you would only have money in a few bolts and nuts and a couple of pieces of mild steel metal that are MIG welded on. You wouldn't need to purchase any 309 SS rods or wire, or the expensive gas for the SS MIG wire.

 

[yomax4]

Great idea. But you can weld stainless to steel with S6 wire and regular 75/25 gas. I do like the bracket idea too but no matter what you weld to what, painting would still have to be done. I vote bracket 1st. Bolt on light. If the light gets torn off like it would at my place. Unbolt and replace same or different type.

 

[CuzCumminsGuy]

Yeah, I know what you're talking about. I've been a certified pipe welder since '83, as my stepdad was tearing off cheap lights from flatbed trailers, so I got a piece of 6 inch square tubing, 3/8 inch wall thickness, then welded some extensions on it that were 2 inch schedule 80 carbon steel couplings and welded them to the side of the trailer. Found some preforated stainless steel plate for rear covers and bolted them on. Thought these would be bullet proof, as I had no idea he would back into as many things that he did! He wanted to know if I could fix them, so I told him 'Yeah, the best way would be for him to let someone else drive!'

When I TIG welded a lot, I used to use ER70S-6 TIG wire all the time, when everyone else around here was using the cheaper S2 wire. Man, I tell you, that Miller Dynasty 300 machine is top of the line for a welding machine!

 

[LD1]

Probably alot of better ways to do it as everyone else mentions. But yeah, you most certainly CAN weld stainless to mild steel with plain ole mig wire

 

[Billself]

Done this myself and yes i did use regular old mig wire kept everything the same on the welder and just went to town welding them up worked fine so far been about four years now just painted it when i was done

 

[CuzCumminsGuy]

Well, even though I was a certified pipe welder in a specific area on a specific metal, it sometimes doesn't add up to a hill of beans in the real world, when if all one has is what they have to work with. I'm not one who knows it all and can always learn something new, and just have! And I really do appreciate you guys sharing this with me, as it's a lot cheaper using what you already have to fix something such as a bracket than to go purchase something that is more expensive that you may only use once!

I remember back in the 80's when I was working up in Maine, when a pipe helper who I had become a friend with and helped him to go from a laborer to a helper position, came to me and he asked me if he could use my oxy-acetylene cutting torch to cut a piece of stainless steel plate. (I thought to myself, "Ok, this is gonna be interesting") so I said "Sure, go ahead brother". He fired up the torch and started getting the piece hot so he could cut it. Everytime he would attempt to cut the plate, it would just melt it a little, as I was laughing, then he would turn and look at me and I would then have a straight face.

He did this several times until I couldn't resist it any longer, as when he turned and looked at me the last time I was laughing so hard that tears were coming from my eyes! I can't repeat on this forum what he said, but he wanted to know what was wrong. I then said, "You can't cut stainless with that torch and make a straight cut, you need to use a plasma arc cutter". He said, "Well why didn't you tell me that"? I said, "Because you only asked me if you could use my torch"! He said a few more choice words, and we both laughed about that for several months. But he was happy that he was making more money as a helper than just a laborer, as he turned out to be a good friend.

 

[Gary Fowler]

I was the welding supervisor on an ASME Section 8 boiler fabrication job and a nozzle coming off the steam drum showed to be a carbon steel (A106 gr b) 2" pipe with a 316L inserted liner. We had to make up weld data cards for every weld on this job and the weld procedure directed us to weld it with ER70S-2 which the welder did all the way with TIG. Later as I was talking to the welder, he said "You know that nozzle off the drum sure is shiny for it to be carbon steel so I laid down on my back and shimmied under the drum to take a look. Sure as heck it was stamped 316L.

I notified the Shell (owner )QC dept of the error on the drawings and the wrong procedure used to weld the Carbon steel pipe to the SS nozzle. They send an NDE person up to do a dye penetrant test and it was good (no cracks) so we proceeded to X-ray the weld which was also good. They said that it is ok to weld SS to carbon steel with carbon steel as long as it doesn't crack and you aren't worried about chrome dilution (which is why we would have use 309L) on the SS part. In this case dilution of the chrome in the SS nipple was not an issue since it was supposed to be carbon steel anyway.
I learned something new that day. I have since then welded a lot of stainless at home using E-7018 rod with good results.